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
    public  Result 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);
    }
}