lock、tryLock和lockInterruptibly的差別

lock()：若lock被thread A取得，thread B会进入block状态，直到取得lock；
tryLock()：若当下不能取得lock，thread就会放弃，可以设置一个超时时间参数，等待多久获取不到锁就放弃；
lockInterruptibly()：跟lock()情況一下，但是thread B可以通过interrupt中断，放弃继续等待锁

 

lock 与 lockInterruptibly比较区别在于：lock 优先考虑获取锁，待获取锁成功后，才响应中断，而lockInterruptibly 优先考虑响应中断 

ReentrantLock.lockInterruptibly允许在等待时由其它线程调用等待线程的Thread.interrupt方法来中断等待线程的等待而直接返回，这时不用获取锁，而会抛出一个InterruptedException

ReentrantLock.lock方法不允许Thread.interrupt中断,即使检测到Thread.isInterrupted,一样会继续尝试获取锁，失败则继续休眠。只是在最后获取锁成功后再把当前线程置为interrupted状态,然后再中断线程

public class LockDemo {

    private ReentrantLock lock = new ReentrantLock();

    public static void main(String[] args) throws InterruptedException {
        final LockDemo lockDemo = new LockDemo();

        Thread threada = new Thread("Thread A") {
            @Override
            public void run() {
                lockDemo.doSomeThing3(Thread.currentThread());
            }
        };
        threada.start();

        Thread threadb = new Thread("Thread B") {
            @Override
            public void run() {
                lockDemo.doSomeThing3(Thread.currentThread());
            }
        };
        threadb.start();
        
        //threadb.interrupt();
    }

    public void doSomeThing1(Thread thread) {
        lock.lock();
        try {
            System.out.println(thread.getName() + "得到了锁.");
            Thread.sleep(1000);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            System.out.println(thread.getName() + "释放了锁.");
            lock.unlock();
        }
    }
    
    
    public void doSomeThing2(Thread thread) {
        if (lock.tryLock()) {
            try {
                System.out.println(thread.getName() + "得到了锁.");
                Thread.sleep(1000);
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                System.out.println(thread.getName() + "释放了锁.");
                lock.unlock();
            }
        } else {
            System.out.println(thread.getName() + "获取锁失败.");
        }
    }

    public void doSomeThing3(Thread thread) {
        try {
            lock.lockInterruptibly();
            System.out.println(thread.getName() + " 得到了锁.");
            Thread.sleep(6000);
        } catch (InterruptedException e1) {
            e1.printStackTrace();
            System.out.println(thread.getName() + " interrupted.");
        } finally {
            System.out.println(thread.getName() + " 释放了锁.");
            lock.unlock();
        }
    }

}