实现一个简单的可重入锁

1.简单实现

实现Lock接口并实现其lock方法与unlock方法

//利用Lock接口实现一个可重入锁
public class ReLock implements Lock{

    private boolean isLock = false;  //锁是否被获取
    private int count = 0; //记录一个线程获取同一个锁的次数
    private Thread lockBy = null; //记录当前获取到锁的线程
    //获取锁
    @Override
    public synchronized void lock() {
        Thread currentThread = Thread.currentThread();
        while(isLock && currentThread!=lockBy){
            try {
                wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        isLock = true;
        lockBy = currentThread;
        count++;
    }

    //释放锁
    @Override
    public synchronized void unlock() {
        count--;
        if(count == 0) {
            isLock = false;
            notify();
        }

    }

    //实现其他方法
}

2.测试

public class ReLockTest {
    //创建自定义的可重入锁对象
    public ReLock lock = new ReLock();
    public int value = 0;
    public void getNext(){  //自定义锁测试方法
        //获取锁
        lock.lock();
        value++;
        try {
            Thread.sleep(100);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println(value);
        //释放锁
        lock.unlock();
    }
    public void ReLockA(){      //可重入测试方法
        //获取锁
        lock.lock();
        value++;
        ReLockB();      //可重入则正常运行
        System.out.println("A: "+value);
        //释放锁
        lock.unlock();
    }
    public void ReLockB(){
        //获取锁
        lock.lock();
        value++;
        System.out.println("B: "+value);
        //释放锁
        lock.unlock();
    }
    @Test
    public void test(){
        ReLockTest test = new ReLockTest();
        new Thread(new Runnable() {     //自定义锁测试线程1
            @Override
            public void run() {
                while(true){
                    test.getNext();
                    //test.ReLockA();   //可重入测试
                }
            }
        }).start();
        new Thread(new Runnable() {     //自定义锁测试线程2
            @Override
            public void run() {
                while(true){
                    test.getNext();
                }
            }
        }).start();


        try {
            Thread.sleep(10000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}