java-Thread的interrupt笔记

1.interrupt() 中断线程

     * <p> If this thread is blocked in an invocation of the {@link
     * Object#wait(long, int) wait(long, int)} methods of the {@link Object}
     * class, or of the {@link #join()}, {@link #join(long)}, {@link
     * #join(long, int)}, {@link #sleep(long)}, or {@link #sleep(long, int)},
     * methods of this class, then its interrupt status will be cleared and it
     * will receive an {@link InterruptedException}.

     * Object#wait() wait()}, {@link Object#wait(long) wait(long)}, or {@link


也就是只有在wait,join,sleep的时候才能抛出interruptedException,并且清除了中断状态,其他情况不会抛出中断异常

通过代码证明下

a.第一种情况 在不是wait,join,sleep的时候调用interrupt方法

public class Interrupt1 {

public static void main(String[] args) throws InterruptedException {
ThreadTest thread=new ThreadTest();
Thread t=new Thread(thread);
t.start();
Thread.sleep(1000);
t.interrupt();
System.out.println("main 线程执行完毕");
}

public static class ThreadTest implements Runnable{

public void run() {
Thread curr=Thread.currentThread();
System.out.println("===="+curr.isInterrupted());
while(true){
if(curr.isInterrupted()){
System.out.println("===="+curr.isInterrupted());
break;
}

if(1==2)
break;
}
System.out.println("^^^^^^^");
}

}
}

执行结果：

====false

main 线程执行完毕

====true

^^^^^^^

从结果可以看出并没有抛出interruptException，并且curr.isInterrupted方法返回了ture，说明中断状态也没有被清除

b.在sleep的时候在调用interrupte方法看下什么情况，run方法加下sleep

Thread curr=Thread.currentThread();
System.out.println("===="+curr.isInterrupted());
while(true){

try {
Thread.sleep(200);
} catch (InterruptedException e) {
e.printStackTrace();
System.out.println("==="+curr.isInterrupted());
}

if(curr.isInterrupted())
System.out.println("000000000");

if(1==2)
break;
}
System.out.println("^^^^^^^");

执行结果：
====false

main 线程执行完毕

java.lang.InterruptedException: sleep interrupted

===false
at java.lang.Thread.sleep(Native Method)
at a.Interrupt1$ThreadTest.run(Interrupt1.java:22)
at java.lang.Thread.run(Unknown Source)

确实抛出了interruptedException,并且isinterrupted()返回了false说明中断状态被清除了，后面的判断就不管用了，所以拿这个方法中断线程还是不安全，自己用变量控制更靠谱

2.静态方法public static boolean
interrupted()
     * Tests whether the current thread has been interrupted.  The
     * <i>interrupted status</i> of the thread is cleared by this method.  In
     * other words, if this method were to be called twice in succession, the
     * second call would return false (unless the current thread were
     * interrupted again, after the first call had cleared its interrupted
     * status and before the second call had examined it).

检查当前中断状态，并且清除中断状态，连续调用2此的第二次肯定返回false

Thread curr=Thread.currentThread();
System.out.println("===="+curr.isInterrupted());
while(true){

try {
Thread.sleep(200);
} catch (InterruptedException e) {
e.printStackTrace();
curr.interrupt();
System.out.println("先变成true==="+curr.isInterrupted());
System.out.println("curr.isInterrupted==="+Thread.interrupted());
System.out.println("中断状态清除:"+curr.isInterrupted());
System.out.println("curr.isInterrupted==="+Thread.interrupted());
System.out.println("====c"+curr.isInterrupted());
}

if(curr.isInterrupted())
System.out.println("000000000");

if(1==2)
break;
}
System.out.println("^^^^^^^");
}

执行结果:
====false

main 线程执行完毕

java.lang.InterruptedException: sleep interrupted

先变成true===true

curr.isInterrupted===true

====bfalse

curr.isInterrupted===false

====cfalse
at java.lang.Thread.sleep(Native Method)
at a.Interrupt1$ThreadTest.run(Interrupt1.java:22)
at java.lang.Thread.run(Unknown Source)

内部调用是这样的
    public boolean isInterrupted() {

        return isInterrupted(false);

    }
    public static boolean interrupted() {

        return currentThread().isInterrupted(true);

    }
private native boolean isInterrupted(boolean ClearInterrupted);
isInterrupted不清除，静态方法的清除