分布式锁实现----Mysql

使用场景：项目并发很低的时候可以用

Mysql锁的实现：

通过ThreadLocal进行参数传递

@Service
@Data
public class MysqlLock implements Lock {

	@Autowired
	private TblOrderLockDao mapper;
	
	private ThreadLocal<TblOrderLock> orderLockThreadLocal ;

	@Override
	public void lock() {
		// 1、尝试加锁
		if(tryLock()) {
			System.out.println("尝试加锁");
			return;
		}
		// 2.休眠
		try {
			Thread.sleep(3);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		// 3.递归再次调用
		lock();
	}
	
	/**
	 * 	非阻塞式加锁，成功，就成功，失败就失败。直接返回
	 */
	@Override
	public boolean tryLock() {
		try {
			TblOrderLock tblOrderLock = orderLockThreadLocal.get();
			mapper.insertSelective(tblOrderLock);
			System.out.println("加锁对象："+orderLockThreadLocal.get());
			return true;
		}catch (Exception e) {
			return false;
		}
	}
	@Override
	public void unlock() {
		mapper.deleteByPrimaryKey(orderLockThreadLocal.get().getOrderId());
		System.out.println("解锁对象："+orderLockThreadLocal.get());
		orderLockThreadLocal.remove();
	}
}

业务逻辑

public class GrabMysqlLockServiceImpl implements GrabService{
	@Autowired
    private MysqlLock lock;
    @Autowired
    OrderService orderService;
    ThreadLocal<TblOrderLock> orderLock = new ThreadLocal<>();
    @Override
    public String grabOrder(int orderId, int driverId) {
        //生成 锁
        //生成key
        TblOrderLock ol = new TblOrderLock();
        ol.setOrderId(orderId);
        ol.setDriverId(driverId);

        orderLock.set(ol);
        lock.setOrderLockThreadLocal(orderLock);

        // lock ----------
        lock.lock();
        
        //执行业务
        try{
            System.out.println("司机:"+driverId+" 执行抢单逻辑");
            boolean b = orderService.grab(orderId, driverId);
            if(b) {
                System.out.println("司机:"+driverId+" 抢单成功");
            }else{
                System.out.println("司机:"+driverId+" 抢单失败");
            }
        }finally{
            //释放锁
            lock.unlock();
        }
        return null;
    }
}