Java 多线程 join和interrupt 方法

简述：

使用Java多线程中join和interrupt函数

《Java编程思想》 P669 ~ P670

一个线程可以再其他线程上调用join()方法，其效果是等待一段时间直到第二个线程结束才继续执行。

如果某个线程在另一个线程t上调用t.join(), 此线程将被挂起, 直到目标线程t结束才恢复（即t.isAlive() 返回为假）

对join()方法的调用可以被中断, 做法是在调用线程上调用interrupt()方法，这时需要用到 try-catch 

Sleeper.java

package com.anialy.test.multithread.JoinAndInterrupt;

public class Sleeper extends Thread {
	private int duration;
	
	public Sleeper(String name, int sleepTime){
		setName(name);
		this.duration = sleepTime;
		start(); // 在构造函数中启动
	}
	
	@Override
	public void run() {
		try{
			sleep(duration);
		} catch(InterruptedException e){
			System.out.println(String.format("%s was interrupted. isInterrupted(): %b"
					, getName(), isInterrupted()));
			return;
		}
		System.out.println(getName() + " has awakened");
	}
}

Joiner.java

package com.anialy.test.multithread.JoinAndInterrupt;

public class Joiner extends Thread {
	private Sleeper sleeper;
	
	public Joiner(String name, Sleeper sleeper) {
		setName(name);
		this.sleeper = sleeper;
		start();
	}
	
	@Override
	public void run() {
		try {
			// 如果某个线程在另一个线程t上调用t.join(), 此线程将被挂起, 
			// 直到目标线程t结束才恢复（即t.isAlive() 返回为假）
			sleeper.join();
		} catch (InterruptedException e) {
			System.out.println("Interrupted.");
		}
		System.out.println(getName() + " join completed");
	}
}

Test1.java

package com.anialy.test.multithread.JoinAndInterrupt;

public class Test1 {
	public static void main(String[] args) {
		Sleeper sleeper1 = new Sleeper("线程A-1500", 1500);
		Joiner joiner1 = new Joiner("线程join-A", sleeper1);
	}
}

输出：

可以看到在第一条线程休眠1500毫秒之后，join-A的线程才完成

Test.java

package com.anialy.test.multithread.JoinAndInterrupt;

public class Test2 {
	public static void main(String[] args) {
		Sleeper sleeper = new Sleeper("线程A-1500", 1500);
		Joiner joiner = new Joiner("线程Join-A", sleeper);
		sleeper.interrupt();
	}
}

输出：

由于对sleeper线程使用了interrupt，sleeper没有完成之前，就已经中断了join()