java reentrantlock详解 java reentrantlock用法

ReentrantLock(互斥锁，可重入锁)
使用：
ReentrantLock reentrantLock = new ReentrantLock();
reentrantLock.lock();//拿锁

boolean res = reentrantLock.tryLock();//拿到锁返回true,没拿到返回false

boolean res = reentrantLock.tryLock(100,TimeUnit.SECONDS);//100秒内拿到锁返回true,否则没拿到返回false

reentrantLock.unlock();//释放锁

例：
不使用ReentrantLock：

public class MyRunnable implements Runnable {

    private Integer id = 0;

    @Override
    public void run() {

        for (int i = 0; i < 100; i++) {
            System.out.println("我是 " + Thread.currentThread().getName() + " 的id: " + (++id));
        }

    }

}

public static void main(String[] args) {

    MyRunnable myRunnable = new MyRunnable();
    for (int i = 0; i < 50; i++) {
        new Thread(myRunnable).start();
    }

}

结果：

...
我是 Thread-27 的id: 4992
我是 Thread-27 的id: 4993
我是 Thread-27 的id: 4994
我是 Thread-48 的id: 4984
我是 Thread-48 的id: 4995
我是 Thread-19 的id: 4983

Process finished with exit code 0

使用ReentrantLock：

public class MyRunnable implements Runnable {

    private Integer id = 0;
    private ReentrantLock reentrantLock;

    public MyRunnable(ReentrantLock reentrantLock) {
        this.reentrantLock = reentrantLock;
    }

    @Override
    public void run() {
        try {
            if (reentrantLock.tryLock(10, TimeUnit.SECONDS)) {
                for (int i = 0; i < 100; i++) {
                    System.out.println("我是 " + Thread.currentThread().getName() + " 的id: " + (++id));
                }
                reentrantLock.unlock();
            }

        } catch (Exception e) {
            e.printStackTrace();
        }

    }

}

public static void main(String[] args) {
    ReentrantLock reentrantLock = new ReentrantLock();
    Object o = new Object();
    MyRunnable myRunnable = new MyRunnable(reentrantLock);
    for (int i = 0; i < 50; i++) {
        new Thread(myRunnable).start();
    }
}

结果：

...
我是 Thread-48 的id: 4996
我是 Thread-48 的id: 4997
我是 Thread-48 的id: 4998
我是 Thread-48 的id: 4999
我是 Thread-48 的id: 5000

Process finished with exit code 0