Java interrupt 中断

为什么要中断?

根据需要停止某些持续的方法,这些方法可以被中断,所以又被称为可中断方法,包括:

Object的wait(), wait(long), wait(long, int),

Thraed的sleep(long), sleep(long, int), join(), join(long), join(long, int),

InterruptibleChannel的io操作,

Selector的wakeup方法,

其他方法。

 

如何中断?

Thread的三个方法:

方法 功能 特点
public void interrupt() 中断当前线程 更新中断标记为true,抛出InterruptedException
public void static boolean isInterrupted() 检查线程中断标记 返回查中断标记,可用于判断是否被调用中断
public boolean interrupted() 检查线程中断标记,可能更新 返回中断标记,若为true则更新为false。

 

 

 

 

当线程被中断时,会将中断标记置为true,并抛出InterruptedException异常,当捕获到这个异常时,说明当前线程的中断方法被调用。

如果在可中断方法执行前,调用了interrupt()方法,那么当执行到可中断方法时,会立刻抛出InterruptedException。

线程中catch (InterruptedException ex)会导致中断标志被擦除。

示例

interrupt:

public static void main(String[] args) throws InterruptedException {

        Thread thread = new Thread() {
            @Override
            public void run() {
                while (true) {
                    try {
                        TimeUnit.MINUTES.sleep(2);
                    } catch (InterruptedException ex) {
                        System.out.println("I am interrupted");
                        
                    }

                }
            }
        };

        thread.start();
        TimeUnit.MICROSECONDS.sleep(2);
        thread.interrupt();       
}

 

output:
I am interrupted

interrupted:

public static void main(String[] args) throws InterruptedException {

        Thread thread = new Thread() {
            @Override
            public void run() {
                while (true) {
                    //移除sleep和try-catch,因为可中断方法中断时,会将中断标志置为false
                }
            }
        };

        thread.start();
        TimeUnit.MICROSECONDS.sleep(2);
        System.out.println("before invoke interrupte,thread is interrupted:" + thread.isInterrupted());
        thread.interrupt();
        System.out.println("after invoke interrupte is interrupted:" + thread.isInterrupted());       
}

 

output:
before invoke interrupte,thread is interrupted:false
after invoke interrupte is interrupted:true

iterrupted

public static void main(String[] args) throws InterruptedException {

        Thread thread = new Thread() {
            @Override
            public void run() {
                while (true) {
                    System.out.println("thread is interrupted:" + Thread.interrupted());
                }
            }
        };
        thread.setDaemon(true);
        thread.start();
        TimeUnit.MICROSECONDS.sleep(2);
        System.out.println("before invoke interrupte,thread is interrupted:" + thread.isInterrupted());
        thread.interrupt();
        System.out.println("after invoke interrupte is interrupted:" + thread.isInterrupted());
        TimeUnit.MICROSECONDS.sleep(1);
        System.out.println("finally thread is interrupted:" + thread.isInterrupted());

    }

 

输出:

output:
thread is interrupted:false
before invoke interrupte,thread is interrupted:false
thread is interrupted:false
after invoke interrupte is interrupted:true
thread is interrupted:true
thread is interrupted:false
finally thread is interrupted:false

可中断方法执行前调用interrupt

public static void main(String[] args) {

        System.out.println("thread is interrupted:" + Thread.interrupted());

        Thread.currentThread().interrupt();
        System.out.println("after interrupt,do something...");
        try {
            TimeUnit.MICROSECONDS.sleep(2);
        } 
        catch (InterruptedException e) {
            System.out.println("thread is interrupted:" + Thread.currentThread().isInterrupted());
        }
    }

 

输出:

thread is interrupted:false
after interrupt,do something...
thread is interrupted:false

 

posted on 2019-03-22 12:31  Lv Jianwei  阅读(...)  评论(...编辑  收藏

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