细说Cookie

Cookie虽然是个很简单的东西，但它又是WEB开发中一个很重要的客户端数据来源，而且它可以实现扩展性很好的会话状态，所以我认为每个WEB开发人员都有必要对它有个清晰的认识。本文将对Cookie这个话题做一个全面的描述，也算是我对Cookie的认识总结。
Cookie 概述

Cookie是什么？ Cookie 是一小段文本信息，伴随着用户请求和页面在 Web 服务器和浏览器之间传递。Cookie 包含每次用户访问站点时 Web 应用程序都可以读取的信息。
为什么需要Cookie？ 因为HTTP协议是无状态的，对于一个浏览器发出的多次请求，WEB服务器无法区分是不是来源于同一个浏览器。所以，需要额外的数据用于维护会话。Cookie 正是这样的一段随HTTP请求一起被传递的额外数据。
Cookie能做什么？ Cookie只是一段文本，所以它只能保存字符串。而且浏览器对它有大小限制以及它会随着每次请求被发送到服务器，所以应该保证它不要太大。Cookie的内容也是明文保存的，有些浏览器提供界面修改，所以，不适合保存重要的或者涉及隐私的内容。
Cookie 的限制。 大多数浏览器支持最大为 4096 字节的 Cookie。由于这限制了 Cookie 的大小，最好用 Cookie 来存储少量数据，或者存储用户 ID 之类的标识符。用户 ID 随后便可用于标识用户，以及从数据库或其他数据源中读取用户信息。浏览器还限制站点可以在用户计算机上存储的 Cookie 的数量。大多数浏览器只允许每个站点存储 20 个 Cookie；如果试图存储更多 Cookie，则最旧的 Cookie 便会被丢弃。有些浏览器还会对它们将接受的来自所有站点的 Cookie 总数作出绝对限制，通常为 300 个。
通过前面的内容，我们了解到Cookie是用于维持服务端会话状态的，通常由服务端写入，在后续请求中，供服务端读取。下面本文将按这个过程看看Cookie是如何从服务端写入，最后如何传到服务端以及如何读取的。
Cookie的写、读过程

在Asp.net中，读写Cookie是通过使用HttpCookie类来完成的，它的定义如下：

1. public sealed class HttpCookie
2. {
3.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
4. </authentication><forms name="UserStatus"></forms>
5. </authentication>// 获取或设置将此 Cookie 与其关联的域。默认值为当前域。
6.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
7. </authentication><forms name="UserStatus"></forms>
8. </authentication>public string Domain { get; set; }
9.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
10. </authentication><forms name="UserStatus"></forms>
11. </authentication>// 获取或设置此 Cookie 的过期日期和时间（在客户端）。
12.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
13. </authentication><forms name="UserStatus"></forms>
14. </authentication>public DateTime Expires { get; set; }
15.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
16. </authentication><forms name="UserStatus"></forms>
17. </authentication>// 获取一个值，通过该值指示 Cookie 是否具有子键。
18.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
19. </authentication><forms name="UserStatus"></forms>
20. </authentication>public bool HasKeys { get; }
21.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
22. </authentication><forms name="UserStatus"></forms>
23. </authentication>// 获取或设置一个值，该值指定 Cookie 是否可通过客户端脚本访问。
24.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
25. </authentication><forms name="UserStatus"></forms>
26. </authentication>// 如果 Cookie 具有 HttpOnly 属性且不能通过客户端脚本访问，则为 true；否则为 false。默认为 false。
27.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
28. </authentication><forms name="UserStatus"></forms>
29. </authentication>public bool HttpOnly { get; set; }
30.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
31. </authentication><forms name="UserStatus"></forms>
32. </authentication>// 获取或设置 Cookie 的名称。
33.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
34. </authentication><forms name="UserStatus"></forms>
35. </authentication>public string Name { get; set; }
36.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
37. </authentication><forms name="UserStatus"></forms>
38. </authentication>// 获取或设置要与当前 Cookie 一起传输的虚拟路径。默认值为当前请求的路径。
39.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
40. </authentication><forms name="UserStatus"></forms>
41. </authentication>public string Path { get; set; }
42.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
43. </authentication><forms name="UserStatus"></forms>
44. </authentication>// 获取或设置一个值，该值指示是否使用安全套接字层 (SSL)（即仅通过 HTTPS）传输 Cookie。
45.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
46. </authentication><forms name="UserStatus"></forms>
47. </authentication>public bool Secure { get; set; }
48.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
49. </authentication><forms name="UserStatus"></forms>
50. </authentication>// 获取或设置单个 Cookie 值。默认值为空引用。
51.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
52. </authentication><forms name="UserStatus"></forms>
53. </authentication>public string Value { get; set; }
54.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
55. </authentication><forms name="UserStatus"></forms>
56. </authentication>// 获取单个 Cookie 对象所包含的键值对的集合。
57.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
58. </authentication><forms name="UserStatus"></forms>
59. </authentication>public NameValueCollection Values { get; }
60.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
61. </authentication><forms name="UserStatus"></forms>
62. </authentication>// 获取 System.Web.HttpCookie.Values 属性的快捷方式。
63.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
64. </authentication><forms name="UserStatus"></forms>
65. </authentication>public string this[string key] { get; set; }
66. }

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Cookie写入浏览器的过程：我们可以使用如下代码在Asp.net项目中写一个Cookie 并发送到客户端的浏览器（为了简单我没有设置其它属性）。

1. HttpCookie cookie = new HttpCookie("MyCookieName", "string value");
2. Response.Cookies.Add(cookie);

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我想很多人都写过类似的代码，但是，大家有没有想过：Cookie最后是如何发送到客户端的呢？我们打开Fiddler来看一下吧。

从上图，您应该能发现，我们在服务端写的Cookie，最后其实是通过HTTP的响应头这种途径发送到客户端的。每一个写入动作，都会产生一个【Set-Cookie】的响应头。
浏览器正是在每次获取请求的响应后，检查这些头来接收Cookie的。
Asp.net获取Cookie的过程：我们可以使用如下代码在Asp.net项目中读取一个Cookie

1. HttpCookie cookie = Request.Cookies["MyCookieName"];
2. if( cookie != null )
3.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
4. </authentication><forms name="UserStatus"></forms>
5. </authentication>labCookie1.Text = cookie.Value;
6. else
7.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
8. </authentication><forms name="UserStatus"></forms>
9. </authentication>labCookie1.Text = "未定义";

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代码同样也很简单，还是类似的问题：大家有没有想过，Cookie是如何传到服务端的呢？我们还是继续使用Fiddler来寻找答案吧。

从图片中，我们可以发现，Cookie是放在请求头中，发送到服务端的。如果你一直刷新页面，就能发现，每次HTTP请求，Cookie都会被发送。当然了，浏览器也不是发送它所接收到的所有Cookie，它会检查当前要请求的域名以及目录，只要这二项目与Cookie对应的Domain和Path匹配，才会发送。对于Domain则是按照尾部匹配的原则进行的。
所以，我在访问 www.cnblogs.com 时，浏览器并不会将我在浏览 www.163.com 所接收到的 Cookie 发出去。
删除Cookie：其实就是在写Cookie时，设置Expires为一个【早于现在时间的时间】。也就是：设置此Cookie已经过期，浏览器接收到这个Cookie时，便会删除它们。

1. HttpCookie cookie = new HttpCookie("MyCookieName", null);
2. cookie.Expires = new DateTime(1900, 1, 1);
3. Response.Cookies.Add(cookie);

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使用Cookie保存复杂对象

前面的示例代码大致演示了Cookie的读写操作。不过，我们平时可能希望将更复杂的【自定义类型】通过Cookie来保存，那么又该如何操作呢？对于这个问题，我们定义一个类型来看看如何处理。

1. public class DisplaySettings
2. {
3.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
4. </authentication><forms name="UserStatus"></forms>
5. </authentication>public int Style;
7.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
8. </authentication><forms name="UserStatus"></forms>
9. </authentication>public int Size;
10.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
11. </authentication><forms name="UserStatus"></forms>
12. </authentication>
13.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
14. </authentication><forms name="UserStatus"></forms>
15. </authentication>public override string ToString()
16.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
17. </authentication><forms name="UserStatus"></forms>
18. </authentication>{
19.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
20. </authentication><forms name="UserStatus"></forms>
21. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
22. </authentication><forms name="UserStatus"></forms>
23. </authentication>return string.Format("Style = {0}, Size = {1}", this.Style, this.Size);
24.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
25. </authentication><forms name="UserStatus"></forms>
26. </authentication>}    <forms name="MyCookieName" cookieless="UseCookies"></forms>
27. </authentication><forms name="UserStatus"></forms>
28. </authentication>
29. }

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上面的代码，我定义一个类型，用于保存用户在浏览页面时的显示设置。接下来，我将介绍二种方法在Cookie中保存并读取它们。
方法-1，经典做法。（注意前面给出的HttpCookie定义代码中的最后二个成员）

1. private void WriteCookie_2a()
2. {
3.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
4. </authentication><forms name="UserStatus"></forms>
5. </authentication>DisplaySettings setting = new DisplaySettings { Style = 1, Size = 24 };
7.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
8. </authentication><forms name="UserStatus"></forms>
9. </authentication>HttpCookie cookie = new HttpCookie("DisplaySettings1");
10.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
11. </authentication><forms name="UserStatus"></forms>
12. </authentication>cookie["Style"] = setting.Style.ToString();
13.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
14. </authentication><forms name="UserStatus"></forms>
15. </authentication>cookie["Size"] = setting.Size.ToString();
17.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
18. </authentication><forms name="UserStatus"></forms>
19. </authentication>Response.Cookies.Add(cookie);
20. }
22. private void ReadCookie_2a()
23. {
24.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
25. </authentication><forms name="UserStatus"></forms>
26. </authentication>HttpCookie cookie = Request.Cookies["DisplaySettings1"];
27.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
28. </authentication><forms name="UserStatus"></forms>
29. </authentication>if( cookie == null )
30.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
31. </authentication><forms name="UserStatus"></forms>
32. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
33. </authentication><forms name="UserStatus"></forms>
34. </authentication>labDisplaySettings1.Text = "未定义";
35.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
36. </authentication><forms name="UserStatus"></forms>
37. </authentication>else {
38.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
39. </authentication><forms name="UserStatus"></forms>
40. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
41. </authentication><forms name="UserStatus"></forms>
42. </authentication>DisplaySettings setting = new DisplaySettings();
43.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
44. </authentication><forms name="UserStatus"></forms>
45. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
46. </authentication><forms name="UserStatus"></forms>
47. </authentication>setting.Style = cookie["Style"].TryToInt();
48.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
49. </authentication><forms name="UserStatus"></forms>
50. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
51. </authentication><forms name="UserStatus"></forms>
52. </authentication>setting.Size = cookie["Size"].TryToInt();
53.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
54. </authentication><forms name="UserStatus"></forms>
55. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
56. </authentication><forms name="UserStatus"></forms>
57. </authentication>labDisplaySettings1.Text = setting.ToString();
58.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
59. </authentication><forms name="UserStatus"></forms>
60. </authentication>}
61. }

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方法-2，将对象JSON序列化为字符串。

1. private void WriteCookie_2b()
2. {
3.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
4. </authentication><forms name="UserStatus"></forms>
5. </authentication>DisplaySettings setting = new DisplaySettings { Style = 2, Size = 48 };
7.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
8. </authentication><forms name="UserStatus"></forms>
9. </authentication>HttpCookie cookie = new HttpCookie("DisplaySettings2", setting.ToJson());
10.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
11. </authentication><forms name="UserStatus"></forms>
12. </authentication>Response.Cookies.Add(cookie);
13. }
15. private void ReadCookie_2b()
16. {
17.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
18. </authentication><forms name="UserStatus"></forms>
19. </authentication>HttpCookie cookie = Request.Cookies["DisplaySettings2"];
20.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
21. </authentication><forms name="UserStatus"></forms>
22. </authentication>if( cookie == null )
23.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
24. </authentication><forms name="UserStatus"></forms>
25. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
26. </authentication><forms name="UserStatus"></forms>
27. </authentication>labDisplaySettings2.Text = "未定义";
28.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
29. </authentication><forms name="UserStatus"></forms>
30. </authentication>else {
31.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
32. </authentication><forms name="UserStatus"></forms>
33. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
34. </authentication><forms name="UserStatus"></forms>
35. </authentication>DisplaySettings setting = cookie.Value.FromJson<DisplaySettings>();
36.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
37. </authentication><forms name="UserStatus"></forms>
38. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
39. </authentication><forms name="UserStatus"></forms>
40. </authentication>labDisplaySettings2.Text = setting.ToString();
41.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
42. </authentication><forms name="UserStatus"></forms>
43. </authentication>}
44. }

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这段代码使用了我定义的二个扩展方法。

1. /// <summary>
2. /// 将一个对象序列化成 JSON 格式字符串
3. /// </summary>
4. /// <param name="obj"></param>
5. /// <returns></returns>
6. public static string ToJson(this object obj)
7. {
8.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
9. </authentication><forms name="UserStatus"></forms>
10. </authentication>if( obj == null )
11.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
12. </authentication><forms name="UserStatus"></forms>
13. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
14. </authentication><forms name="UserStatus"></forms>
15. </authentication>return string.Empty;
17.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
18. </authentication><forms name="UserStatus"></forms>
19. </authentication>JavaScriptSerializer jss = new JavaScriptSerializer();
20.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
21. </authentication><forms name="UserStatus"></forms>
22. </authentication>return jss.Serialize(obj);
23. }
25. /// <summary>
26. /// 从JSON字符串中反序列化对象
27. /// </summary>
28. /// <typeparam name="T"></typeparam>
29. /// <param name="cookie"></param>
30. /// <returns></returns>
31. public static T FromJson<T>(this string cookie)
32. {
33.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
34. </authentication><forms name="UserStatus"></forms>
35. </authentication>if( string.IsNullOrEmpty(cookie) )
36.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
37. </authentication><forms name="UserStatus"></forms>
38. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
39. </authentication><forms name="UserStatus"></forms>
40. </authentication>return default(T);
42.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
43. </authentication><forms name="UserStatus"></forms>
44. </authentication>JavaScriptSerializer jss = new JavaScriptSerializer();
45.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
46. </authentication><forms name="UserStatus"></forms>
47. </authentication>return jss.Deserialize<T>(cookie);
48. }

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对于这二种方法，我个人更喜欢后者，因为它具有更好扩展性：如果类型增加了成员，不需要修改读写Cookie的代码。
不过，这种方式产生的有些字符，比如【双引号】，极少数浏览器(Opera)不支持，所以需要做UrlEncode或者Base64编码处理。
同理，对于第一种方法，遇到Value有【双引号】时，我们同样需要做UrlEncode或者Base64编码处理。
Js中读写Cookie

Cookie并非只能在服务端读写，在客户端的浏览器中也可以实现对它的读写访问。而且在JS中创建的Cookie对于服务端仍然有效（可见），接下来我们来看看在JS中如何写入Cookie，演示代码将创建一个按钮，并在点击按钮后写入Cookie

1. [/code]在JS中写Cookie很简单，只要给document.cookie赋值一个Cookie字符串即可，至于格式，可以参考前面用Fiddle看到的结果。
2. 再来看一下如何使用JS读取Cookie吧。请参考如下代码：
3. [code]

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仍然是访问document.cookie，不过，这次我们得到却是全部的Cookie值，每个Key/Value项用分号分开，中间则用等号分开。 所以，如果您想在JS中读取Cookie，一定要按照这个规则来拆分并解析您要读取的Cookie项。鉴于这样的操作有些繁琐，我们可以jquery.cookie.js插件来轻松完成这个功能，有兴趣的朋友也可以看一下它是如何处理的。这个插件的代码比较少，这里就直接贴出，

1. /**
2. * Create a cookie with the given name and value and other optional parameters.
3. *
4. * @example $.cookie('the_cookie', 'the_value');
5. * @desc Set the value of a cookie.
6. * @example $.cookie('the_cookie', 'the_value', {expires: 7, path: '/', domain: 'jquery.com', secure: true});
7. * @desc Create a cookie with all available options.
8. * @example $.cookie('the_cookie', 'the_value');
9. * @desc Create a session cookie.
10. * @example $.cookie('the_cookie', null);
11. * @desc Delete a cookie by passing null as value.
12. *
13. * @param String name The name of the cookie.
14. * @param String value The value of the cookie.
15. * @param Object options An object literal containing key/value pairs to provide optional cookie attributes.
16. * @option Number|Date expires Either an integer specifying the expiration date from now on in days or a Date object.
17. *    <forms name="MyCookieName" cookieless="UseCookies"></forms>
18. </authentication><forms name="UserStatus"></forms>
19. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
20. </authentication><forms name="UserStatus"></forms>
21. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
22. </authentication><forms name="UserStatus"></forms>
23. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
24. </authentication><forms name="UserStatus"></forms>
25. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
26. </authentication><forms name="UserStatus"></forms>
27. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
28. </authentication><forms name="UserStatus"></forms>
29. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
30. </authentication><forms name="UserStatus"></forms>
31. </authentication> If a negative value is specified (e.g. a date in the past), the cookie will be deleted.
32. *    <forms name="MyCookieName" cookieless="UseCookies"></forms>
33. </authentication><forms name="UserStatus"></forms>
34. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
35. </authentication><forms name="UserStatus"></forms>
36. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
37. </authentication><forms name="UserStatus"></forms>
38. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
39. </authentication><forms name="UserStatus"></forms>
40. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
41. </authentication><forms name="UserStatus"></forms>
42. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
43. </authentication><forms name="UserStatus"></forms>
44. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
45. </authentication><forms name="UserStatus"></forms>
46. </authentication> If set to null or omitted, the cookie will be a session cookie and will not be retained
47. *    <forms name="MyCookieName" cookieless="UseCookies"></forms>
48. </authentication><forms name="UserStatus"></forms>
49. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
50. </authentication><forms name="UserStatus"></forms>
51. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
52. </authentication><forms name="UserStatus"></forms>
53. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
54. </authentication><forms name="UserStatus"></forms>
55. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
56. </authentication><forms name="UserStatus"></forms>
57. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
58. </authentication><forms name="UserStatus"></forms>
59. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
60. </authentication><forms name="UserStatus"></forms>
61. </authentication> when the the browser exits.
62. * @option String path The value of the path atribute of the cookie (default: path of page that created the cookie).
63. * @option String domain The value of the domain attribute of the cookie (default: domain of page that created the cookie).
64. * @option Boolean secure If true, the secure attribute of the cookie will be set and the cookie transmission will
65. *    <forms name="MyCookieName" cookieless="UseCookies"></forms>
66. </authentication><forms name="UserStatus"></forms>
67. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
68. </authentication><forms name="UserStatus"></forms>
69. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
70. </authentication><forms name="UserStatus"></forms>
71. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
72. </authentication><forms name="UserStatus"></forms>
73. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
74. </authentication><forms name="UserStatus"></forms>
75. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
76. </authentication><forms name="UserStatus"></forms>
77. </authentication>require a secure protocol (like HTTPS).
78. * @type undefined
79. *
80. * @name $.cookie
81. * @cat Plugins/Cookie
82. * @author Klaus Hartl/klaus.hartl@stilbuero.de
83. */
85. /**
86. * Get the value of a cookie with the given name.
87. *
88. * @example $.cookie('the_cookie');
89. * @desc Get the value of a cookie.
90. *
91. * @param String name The name of the cookie.
92. * @return The value of the cookie.
93. * @type String
94. *
95. * @name $.cookie
96. * @cat Plugins/Cookie
97. * @author Klaus Hartl/klaus.hartl@stilbuero.de
98. */
99. jQuery.cookie = function(name, value, options) {
100.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
101. </authentication><forms name="UserStatus"></forms>
102. </authentication>if (typeof value != 'undefined') { // name and value given, set cookie
103.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
104. </authentication><forms name="UserStatus"></forms>
105. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
106. </authentication><forms name="UserStatus"></forms>
107. </authentication>options = options || {};
108.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
109. </authentication><forms name="UserStatus"></forms>
110. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
111. </authentication><forms name="UserStatus"></forms>
112. </authentication>if (value === null) {
113.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
114. </authentication><forms name="UserStatus"></forms>
115. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
116. </authentication><forms name="UserStatus"></forms>
117. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
118. </authentication><forms name="UserStatus"></forms>
119. </authentication>value = '';
120.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
121. </authentication><forms name="UserStatus"></forms>
122. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
123. </authentication><forms name="UserStatus"></forms>
124. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
125. </authentication><forms name="UserStatus"></forms>
126. </authentication>options.expires = -1;
127.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
128. </authentication><forms name="UserStatus"></forms>
129. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
130. </authentication><forms name="UserStatus"></forms>
131. </authentication>}
132.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
133. </authentication><forms name="UserStatus"></forms>
134. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
135. </authentication><forms name="UserStatus"></forms>
136. </authentication>var expires = '';
137.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
138. </authentication><forms name="UserStatus"></forms>
139. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
140. </authentication><forms name="UserStatus"></forms>
141. </authentication>if (options.expires && (typeof options.expires == 'number' || options.expires.toUTCString)) {
142.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
143. </authentication><forms name="UserStatus"></forms>
144. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
145. </authentication><forms name="UserStatus"></forms>
146. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
147. </authentication><forms name="UserStatus"></forms>
148. </authentication>var date;
149.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
150. </authentication><forms name="UserStatus"></forms>
151. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
152. </authentication><forms name="UserStatus"></forms>
153. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
154. </authentication><forms name="UserStatus"></forms>
155. </authentication>if (typeof options.expires == 'number') {
156.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
157. </authentication><forms name="UserStatus"></forms>
158. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
159. </authentication><forms name="UserStatus"></forms>
160. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
161. </authentication><forms name="UserStatus"></forms>
162. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
163. </authentication><forms name="UserStatus"></forms>
164. </authentication>date = new Date();
165.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
166. </authentication><forms name="UserStatus"></forms>
167. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
168. </authentication><forms name="UserStatus"></forms>
169. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
170. </authentication><forms name="UserStatus"></forms>
171. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
172. </authentication><forms name="UserStatus"></forms>
173. </authentication>date.setTime(date.getTime() + (options.expires * 24 * 60 * 60 * 1000));
174.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
175. </authentication><forms name="UserStatus"></forms>
176. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
177. </authentication><forms name="UserStatus"></forms>
178. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
179. </authentication><forms name="UserStatus"></forms>
180. </authentication>} else {
181.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
182. </authentication><forms name="UserStatus"></forms>
183. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
184. </authentication><forms name="UserStatus"></forms>
185. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
186. </authentication><forms name="UserStatus"></forms>
187. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
188. </authentication><forms name="UserStatus"></forms>
189. </authentication>date = options.expires;
190.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
191. </authentication><forms name="UserStatus"></forms>
192. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
193. </authentication><forms name="UserStatus"></forms>
194. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
195. </authentication><forms name="UserStatus"></forms>
196. </authentication>}
197.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
198. </authentication><forms name="UserStatus"></forms>
199. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
200. </authentication><forms name="UserStatus"></forms>
201. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
202. </authentication><forms name="UserStatus"></forms>
203. </authentication>expires = '; expires=' + date.toUTCString(); // use expires attribute, max-age is not supported by IE
204.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
205. </authentication><forms name="UserStatus"></forms>
206. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
207. </authentication><forms name="UserStatus"></forms>
208. </authentication>}
209.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
210. </authentication><forms name="UserStatus"></forms>
211. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
212. </authentication><forms name="UserStatus"></forms>
213. </authentication>var path = options.path ? '; path=' + options.path : '';
214.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
215. </authentication><forms name="UserStatus"></forms>
216. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
217. </authentication><forms name="UserStatus"></forms>
218. </authentication>var domain = options.domain ? '; domain=' + options.domain : '';
219.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
220. </authentication><forms name="UserStatus"></forms>
221. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
222. </authentication><forms name="UserStatus"></forms>
223. </authentication>var secure = options.secure ? '; secure' : '';
224.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
225. </authentication><forms name="UserStatus"></forms>
226. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
227. </authentication><forms name="UserStatus"></forms>
228. </authentication>document.cookie = [name, '=', encodeURIComponent(value), expires, path, domain, secure].join('');
229.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
230. </authentication><forms name="UserStatus"></forms>
231. </authentication>} else { // only name given, get cookie
232.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
233. </authentication><forms name="UserStatus"></forms>
234. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
235. </authentication><forms name="UserStatus"></forms>
236. </authentication>var cookieValue = null;
237.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
238. </authentication><forms name="UserStatus"></forms>
239. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
240. </authentication><forms name="UserStatus"></forms>
241. </authentication>if (document.cookie && document.cookie != '') {
242.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
243. </authentication><forms name="UserStatus"></forms>
244. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
245. </authentication><forms name="UserStatus"></forms>
246. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
247. </authentication><forms name="UserStatus"></forms>
248. </authentication>var cookies = document.cookie.split(';');
249.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
250. </authentication><forms name="UserStatus"></forms>
251. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
252. </authentication><forms name="UserStatus"></forms>
253. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
254. </authentication><forms name="UserStatus"></forms>
255. </authentication>for (var i = 0; i < cookies.length; i++) {
256.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
257. </authentication><forms name="UserStatus"></forms>
258. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
259. </authentication><forms name="UserStatus"></forms>
260. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
261. </authentication><forms name="UserStatus"></forms>
262. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
263. </authentication><forms name="UserStatus"></forms>
264. </authentication>var cookie = jQuery.trim(cookies[i]);
265.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
266. </authentication><forms name="UserStatus"></forms>
267. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
268. </authentication><forms name="UserStatus"></forms>
269. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
270. </authentication><forms name="UserStatus"></forms>
271. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
272. </authentication><forms name="UserStatus"></forms>
273. </authentication>// Does this cookie string begin with the name we want?
274.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
275. </authentication><forms name="UserStatus"></forms>
276. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
277. </authentication><forms name="UserStatus"></forms>
278. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
279. </authentication><forms name="UserStatus"></forms>
280. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
281. </authentication><forms name="UserStatus"></forms>
282. </authentication>if (cookie.substring(0, name.length + 1) == (name + '=')) {
283.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
284. </authentication><forms name="UserStatus"></forms>
285. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
286. </authentication><forms name="UserStatus"></forms>
287. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
288. </authentication><forms name="UserStatus"></forms>
289. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
290. </authentication><forms name="UserStatus"></forms>
291. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
292. </authentication><forms name="UserStatus"></forms>
293. </authentication>cookieValue = decodeURIComponent(cookie.substring(name.length + 1));
294.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
295. </authentication><forms name="UserStatus"></forms>
296. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
297. </authentication><forms name="UserStatus"></forms>
298. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
299. </authentication><forms name="UserStatus"></forms>
300. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
301. </authentication><forms name="UserStatus"></forms>
302. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
303. </authentication><forms name="UserStatus"></forms>
304. </authentication>break;
305.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
306. </authentication><forms name="UserStatus"></forms>
307. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
308. </authentication><forms name="UserStatus"></forms>
309. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
310. </authentication><forms name="UserStatus"></forms>
311. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
312. </authentication><forms name="UserStatus"></forms>
313. </authentication>}
314.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
315. </authentication><forms name="UserStatus"></forms>
316. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
317. </authentication><forms name="UserStatus"></forms>
318. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
319. </authentication><forms name="UserStatus"></forms>
320. </authentication>}
321.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
322. </authentication><forms name="UserStatus"></forms>
323. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
324. </authentication><forms name="UserStatus"></forms>
325. </authentication>}
326.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
327. </authentication><forms name="UserStatus"></forms>
328. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
329. </authentication><forms name="UserStatus"></forms>
330. </authentication>return cookieValue;
331.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
332. </authentication><forms name="UserStatus"></forms>
333. </authentication>}
334. };

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注意哦：前面我们看到了HttpCookie有个HttpOnly属性，如果它为true，那么JS是读不到那个Cookie的，也就是说：我们如果在服务端生成的Cookie不希望在JS中能被访问，可以在写Cookie时，设置这个属性。不过，通过一些工具，还是可以看到它们。
接下来，我们再来看看Asp.net中Cookie有哪些应用。
Cookie在Session中的应用

在Asp.net中，HttpContext, Page对象都有个Session的对象，我们可以使用它来方便地在服务端保存一些与会话相关的信息。
前面我们也提到过，HTTP协议是无状态的，对于一个浏览器发出的多次请求，WEB服务器无法区分 是不是来源于同一个浏览器。所以，为了实现会话，服务端需要一个会话标识ID能保存到浏览器，让它在后续的请求时都带上这个会话标识ID，以便让服务端知道某个请求属于哪个会话，这样便可以维护与会话相关的状态数据。由于Cookie对于用户来说，是个不可见的东西，而且每次请求都会传递到服务端，所以它就是很理想的会话标识ID的保存容器。在Asp.net中，默认也就是使用Cookie来保存这个ID的。注意：虽然Asp.net 2.0也支持无Cookie的会话，但那种方式要修改URL，也有它的缺点，因此这种方法并没有广泛的使用。本文将不对这个话题做过多的分析，就此略过无Cookie会话这种方式。
我们来看看Session是如何使用Cookie来保存会话标识ID的，在默认的Asp.net配置中，Web.config有着如下定义：

1. [/code]如果我们执行以下操作：
2. [code]Session["Key1"] = DateTime.Now;

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此时，我们可以使用一些浏览器提供的工具来查看一下现在的Cookie情况。

从图片上看，这个Cookie的名字就是我们在配置文件中指出的名称，我们可以修改一下配置文件：

1. [/code]再来执行上面的写Session的操作，然后看Cookie
2. [align=center] [/align]
3. 我们可以看到：SK的Cookie出现了。说明：在截图时我把名称为"ASP.NET_SessionId"的Cookie删除了。
4. 通过上面示例，我们可以得到结论，Session的实现是与Cookie有关的，服务端需要将会话标识ID保存到Cookie中。
5. 这里再一次申明，除非你使用无Cookie的会话模式，否则Session是需要Cookie的支持。反过来，Cookie并不需要Session的支持。
6. [size=6]Cookie在身份验证中的应用[/size]
8. 我想很多人都在Asp.net的开发中使用过Form身份认证。对于一个用户请求，我们可以在服务端很方便地判断它是不是代表一个已登录用户。
9. [code]this.labStatus.Text = (Request.IsAuthenticated ? "已登录" : "未登录");

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那么，您有没有好奇过：Asp.net是如何识别一个请求是不是一个已登录用户发起的呢？说到这里，我们就要从用户登录说起了。为了实现登录及Form认证方式，我们需要如下配置：

1.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
2. </authentication><forms name="UserStatus"></forms>
3. </authentication>

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接下来，我们需要实现用户登录逻辑。具体实现方式有很多，不过，最终的调用都是差不多的，如下代码所示：

1. private void SetLogin(){    <forms name="MyCookieName" cookieless="UseCookies"></forms>
2. </authentication><forms name="UserStatus"></forms>
3. </authentication>System.Web.Security.FormsAuthentication.SetAuthCookie("fish", false);}

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只要执行了以上代码，我们就可以看到，前面的判断【Request.IsAuthenticated】返回true，最终会显示"已登录"。为了探寻这个秘密，我们还是来看一下当前页面的Cookie情况。

果然，多出来一个Cookie，名称与我在配置文件中指定的名称相同。我们再来看看如果注销当前登录会是什么样子的：

1. private void SetLogout(){    <forms name="MyCookieName" cookieless="UseCookies"></forms>
2. </authentication><forms name="UserStatus"></forms>
3. </authentication>System.Web.Security.FormsAuthentication.SignOut();}

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看到了吗，名为"UserStatus"的Cookie不见了。此时如果你再去观察【Request.IsAuthenticated】，可以发现它此时返回 false。或者，您也可以再试一次，登录后，直接删除名为"UserStatus"的Cookie，也能发现登录状态将显示"未登录"。或许，您还是有点不清楚前面我调用【System.Web.Security.FormsAuthentication.SetAuthCookie("fish", false);】后，Asp.net做了些什么，回答这个问题其实很简单：自己用Reflector.exe去看一下Asp.net的实现吧。
这里为了更让您能信服登录与Cookie有关，我将直接创建一个Cookie看一下Asp.net能不能认可我创建的Cookie，并认为登录有效。请看代码：

1. private void SetLogin(){    <forms name="MyCookieName" cookieless="UseCookies"></forms>
2. </authentication><forms name="UserStatus"></forms>
3. </authentication>//System.Web.Security.FormsAuthentication.SetAuthCookie("fish", false);    <forms name="MyCookieName" cookieless="UseCookies"></forms>
4. </authentication><forms name="UserStatus"></forms>
5. </authentication>// 下面的代码和上面的代码在作用上是等效的。    <forms name="MyCookieName" cookieless="UseCookies"></forms>
6. </authentication><forms name="UserStatus"></forms>
7. </authentication>FormsAuthenticationTicket ticket = new FormsAuthenticationTicket(    <forms name="MyCookieName" cookieless="UseCookies"></forms>
8. </authentication><forms name="UserStatus"></forms>
9. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
10. </authentication><forms name="UserStatus"></forms>
11. </authentication>2, "fish", DateTime.Now, DateTime.Now.AddDays(30d), false, string.Empty);    <forms name="MyCookieName" cookieless="UseCookies"></forms>
12. </authentication><forms name="UserStatus"></forms>
13. </authentication>string str = FormsAuthentication.Encrypt(ticket);    <forms name="MyCookieName" cookieless="UseCookies"></forms>
14. </authentication><forms name="UserStatus"></forms>
15. </authentication>HttpCookie cookie = new HttpCookie(FormsAuthentication.FormsCookieName, str);    <forms name="MyCookieName" cookieless="UseCookies"></forms>
16. </authentication><forms name="UserStatus"></forms>
17. </authentication>Response.Cookies.Add(cookie);}

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如果执行这段代码，您将发现：【Request.IsAuthenticated】返回true，登录状态会显示"已登录"。
至此，我们可以得出一个结论：Form身份认证依赖Cookie，Asp.net就是每次检查我们在配置文件中指定的Cookie名称，并解密这个Cookie来判断当前请求用户的登录状态。
Cookie的安全状况

从以上图片，您应该能发现：浏览器能提供一些界面让用户清楚的观察我们在服务端写的Cookie，甚至有些浏览器还提供很方便的修改功能。如下图所示：

所以，我们在服务端写代码读取Cookie时，尤其是涉及类型转换、反序列化或者解密时，一定要注意这些操作都有可能会失败。而且上图也清楚的反映了一个事实：Cookie中的值都是“一目了然”的，任何人都能看到它们。所以，我们尽量不要直接在Cookie中保存一些重要的或者敏感的内容。如果我们确实需要使用Cookie保存一些重要的内容，但又不希望被他人看懂，我们可以使用一些加密的方法来保护这些内容。
1. 对于一些重要性不高的内容，我们可以使用Base64之类的简单处理方式来处理。
2. 对于重要性相对高一点的内容，我们可以利用.net提供的一些加密工具类，自己来设计加密方法来保护。不过，密码学与加密解密并不是很简单的算法，因此，自己设计的加密方式可能不会很安全。
3. 重要的内容，我们可以使用.net提供的FormsAuthenticationTicket,FormsAuthentication来加密。我认为这种方式还是比较安全的。毕竟前面我们也看过了，Asp.net的Form身份认证就是使用这种方式来加密用户登录的身份标识的，所以，如果这种方式不安全，也就意味着Asp.net的身份认证也不安全了。如果您使用这种方式来加密，那么请注意：它产生的加密后文本还是比较大的，前面我也提到过，每次请求时，浏览器都会带上与请求相匹配的所有Cookie，因此，这种Cookie会对传输性能产生一定的影响，所以，请小心使用，切记不可过多的使用。
这里要补充一下：去年曾经出现过【Padding Oracle Attack】这个话题，一些人甚至错误的认为是Asp.net加密方式不安全！如果您也是这样认为的，那么可以看一下这篇文章：浅谈这次ASP.NET的Padding Oracle Attack相关内容，以消除这个错误的认识。当然了，我们也可以从这个话题得到一些收获：解密失败时，不要给出过多的提示，就当没有这个Cookie存在。
如何在C#发请的请求中使用Cookie

前面我们一直在谈服务端与浏览器中使用Cookie，其实浏览器也是一个普通的应用程序，.net framework也提供一些类也能让我们直接发起HTTP请求，下面我们来看一下如何在C#发请的请求中使用Cookie ，其实也很简单，主要是使用了CookieContainer类，请看以下演示代码：

1. private static string SendHttpRequestGet(string url, Encoding encoding,    <forms name="MyCookieName" cookieless="UseCookies"></forms>
2. </authentication><forms name="UserStatus"></forms>
3. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
4. </authentication><forms name="UserStatus"></forms>
5. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
6. </authentication><forms name="UserStatus"></forms>
7. </authentication> CookieContainer cookieContainer)    <forms name="MyCookieName" cookieless="UseCookies"></forms>
8. </authentication><forms name="UserStatus"></forms>
9. </authentication>{    <forms name="MyCookieName" cookieless="UseCookies"></forms>
10. </authentication><forms name="UserStatus"></forms>
11. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
12. </authentication><forms name="UserStatus"></forms>
13. </authentication>if( string.IsNullOrEmpty(url) )    <forms name="MyCookieName" cookieless="UseCookies"></forms>
14. </authentication><forms name="UserStatus"></forms>
15. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
16. </authentication><forms name="UserStatus"></forms>
17. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
18. </authentication><forms name="UserStatus"></forms>
19. </authentication>throw new ArgumentNullException("url");    <forms name="MyCookieName" cookieless="UseCookies"></forms>
20. </authentication><forms name="UserStatus"></forms>
21. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
22. </authentication><forms name="UserStatus"></forms>
23. </authentication>if( encoding == null )    <forms name="MyCookieName" cookieless="UseCookies"></forms>
24. </authentication><forms name="UserStatus"></forms>
25. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
26. </authentication><forms name="UserStatus"></forms>
27. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
28. </authentication><forms name="UserStatus"></forms>
29. </authentication>throw new ArgumentNullException("encoding");    <forms name="MyCookieName" cookieless="UseCookies"></forms>
30. </authentication><forms name="UserStatus"></forms>
31. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
32. </authentication><forms name="UserStatus"></forms>
33. </authentication>HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);    <forms name="MyCookieName" cookieless="UseCookies"></forms>
34. </authentication><forms name="UserStatus"></forms>
35. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
36. </authentication><forms name="UserStatus"></forms>
37. </authentication>request.Method = "GET";    <forms name="MyCookieName" cookieless="UseCookies"></forms>
38. </authentication><forms name="UserStatus"></forms>
39. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
40. </authentication><forms name="UserStatus"></forms>
41. </authentication>request.CookieContainer = cookieContainer;    <forms name="MyCookieName" cookieless="UseCookies"></forms>
42. </authentication><forms name="UserStatus"></forms>
43. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
44. </authentication><forms name="UserStatus"></forms>
45. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
46. </authentication><forms name="UserStatus"></forms>
47. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
48. </authentication><forms name="UserStatus"></forms>
49. </authentication>using( WebResponse response = request.GetResponse() ) {    <forms name="MyCookieName" cookieless="UseCookies"></forms>
50. </authentication><forms name="UserStatus"></forms>
51. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
52. </authentication><forms name="UserStatus"></forms>
53. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
54. </authentication><forms name="UserStatus"></forms>
55. </authentication>using( StreamReader reader = new StreamReader(response.GetResponseStream(), encoding) ) {    <forms name="MyCookieName" cookieless="UseCookies"></forms>
56. </authentication><forms name="UserStatus"></forms>
57. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
58. </authentication><forms name="UserStatus"></forms>
59. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
60. </authentication><forms name="UserStatus"></forms>
61. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
62. </authentication><forms name="UserStatus"></forms>
63. </authentication>return reader.ReadToEnd();    <forms name="MyCookieName" cookieless="UseCookies"></forms>
64. </authentication><forms name="UserStatus"></forms>
65. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
66. </authentication><forms name="UserStatus"></forms>
67. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
68. </authentication><forms name="UserStatus"></forms>
69. </authentication>}    <forms name="MyCookieName" cookieless="UseCookies"></forms>
70. </authentication><forms name="UserStatus"></forms>
71. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
72. </authentication><forms name="UserStatus"></forms>
73. </authentication>}    <forms name="MyCookieName" cookieless="UseCookies"></forms>
74. </authentication><forms name="UserStatus"></forms>
75. </authentication>}    <forms name="MyCookieName" cookieless="UseCookies"></forms>
76. </authentication><forms name="UserStatus"></forms>
77. </authentication>private void SendHttpDEMO()    <forms name="MyCookieName" cookieless="UseCookies"></forms>
78. </authentication><forms name="UserStatus"></forms>
79. </authentication>{    <forms name="MyCookieName" cookieless="UseCookies"></forms>
80. </authentication><forms name="UserStatus"></forms>
81. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
82. </authentication><forms name="UserStatus"></forms>
83. </authentication>StringBuilder sb = new StringBuilder();    <forms name="MyCookieName" cookieless="UseCookies"></forms>
84. </authentication><forms name="UserStatus"></forms>
85. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
86. </authentication><forms name="UserStatus"></forms>
87. </authentication>CookieContainer cookieContainer = new CookieContainer();    <forms name="MyCookieName" cookieless="UseCookies"></forms>
88. </authentication><forms name="UserStatus"></forms>
89. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
90. </authentication><forms name="UserStatus"></forms>
91. </authentication>string url = "http://www.taobao.com";    <forms name="MyCookieName" cookieless="UseCookies"></forms>
92. </authentication><forms name="UserStatus"></forms>
93. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
94. </authentication><forms name="UserStatus"></forms>
95. </authentication>SendHttpRequestGet(url, Encoding.Default, cookieContainer);    <forms name="MyCookieName" cookieless="UseCookies"></forms>
96. </authentication><forms name="UserStatus"></forms>
97. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
98. </authentication><forms name="UserStatus"></forms>
99. </authentication>// 后面可以继续发起HTTP请求，此时将会包含上次从服务器写入的Cookie    <forms name="MyCookieName" cookieless="UseCookies"></forms>
100. </authentication><forms name="UserStatus"></forms>
101. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
102. </authentication><forms name="UserStatus"></forms>
103. </authentication>//SendHttpRequestGet("同域名下的其它URL", Encoding.Default, cookieContainer);    <forms name="MyCookieName" cookieless="UseCookies"></forms>
104. </authentication><forms name="UserStatus"></forms>
105. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
106. </authentication><forms name="UserStatus"></forms>
107. </authentication>// 至此，我们可以显示取得了哪些Cookie    <forms name="MyCookieName" cookieless="UseCookies"></forms>
108. </authentication><forms name="UserStatus"></forms>
109. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
110. </authentication><forms name="UserStatus"></forms>
111. </authentication>CookieCollection cookies = cookieContainer.GetCookies(new Uri(url));    <forms name="MyCookieName" cookieless="UseCookies"></forms>
112. </authentication><forms name="UserStatus"></forms>
113. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
114. </authentication><forms name="UserStatus"></forms>
115. </authentication>if( cookies != null ) {    <forms name="MyCookieName" cookieless="UseCookies"></forms>
116. </authentication><forms name="UserStatus"></forms>
117. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
118. </authentication><forms name="UserStatus"></forms>
119. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
120. </authentication><forms name="UserStatus"></forms>
121. </authentication>foreach( System.Net.Cookie cookie in cookies )    <forms name="MyCookieName" cookieless="UseCookies"></forms>
122. </authentication><forms name="UserStatus"></forms>
123. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
124. </authentication><forms name="UserStatus"></forms>
125. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
126. </authentication><forms name="UserStatus"></forms>
127. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
128. </authentication><forms name="UserStatus"></forms>
129. </authentication>sb.AppendLine(cookie.ToString());    <forms name="MyCookieName" cookieless="UseCookies"></forms>
130. </authentication><forms name="UserStatus"></forms>
131. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
132. </authentication><forms name="UserStatus"></forms>
133. </authentication>}    <forms name="MyCookieName" cookieless="UseCookies"></forms>
134. </authentication><forms name="UserStatus"></forms>
135. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
136. </authentication><forms name="UserStatus"></forms>
137. </authentication>txtCookies.Text = sb.ToString();    <forms name="MyCookieName" cookieless="UseCookies"></forms>
138. </authentication><forms name="UserStatus"></forms>
139. </authentication>}

复制代码

重构与使用总结

在前面的Asp.net示例代码中，我一直使用.net提供的HttpCookie类来操作Cookie，是为了展示用原始的方式来使用Cookie，这些代码有点重复，也有点繁琐，为此，我提供了几个简单的方法可以更容易的使用Cookie，也算是对Cookie使用的一个总结。

1. /// /// 用于方便使用Cookie的扩展工具类/// public static class CookieExtension{    <forms name="MyCookieName" cookieless="UseCookies"></forms>
2. </authentication><forms name="UserStatus"></forms>
3. </authentication>// 我们可以为一些使用频率高的类型写专门的【读取】方法    <forms name="MyCookieName" cookieless="UseCookies"></forms>
4. </authentication><forms name="UserStatus"></forms>
5. </authentication>///    <forms name="MyCookieName" cookieless="UseCookies"></forms>
6. </authentication><forms name="UserStatus"></forms>
7. </authentication> /// 从一个Cookie中读取字符串值。    <forms name="MyCookieName" cookieless="UseCookies"></forms>
8. </authentication><forms name="UserStatus"></forms>
9. </authentication>///    <forms name="MyCookieName" cookieless="UseCookies"></forms>
10. </authentication><forms name="UserStatus"></forms>
11. </authentication> ///    <forms name="MyCookieName" cookieless="UseCookies"></forms>
12. </authentication><forms name="UserStatus"></forms>
13. </authentication> ///    <forms name="MyCookieName" cookieless="UseCookies"></forms>
14. </authentication><forms name="UserStatus"></forms>
15. </authentication> public static string GetString(this HttpCookie cookie)    <forms name="MyCookieName" cookieless="UseCookies"></forms>
16. </authentication><forms name="UserStatus"></forms>
17. </authentication>{    <forms name="MyCookieName" cookieless="UseCookies"></forms>
18. </authentication><forms name="UserStatus"></forms>
19. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
20. </authentication><forms name="UserStatus"></forms>
21. </authentication>if( cookie == null )    <forms name="MyCookieName" cookieless="UseCookies"></forms>
22. </authentication><forms name="UserStatus"></forms>
23. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
24. </authentication><forms name="UserStatus"></forms>
25. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
26. </authentication><forms name="UserStatus"></forms>
27. </authentication>return null;    <forms name="MyCookieName" cookieless="UseCookies"></forms>
28. </authentication><forms name="UserStatus"></forms>
29. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
30. </authentication><forms name="UserStatus"></forms>
31. </authentication>return cookie.Value;    <forms name="MyCookieName" cookieless="UseCookies"></forms>
32. </authentication><forms name="UserStatus"></forms>
33. </authentication>}    <forms name="MyCookieName" cookieless="UseCookies"></forms>
34. </authentication><forms name="UserStatus"></forms>
35. </authentication>///    <forms name="MyCookieName" cookieless="UseCookies"></forms>
36. </authentication><forms name="UserStatus"></forms>
37. </authentication> /// 从一个Cookie中读取 Int 值。    <forms name="MyCookieName" cookieless="UseCookies"></forms>
38. </authentication><forms name="UserStatus"></forms>
39. </authentication>///    <forms name="MyCookieName" cookieless="UseCookies"></forms>
40. </authentication><forms name="UserStatus"></forms>
41. </authentication> ///    <forms name="MyCookieName" cookieless="UseCookies"></forms>
42. </authentication><forms name="UserStatus"></forms>
43. </authentication> ///    <forms name="MyCookieName" cookieless="UseCookies"></forms>
44. </authentication><forms name="UserStatus"></forms>
45. </authentication> ///    <forms name="MyCookieName" cookieless="UseCookies"></forms>
46. </authentication><forms name="UserStatus"></forms>
47. </authentication> public static int ToInt(this HttpCookie cookie, int defaultVal)    <forms name="MyCookieName" cookieless="UseCookies"></forms>
48. </authentication><forms name="UserStatus"></forms>
49. </authentication>{    <forms name="MyCookieName" cookieless="UseCookies"></forms>
50. </authentication><forms name="UserStatus"></forms>
51. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
52. </authentication><forms name="UserStatus"></forms>
53. </authentication>if( cookie == null )    <forms name="MyCookieName" cookieless="UseCookies"></forms>
54. </authentication><forms name="UserStatus"></forms>
55. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
56. </authentication><forms name="UserStatus"></forms>
57. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
58. </authentication><forms name="UserStatus"></forms>
59. </authentication>return defaultVal;    <forms name="MyCookieName" cookieless="UseCookies"></forms>
60. </authentication><forms name="UserStatus"></forms>
61. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
62. </authentication><forms name="UserStatus"></forms>
63. </authentication>return cookie.Value.TryToInt(defaultVal);    <forms name="MyCookieName" cookieless="UseCookies"></forms>
64. </authentication><forms name="UserStatus"></forms>
65. </authentication>}    <forms name="MyCookieName" cookieless="UseCookies"></forms>
66. </authentication><forms name="UserStatus"></forms>
67. </authentication>///    <forms name="MyCookieName" cookieless="UseCookies"></forms>
68. </authentication><forms name="UserStatus"></forms>
69. </authentication> /// 从一个Cookie中读取值并转成指定的类型    <forms name="MyCookieName" cookieless="UseCookies"></forms>
70. </authentication><forms name="UserStatus"></forms>
71. </authentication>///    <forms name="MyCookieName" cookieless="UseCookies"></forms>
72. </authentication><forms name="UserStatus"></forms>
73. </authentication> ///    <forms name="MyCookieName" cookieless="UseCookies"></forms>
74. </authentication><forms name="UserStatus"></forms>
75. </authentication> ///    <forms name="MyCookieName" cookieless="UseCookies"></forms>
76. </authentication><forms name="UserStatus"></forms>
77. </authentication> ///    <forms name="MyCookieName" cookieless="UseCookies"></forms>
78. </authentication><forms name="UserStatus"></forms>
79. </authentication> public static T ConverTo(this HttpCookie cookie)    <forms name="MyCookieName" cookieless="UseCookies"></forms>
80. </authentication><forms name="UserStatus"></forms>
81. </authentication>{    <forms name="MyCookieName" cookieless="UseCookies"></forms>
82. </authentication><forms name="UserStatus"></forms>
83. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
84. </authentication><forms name="UserStatus"></forms>
85. </authentication>if( cookie == null )    <forms name="MyCookieName" cookieless="UseCookies"></forms>
86. </authentication><forms name="UserStatus"></forms>
87. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
88. </authentication><forms name="UserStatus"></forms>
89. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
90. </authentication><forms name="UserStatus"></forms>
91. </authentication>return default(T);    <forms name="MyCookieName" cookieless="UseCookies"></forms>
92. </authentication><forms name="UserStatus"></forms>
93. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
94. </authentication><forms name="UserStatus"></forms>
95. </authentication>return (T)Convert.ChangeType(cookie.Value, typeof(T));    <forms name="MyCookieName" cookieless="UseCookies"></forms>
96. </authentication><forms name="UserStatus"></forms>
97. </authentication>}    <forms name="MyCookieName" cookieless="UseCookies"></forms>
98. </authentication><forms name="UserStatus"></forms>
99. </authentication>///    <forms name="MyCookieName" cookieless="UseCookies"></forms>
100. </authentication><forms name="UserStatus"></forms>
101. </authentication> /// 从一个Cookie中读取【JSON字符串】值并反序列化成一个对象，用于读取复杂对象    <forms name="MyCookieName" cookieless="UseCookies"></forms>
102. </authentication><forms name="UserStatus"></forms>
103. </authentication>///    <forms name="MyCookieName" cookieless="UseCookies"></forms>
104. </authentication><forms name="UserStatus"></forms>
105. </authentication> ///    <forms name="MyCookieName" cookieless="UseCookies"></forms>
106. </authentication><forms name="UserStatus"></forms>
107. </authentication> ///    <forms name="MyCookieName" cookieless="UseCookies"></forms>
108. </authentication><forms name="UserStatus"></forms>
109. </authentication> ///    <forms name="MyCookieName" cookieless="UseCookies"></forms>
110. </authentication><forms name="UserStatus"></forms>
111. </authentication> public static T FromJson(this HttpCookie cookie)    <forms name="MyCookieName" cookieless="UseCookies"></forms>
112. </authentication><forms name="UserStatus"></forms>
113. </authentication>{    <forms name="MyCookieName" cookieless="UseCookies"></forms>
114. </authentication><forms name="UserStatus"></forms>
115. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
116. </authentication><forms name="UserStatus"></forms>
117. </authentication>if( cookie == null )    <forms name="MyCookieName" cookieless="UseCookies"></forms>
118. </authentication><forms name="UserStatus"></forms>
119. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
120. </authentication><forms name="UserStatus"></forms>
121. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
122. </authentication><forms name="UserStatus"></forms>
123. </authentication>return default(T);    <forms name="MyCookieName" cookieless="UseCookies"></forms>
124. </authentication><forms name="UserStatus"></forms>
125. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
126. </authentication><forms name="UserStatus"></forms>
127. </authentication>return cookie.Value.FromJson();    <forms name="MyCookieName" cookieless="UseCookies"></forms>
128. </authentication><forms name="UserStatus"></forms>
129. </authentication>}    <forms name="MyCookieName" cookieless="UseCookies"></forms>
130. </authentication><forms name="UserStatus"></forms>
131. </authentication>///    <forms name="MyCookieName" cookieless="UseCookies"></forms>
132. </authentication><forms name="UserStatus"></forms>
133. </authentication> /// 将一个对象写入到Cookie    <forms name="MyCookieName" cookieless="UseCookies"></forms>
134. </authentication><forms name="UserStatus"></forms>
135. </authentication>///    <forms name="MyCookieName" cookieless="UseCookies"></forms>
136. </authentication><forms name="UserStatus"></forms>
137. </authentication> ///    <forms name="MyCookieName" cookieless="UseCookies"></forms>
138. </authentication><forms name="UserStatus"></forms>
139. </authentication> ///    <forms name="MyCookieName" cookieless="UseCookies"></forms>
140. </authentication><forms name="UserStatus"></forms>
141. </authentication> ///    <forms name="MyCookieName" cookieless="UseCookies"></forms>
142. </authentication><forms name="UserStatus"></forms>
143. </authentication> public static void WriteCookie(this object obj, string name, DateTime? expries)    <forms name="MyCookieName" cookieless="UseCookies"></forms>
144. </authentication><forms name="UserStatus"></forms>
145. </authentication>{    <forms name="MyCookieName" cookieless="UseCookies"></forms>
146. </authentication><forms name="UserStatus"></forms>
147. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
148. </authentication><forms name="UserStatus"></forms>
149. </authentication>if( obj == null )    <forms name="MyCookieName" cookieless="UseCookies"></forms>
150. </authentication><forms name="UserStatus"></forms>
151. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
152. </authentication><forms name="UserStatus"></forms>
153. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
154. </authentication><forms name="UserStatus"></forms>
155. </authentication>throw new ArgumentNullException("obj");    <forms name="MyCookieName" cookieless="UseCookies"></forms>
156. </authentication><forms name="UserStatus"></forms>
157. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
158. </authentication><forms name="UserStatus"></forms>
159. </authentication>if( string.IsNullOrEmpty(name) )    <forms name="MyCookieName" cookieless="UseCookies"></forms>
160. </authentication><forms name="UserStatus"></forms>
161. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
162. </authentication><forms name="UserStatus"></forms>
163. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
164. </authentication><forms name="UserStatus"></forms>
165. </authentication>throw new ArgumentNullException("name");    <forms name="MyCookieName" cookieless="UseCookies"></forms>
166. </authentication><forms name="UserStatus"></forms>
167. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
168. </authentication><forms name="UserStatus"></forms>
169. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
170. </authentication><forms name="UserStatus"></forms>
171. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
172. </authentication><forms name="UserStatus"></forms>
173. </authentication>HttpCookie cookie = new HttpCookie(name, obj.ToString());    <forms name="MyCookieName" cookieless="UseCookies"></forms>
174. </authentication><forms name="UserStatus"></forms>
175. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
176. </authentication><forms name="UserStatus"></forms>
177. </authentication>if( expries.HasValue )    <forms name="MyCookieName" cookieless="UseCookies"></forms>
178. </authentication><forms name="UserStatus"></forms>
179. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
180. </authentication><forms name="UserStatus"></forms>
181. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
182. </authentication><forms name="UserStatus"></forms>
183. </authentication>cookie.Expires = expries.Value;    <forms name="MyCookieName" cookieless="UseCookies"></forms>
184. </authentication><forms name="UserStatus"></forms>
185. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
186. </authentication><forms name="UserStatus"></forms>
187. </authentication>HttpContext.Current.Response.Cookies.Add(cookie);    <forms name="MyCookieName" cookieless="UseCookies"></forms>
188. </authentication><forms name="UserStatus"></forms>
189. </authentication>}    <forms name="MyCookieName" cookieless="UseCookies"></forms>
190. </authentication><forms name="UserStatus"></forms>
191. </authentication>///    <forms name="MyCookieName" cookieless="UseCookies"></forms>
192. </authentication><forms name="UserStatus"></forms>
193. </authentication> /// 删除指定的Cookie    <forms name="MyCookieName" cookieless="UseCookies"></forms>
194. </authentication><forms name="UserStatus"></forms>
195. </authentication>///    <forms name="MyCookieName" cookieless="UseCookies"></forms>
196. </authentication><forms name="UserStatus"></forms>
197. </authentication> ///    <forms name="MyCookieName" cookieless="UseCookies"></forms>
198. </authentication><forms name="UserStatus"></forms>
199. </authentication> public static void DeleteCookie(string name)    <forms name="MyCookieName" cookieless="UseCookies"></forms>
200. </authentication><forms name="UserStatus"></forms>
201. </authentication>{    <forms name="MyCookieName" cookieless="UseCookies"></forms>
202. </authentication><forms name="UserStatus"></forms>
203. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
204. </authentication><forms name="UserStatus"></forms>
205. </authentication>if( string.IsNullOrEmpty(name) )    <forms name="MyCookieName" cookieless="UseCookies"></forms>
206. </authentication><forms name="UserStatus"></forms>
207. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
208. </authentication><forms name="UserStatus"></forms>
209. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
210. </authentication><forms name="UserStatus"></forms>
211. </authentication>throw new ArgumentNullException("name");    <forms name="MyCookieName" cookieless="UseCookies"></forms>
212. </authentication><forms name="UserStatus"></forms>
213. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
214. </authentication><forms name="UserStatus"></forms>
215. </authentication>HttpCookie cookie = new HttpCookie(name);    <forms name="MyCookieName" cookieless="UseCookies"></forms>
216. </authentication><forms name="UserStatus"></forms>
217. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
218. </authentication><forms name="UserStatus"></forms>
219. </authentication>// 删除Cookie，其实就是设置一个【过期的日期】    <forms name="MyCookieName" cookieless="UseCookies"></forms>
220. </authentication><forms name="UserStatus"></forms>
221. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
222. </authentication><forms name="UserStatus"></forms>
223. </authentication>cookie.Expires = new DateTime(1900, 1, 1);    <forms name="MyCookieName" cookieless="UseCookies"></forms>
224. </authentication><forms name="UserStatus"></forms>
225. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
226. </authentication><forms name="UserStatus"></forms>
227. </authentication>HttpContext.Current.Response.Cookies.Add(cookie);    <forms name="MyCookieName" cookieless="UseCookies"></forms>
228. </authentication><forms name="UserStatus"></forms>
229. </authentication>}}

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更完整的代码可以从本文的示例代码中获得。（文章底部有下载地址）
使用方式：

1. public static class TestClass{    <forms name="MyCookieName" cookieless="UseCookies"></forms>
2. </authentication><forms name="UserStatus"></forms>
3. </authentication>public static void Write()    <forms name="MyCookieName" cookieless="UseCookies"></forms>
4. </authentication><forms name="UserStatus"></forms>
5. </authentication>{    <forms name="MyCookieName" cookieless="UseCookies"></forms>
6. </authentication><forms name="UserStatus"></forms>
7. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
8. </authentication><forms name="UserStatus"></forms>
9. </authentication>string str = "中国";    <forms name="MyCookieName" cookieless="UseCookies"></forms>
10. </authentication><forms name="UserStatus"></forms>
11. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
12. </authentication><forms name="UserStatus"></forms>
13. </authentication>int aa = 25;    <forms name="MyCookieName" cookieless="UseCookies"></forms>
14. </authentication><forms name="UserStatus"></forms>
15. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
16. </authentication><forms name="UserStatus"></forms>
17. </authentication>DisplaySettings setting = new DisplaySettings { Style = 3, Size = 50 };    <forms name="MyCookieName" cookieless="UseCookies"></forms>
18. </authentication><forms name="UserStatus"></forms>
19. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
20. </authentication><forms name="UserStatus"></forms>
21. </authentication>DateTime dt = new DateTime(2012, 1, 1, 12, 0, 0);    <forms name="MyCookieName" cookieless="UseCookies"></forms>
22. </authentication><forms name="UserStatus"></forms>
23. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
24. </authentication><forms name="UserStatus"></forms>
25. </authentication>str.WriteCookie("Key1", DateTime.Now.AddDays(1d));    <forms name="MyCookieName" cookieless="UseCookies"></forms>
26. </authentication><forms name="UserStatus"></forms>
27. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
28. </authentication><forms name="UserStatus"></forms>
29. </authentication>aa.WriteCookie("Key2", null);    <forms name="MyCookieName" cookieless="UseCookies"></forms>
30. </authentication><forms name="UserStatus"></forms>
31. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
32. </authentication><forms name="UserStatus"></forms>
33. </authentication>setting.ToJson().WriteCookie("Key3", null);    <forms name="MyCookieName" cookieless="UseCookies"></forms>
34. </authentication><forms name="UserStatus"></forms>
35. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
36. </authentication><forms name="UserStatus"></forms>
37. </authentication>dt.WriteCookie("Key4", null);    <forms name="MyCookieName" cookieless="UseCookies"></forms>
38. </authentication><forms name="UserStatus"></forms>
39. </authentication>}    <forms name="MyCookieName" cookieless="UseCookies"></forms>
40. </authentication><forms name="UserStatus"></forms>
41. </authentication>public static void Read()    <forms name="MyCookieName" cookieless="UseCookies"></forms>
42. </authentication><forms name="UserStatus"></forms>
43. </authentication>{    <forms name="MyCookieName" cookieless="UseCookies"></forms>
44. </authentication><forms name="UserStatus"></forms>
45. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
46. </authentication><forms name="UserStatus"></forms>
47. </authentication>HttpRequest request = HttpContext.Current.Request;    <forms name="MyCookieName" cookieless="UseCookies"></forms>
48. </authentication><forms name="UserStatus"></forms>
49. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
50. </authentication><forms name="UserStatus"></forms>
51. </authentication>string str = request.Cookies["Key1"].GetString();    <forms name="MyCookieName" cookieless="UseCookies"></forms>
52. </authentication><forms name="UserStatus"></forms>
53. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
54. </authentication><forms name="UserStatus"></forms>
55. </authentication>int num = request.Cookies["Key2"].ToInt(0);    <forms name="MyCookieName" cookieless="UseCookies"></forms>
56. </authentication><forms name="UserStatus"></forms>
57. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
58. </authentication><forms name="UserStatus"></forms>
59. </authentication>DisplaySettings setting = request.Cookies["Key3"].FromJson();    <forms name="MyCookieName" cookieless="UseCookies"></forms>
60. </authentication><forms name="UserStatus"></forms>
61. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
62. </authentication><forms name="UserStatus"></forms>
63. </authentication>DateTime dt = request.Cookies["Key4"].ConverTo();    <forms name="MyCookieName" cookieless="UseCookies"></forms>
64. </authentication><forms name="UserStatus"></forms>
65. </authentication>}    <forms name="MyCookieName" cookieless="UseCookies"></forms>
66. </authentication><forms name="UserStatus"></forms>
67. </authentication>}

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注意哦：以上代码中都是直接使用字符串"Key"的形式，这种方式对于大一些的程序在后期可能会影响维护。
所以建议：将访问Cookie所使用的Key能有一个类来统一的定义，或者将读写操作包装成一些属性放在一个类中统一的管理。

1. public static class CookieValues{    <forms name="MyCookieName" cookieless="UseCookies"></forms>
2. </authentication><forms name="UserStatus"></forms>
3. </authentication>// 建议把Cookie相关的参数放在一起，提供 get / set 属性（或者方法）来访问，以避免"key"到处乱写    <forms name="MyCookieName" cookieless="UseCookies"></forms>
4. </authentication><forms name="UserStatus"></forms>
5. </authentication>public static string AAA    <forms name="MyCookieName" cookieless="UseCookies"></forms>
6. </authentication><forms name="UserStatus"></forms>
7. </authentication>{    <forms name="MyCookieName" cookieless="UseCookies"></forms>
8. </authentication><forms name="UserStatus"></forms>
9. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
10. </authentication><forms name="UserStatus"></forms>
11. </authentication>get { return HttpContext.Current.Request.Cookies["Key1"].GetString(); }    <forms name="MyCookieName" cookieless="UseCookies"></forms>
12. </authentication><forms name="UserStatus"></forms>
13. </authentication>}    <forms name="MyCookieName" cookieless="UseCookies"></forms>
14. </authentication><forms name="UserStatus"></forms>
15. </authentication>public static int BBB    <forms name="MyCookieName" cookieless="UseCookies"></forms>
16. </authentication><forms name="UserStatus"></forms>
17. </authentication>{    <forms name="MyCookieName" cookieless="UseCookies"></forms>
18. </authentication><forms name="UserStatus"></forms>
19. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
20. </authentication><forms name="UserStatus"></forms>
21. </authentication>get { return HttpContext.Current.Request.Cookies["Key2"].ToInt(0); }    <forms name="MyCookieName" cookieless="UseCookies"></forms>
22. </authentication><forms name="UserStatus"></forms>
23. </authentication>}    <forms name="MyCookieName" cookieless="UseCookies"></forms>
24. </authentication><forms name="UserStatus"></forms>
25. </authentication>public static DisplaySettings CCC    <forms name="MyCookieName" cookieless="UseCookies"></forms>
26. </authentication><forms name="UserStatus"></forms>
27. </authentication>{    <forms name="MyCookieName" cookieless="UseCookies"></forms>
28. </authentication><forms name="UserStatus"></forms>
29. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
30. </authentication><forms name="UserStatus"></forms>
31. </authentication>get { return HttpContext.Current.Request.Cookies["Key3"].FromJson(); }    <forms name="MyCookieName" cookieless="UseCookies"></forms>
32. </authentication><forms name="UserStatus"></forms>
33. </authentication>}    <forms name="MyCookieName" cookieless="UseCookies"></forms>
34. </authentication><forms name="UserStatus"></forms>
35. </authentication>public static DateTime DDD    <forms name="MyCookieName" cookieless="UseCookies"></forms>
36. </authentication><forms name="UserStatus"></forms>
37. </authentication>{    <forms name="MyCookieName" cookieless="UseCookies"></forms>
38. </authentication><forms name="UserStatus"></forms>
39. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
40. </authentication><forms name="UserStatus"></forms>
41. </authentication>get { return HttpContext.Current.Request.Cookies["Key4"].ConverTo(); }    <forms name="MyCookieName" cookieless="UseCookies"></forms>
42. </authentication><forms name="UserStatus"></forms>
43. </authentication>}}

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补充

根据一些朋友提供的反馈，这里再补充4个需要注意的地方：
1. 如果使用Form登录验证且希望使用Cookie方式时，建议设置 cookieless="UseCookies"，因为这个参数的默认值是：cookieless="UseDeviceProfile"，Asp.net可能会误判。dudu就吃过亏。

1.     <forms name="MyCookieName" cookieless="UseCookies"></forms>
2. </authentication><forms name="UserStatus"></forms>
3. </authentication>

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2. Cookie有3个属性，一般我们可以不用设置，但它们的值可以在Web.config中指定默认值：

1. [/code]3. 虽然在写Cookie时，我们可以设置name, value之外的其它属性，但是在读取时，是读不到这些设置的。其实在我的示例代码中有体现，我前面也忘记了说明了。
2. 4. HttpRequest.Cookies 与 HttpResponse.Cookies 会有关系（很奇怪吧）。
3. 以下代码演示了这个现象：
4. [code]protected void Page_Load(object sender, EventArgs e){    <forms name="MyCookieName" cookieless="UseCookies"></forms>
5. </authentication><forms name="UserStatus"></forms>
6. </authentication>DateTime.Now.ToString().WriteCookie("t1", null);    <forms name="MyCookieName" cookieless="UseCookies"></forms>
7. </authentication><forms name="UserStatus"></forms>
8. </authentication>label1.Text = ShowAllCookies();    <forms name="MyCookieName" cookieless="UseCookies"></forms>
9. </authentication><forms name="UserStatus"></forms>
10. </authentication>Guid.NewGuid().ToString().WriteCookie("t2", null);    <forms name="MyCookieName" cookieless="UseCookies"></forms>
11. </authentication><forms name="UserStatus"></forms>
12. </authentication>// 如果去掉下面代码，将会看到2个t1    <forms name="MyCookieName" cookieless="UseCookies"></forms>
13. </authentication><forms name="UserStatus"></forms>
14. </authentication> Response.Cookies.Remove("t1");    <forms name="MyCookieName" cookieless="UseCookies"></forms>
15. </authentication><forms name="UserStatus"></forms>
16. </authentication>Response.Cookies.Remove("t2");}private string ShowAllCookies(){    <forms name="MyCookieName" cookieless="UseCookies"></forms>
17. </authentication><forms name="UserStatus"></forms>
18. </authentication>StringBuilder sb = new StringBuilder();    <forms name="MyCookieName" cookieless="UseCookies"></forms>
19. </authentication><forms name="UserStatus"></forms>
20. </authentication>for( int i = 0; i < Request.Cookies.Count; i++ ) {    <forms name="MyCookieName" cookieless="UseCookies"></forms>
21. </authentication><forms name="UserStatus"></forms>
22. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
23. </authentication><forms name="UserStatus"></forms>
24. </authentication>HttpCookie cookie = Request.Cookies[i];    <forms name="MyCookieName" cookieless="UseCookies"></forms>
25. </authentication><forms name="UserStatus"></forms>
26. </authentication>    <forms name="MyCookieName" cookieless="UseCookies"></forms>
27. </authentication><forms name="UserStatus"></forms>
28. </authentication>sb.AppendFormat("{0}={1}
29. ", cookie.Name, cookie.Value);    <forms name="MyCookieName" cookieless="UseCookies"></forms>
30. </authentication><forms name="UserStatus"></forms>
31. </authentication>}    <forms name="MyCookieName" cookieless="UseCookies"></forms>
32. </authentication><forms name="UserStatus"></forms>
33. </authentication>return sb.ToString();}

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上面的试验代码将会一直显示 t1 的Cookie ，这里就不再贴图了。

本文的所有示例代码可以点击此处下载。
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