redis实现分布式锁1
在集群下的并发问题：业务流程：
具体实现：
ILock
点击查看代码package com.hmdp.utils;
public interface ILock {
// 获取锁
boolean tryLock(long timeoutSec);
// 释放锁
void unlock();
}SimpleRedisLock
点击查看代码package com.hmdp.utils;
import org.springframework.data.redis.core.StringRedisTemplate;
import java.util.concurrent.TimeUnit;
public class SimpleRedisLock implements ILock {
private String name;
private StringRedisTemplate stringRedisTemplate;
private static final String KEY_PREFIX = "lock:";
public SimpleRedisLock(String name, StringRedisTemplate stringRedisTemplate) {
this.name = name;
this.stringRedisTemplate = stringRedisTemplate;
}
@Override
public boolean tryLock(long timeoutSec) {
// 获取线程的标识
long threadId = Thread.currentThread().getId();
// 获取锁
Boolean success = stringRedisTemplate.opsForValue().setIfAbsent(KEY_PREFIX + name, threadId + "", timeoutSec, TimeUnit.SECONDS);
return Boolean.TRUE.equals(success);
}
@Override
public void unlock() {
// 释放锁
stringRedisTemplate.delete(KEY_PREFIX + name);
}
}VoucherOrderServiceImpl
点击查看代码package com.hmdp.service.impl;
import com.hmdp.dto.Result;
import com.hmdp.entity.SeckillVoucher;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.ISeckillVoucherService;
import com.hmdp.service.IVoucherOrderService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.RedisIdWorker;
import com.hmdp.utils.SimpleRedisLock;
import com.hmdp.utils.UserHolder;
import org.springframework.aop.framework.AopContext;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import javax.annotation.Resource;
import java.time.LocalDateTime;
/**
* <p>
*服务实现类
* </p>
*
* @author ztn
* @since 2025-09-23
*/
@Service
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {
@Resource
private ISeckillVoucherService seckillVoucherService;
@Resource
private RedisIdWorker redisIdWorker;
@Resource
private StringRedisTemplate stringRedisTemplate;
@Override
public Result seckillVocher(Long voucherId) {
// 1.查询优惠券
SeckillVoucher voucher = seckillVoucherService.getById(voucherId);
// 2.判断秒杀是否开始
if(voucher.getBeginTime().isAfter(LocalDateTime.now())){
return Result.fail("秒杀尚未开始");
}
// 3.判断秒杀是否结束
if(voucher.getEndTime().isBefore(LocalDateTime.now())){
return Result.fail("秒杀已经结束");
}
// 4.判断库是否充足
if(voucher.getStock() < 1){
return Result.fail("库存不足");
}
Long userId = UserHolder.getUser().getId();
// 创建锁对象
SimpleRedisLock lock = new SimpleRedisLock("order:" + userId, stringRedisTemplate);
// 获取锁
boolean isLock = lock.tryLock(1200);
// 判断是否获取锁成功
if(!isLock){
// 获取锁失败，返回错误或重试
return Result.fail("不允许重复下单");
}
try {
// 获取代理对象（事务）
IVoucherOrderService proxy = (IVoucherOrderService) AopContext.currentProxy();
return proxy.createVoucherOrder(voucherId);
}finally {
// 释放锁
lock.unlock();
}
}
@Transactional
publicResult createVoucherOrder(Long voucherId) {
// 5.一人一单
Long userId = UserHolder.getUser().getId();
// 5.1 查询订单
int count = query().eq("user_id", userId).eq("voucher_id", voucherId).count();
// 5.2 判断是否存在
if(count > 0){
// 用户已经购买过了
return Result.fail("用户已经购买过一次了");
}
// 6.扣减库存
boolean success = seckillVoucherService.update()
.setSql("stock = stock - 1") // set stock =stock -1
.eq("voucher_id", voucherId)
// .eq("stock",voucher.getStock()) // where id = ? and stock = ?
.gt("stock",0) // where id = ? and stock > 0
.update();
if(!success){
return Result.fail("库存不足");
}
// 7.创建订单
VoucherOrder voucherOrder = new VoucherOrder();
// 7.1订单id
long orderId = redisIdWorker.nextId("order");
voucherOrder.setId(orderId);
// 7.2用户id
voucherOrder.setUserId(userId);
// 7.3代金券id
voucherOrder.setVoucherId(voucherId);
save(voucherOrder);
// 8.返回订单id
return Result.ok(orderId);
}
}
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