package com.hmdp.utils;
public interface ILock {
    /**
     * 嘗試獲取鎖
     * @param timeoutSec 鎖的持有時(shí)間，過(guò)期自動(dòng)釋放
     * @return true代表獲取鎖成功，false代表獲取鎖失敗。
     */
    boolean tryLock(long timeoutSec);
    /**
     * 釋放鎖
     */
    void unlock();
}

package com.hmdp.utils;
import org.springframework.data.redis.core.StringRedisTemplate;
import java.util.concurrent.TimeUnit;
/**
 * @Version 1.0
 */
public class SimpleRedisLock implements ILock {
    //Redis
    private StringRedisTemplate stringRedisTemplate;
    //業(yè)務(wù)名稱(chēng)，也就是鎖的名稱(chēng)
    private String name;
    public SimpleRedisLock(StringRedisTemplate stringRedisTemplate, String name) {
        this.stringRedisTemplate = stringRedisTemplate;
        this.name = name;
    }
    //key的前綴
    private static final String KEY_PREFIX = "lock:";
    @Override
    public boolean tryLock(long timeoutSec) {
        //獲取線(xiàn)程id，當(dāng)作set的value
        long threadId = Thread.currentThread().getId();
        Boolean success = stringRedisTemplate.opsForValue()
                .setIfAbsent(KEY_PREFIX + name, threadId+"", timeoutSec, TimeUnit.SECONDS);
        return Boolean.TRUE.equals(success);
    }
    //釋放鎖
    @Override
    public void unlock() {
        //刪除key
        stringRedisTemplate.delete(KEY_PREFIX+name);
    }
}

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>
 *  服務(wù)實(shí)現(xiàn)類(lèi)
 * </p>
 *
 */
@Service
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {
 
    @Resource
    private ISeckillVoucherService iSeckillVoucherService;
    @Resource
    private RedisIdWorker redisIdWorker;
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Override
    public Result seckillVoucher(Long voucherId) {
        //1.獲取優(yōu)惠券信息
        SeckillVoucher voucher = iSeckillVoucherService.getById(voucherId);
        //2.判斷是否已經(jīng)開(kāi)始
        if (voucher.getBeginTime().isAfter(LocalDateTime.now())){
            Result.fail("秒殺尚未開(kāi)始!");
        }
        //3.判斷是否已經(jīng)結(jié)束
        if (voucher.getEndTime().isBefore(LocalDateTime.now())){
            Result.fail("秒殺已經(jīng)結(jié)束了!");
        }
        //4.判斷庫(kù)存是否充足
        if (voucher.getStock() < 1) {
            Result.fail("庫(kù)存不充足!");
        }
        //5.扣減庫(kù)存
        boolean success = iSeckillVoucherService.update()
                .setSql("stock = stock-1").eq("voucher_id",voucherId).gt("stock",0)
                .update();
        if (!success){
            Result.fail("庫(kù)存不充足!");
        }
        Long userId = UserHolder.getUser().getId();
        //1.創(chuàng)建鎖對(duì)象
        SimpleRedisLock lock = new SimpleRedisLock(stringRedisTemplate, "order:" + userId);
        //2.嘗試獲取鎖
        boolean isLock = lock.tryLock(1200);
        if (!isLock){
            //獲取鎖失敗
            return Result.fail("一個(gè)用戶(hù)只能下一單！");
        }
        try {
            IVoucherOrderService proxy = (IVoucherOrderService) AopContext.currentProxy();
            return proxy.createVoucherOrder(voucherId);
        } finally {
            //釋放鎖
            lock.unlock();
        }
    }
    @Transactional
    public Result createVoucherOrder(Long voucherId) {
        Long userId = UserHolder.getUser().getId();
        //6.根據(jù)優(yōu)惠券id和用戶(hù)id判斷訂單是否已經(jīng)存在
        //如果存在，則返回錯(cuò)誤信息
        int count = query().eq("user_id", userId).eq("voucher_id", voucherId).count();
        if (count > 0) {
            return Result.fail("用戶(hù)已經(jīng)購(gòu)買(mǎi)！");
        }
        //7. 創(chuàng)建訂單
        VoucherOrder voucherOrder = new VoucherOrder();
        //7.1添加訂單id
        Long orderId = redisIdWorker.nextId("order");
        voucherOrder.setId(orderId);
        //7.2添加用戶(hù)id
        voucherOrder.setUserId(userId);
        //7.3添加優(yōu)惠券id
        voucherOrder.setVoucherId(voucherId);
        save(voucherOrder);
        //8.返回訂單id
        return Result.ok(orderId);
    }
}