线程的interrupt()

官网解释

意思是当线程被blocked的时候可以被打断，wait()、sleep()、join()时被打断会抛出InterruptedException异常。

演示sleep()被打断

        Thread t1 = new Thread() {
            @Override
            public void run() {
                while (true) {
                    System.out.println("running...");
                    try {
                        Thread.sleep(100L);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                        break;
                    }
                }
            }
        };

        t1.start();
        Thread.sleep(100L);
        System.out.println(t1.isInterrupted());
        t1.interrupt();
        System.out.println(t1.isInterrupted());

在sleep()被打断在异常中要执行break;打断循环，否则该循环一直在执行

演示wait()被打断

package com.dwz.concurrency.chapter6;

public class ThreadInterrupt {
    private static final Object MONITOR = new Object();
    public static void main(String[] args) throws InterruptedException {
        Thread t2 = new Thread() {
            @Override
            public void run() {
                while (true) {
                    System.out.println("running...");
                    synchronized (MONITOR) {
                        try {
                            MONITOR.wait(100L);
                        } catch (InterruptedException e) {
                            System.out.println("收到打断信号。。。");
                            e.printStackTrace();
                            break;
                        }
                    }
                }
            }
        };

        t2.start();
        Thread.sleep(100L);
        System.out.println(t2.isInterrupted());
        t2.interrupt();
        System.out.println(t2.isInterrupted());
    }
}

1.跟sleep()一样，wait()被打断时在异常中要执行break;打断循环，否则该循环一直在执行

2.wait()的调用者一定是一个对象

演示join()被打断

package com.dwz.concurrency.chapter6;

public class ThreadInterrupt3 {
    public static void main(String[] args) throws InterruptedException  {
        Thread main = Thread.currentThread();
        Thread t1 = new Thread() {
            @Override
            public void run() {
                while (true) {

                }
            }
        };

        t1.start();

        System.out.println("main: " + main.getName());
        Thread t2 = new Thread() {
            @Override
            public void run() {
                try {
                    Thread.sleep(1000L);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println("t2: " + Thread.currentThread().getName());
                main.interrupt();
                System.out.println("interrupt...");
            }
        };
        t2.start();

        try {
            t1.join();
        } catch (InterruptedException e) {
            e.printStackTrace();
            t1.interrupt();
        }

        System.out.println("main isInterrupted:" + main.isInterrupted());
        System.out.println("t1 isInterrupted:" + t1.isInterrupted());
        while(!t1.isInterrupted()) {
            Thread.sleep(1000L);
            System.out.println(t1.isInterrupted());
        }
    }
}

1.我们要清楚，join的对象是main线程，要想打断 t1.join(), 要在另一个线程中执行 main.interrupt()

2.isInterrupted()表示线程是否被打断，如果只执行 main.interrupt() 方法，意味着 t1.join()被打断，t1仍是未打断的，执行 t1.interrupt()才会改变t1状态

3. t1.join() 一定要在 t1.start() 和  t2.start() 之后被执行。