【面经】interrupt()、interrupted()和isInterrupted()的区别与使用

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interrupt方法

如果打断线程正在sleep，wait，join会导致被打断的线程抛出InterruptedException，并清除打断标记。如果打断正在运行的线程，则会设置打断标记。park的线程被打断也会被设置打断标记

Interrupted方法

Thread类的静态方法。检测当前线程的中断标记，返回一个boolean并清除中断状态，其连续两次调用的返回结果不一样，因为第二次调用的时候，线程的中断状态已经被清除了，会返回一个false.

isInterrupted()方法

测试线程是否被打断，不会清除中断状态。

演示代码

场景：在sleep时打断

package jvm;import lombok.extern.slf4j.Slf4j;import java.util.logging.Logger;public class TestInterrupt {public static void main(String[] args) throws InterruptedException {MyThread t1=new MyThread();t1.start();Thread.sleep(10000);t1.interrupt();}}
class MyThread extends Thread{@Overridepublic void run() {while (!this.isInterrupted()){try {System.out.println("执行1s");Thread.sleep(1000);} catch (InterruptedException e) {System.out.println("在睡觉的时候被打断了");throw new RuntimeException(e);}}}
}

如上：导致被打断的线程抛出InterruptedException，并清除打断标记。

场景：在正常运行时，打断标记的情况

package jvm;import lombok.extern.slf4j.Slf4j;import java.util.logging.Logger;public class TestInterrupt {public static void main(String[] args) throws InterruptedException {MyThread t1=new MyThread();t1.start();Thread.sleep(10000);t1.interrupt();}}
class MyThread extends Thread {@Overridepublic void run() {while (!this.isInterrupted()) {System.out.println("执行1s");System.out.println("标记" + this.isInterrupted());}}
}

如上：正常运行时被打断是不会被清除标记的。

场景：使用park暂停的线程打断标记情况

package jvm;import lombok.extern.slf4j.Slf4j;import java.util.concurrent.locks.LockSupport;
import java.util.logging.Logger;public class TestInterrupt {public static void main(String[] args) throws InterruptedException {MyThread t1=new MyThread();t1.start();Thread.sleep(10000);t1.interrupt();}}
class MyThread extends Thread {@Overridepublic void run() {while (!this.isInterrupted()) {LockSupport.park();System.out.println("标记" + this.isInterrupted());}}
}

如上：park被暂停的线程被打断是不会清除标记的。

场景：测试Thread.interrupted静态方法

package jvm;import lombok.extern.slf4j.Slf4j;import java.util.concurrent.locks.LockSupport;
import java.util.logging.Logger;public class TestInterrupt {public static void main(String[] args) throws InterruptedException {MyThread t1=new MyThread();t1.start();Thread.sleep(10000);t1.interrupt();}}
class MyThread extends Thread {@Overridepublic void run() {while (true){boolean interrupted = Thread.interrupted();System.out.println("标记:"+interrupted);if(interrupted){break;}}}
}