Thread interrupt理解

Java线程中断机制详解

最新推荐文章于 2024-06-01 10:31:07 发布

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本文详细解析了Java中线程中断机制的工作原理，包括如何使用interrupt方法尝试中断线程，以及线程如何通过检查自身中断状态来决定是否停止运行。文章还探讨了在不同阻塞状态下线程对中断响应的行为差异，并提供了两个示例代码帮助理解。

一个线程可用调用另一个线程的interrupt方法来试图中断另一个的运行，线程也可以中断自己，如果线程没有运行，则interrupt将不会有任何影响。当一个线程试图中断另外一个线程时，checkAccess方法会被调用来判断访问权限。之所以说是试图，是因为一个线程不能绝对中断另一个线程，interrupt只是做一个标记，需要线程自己来处理是否停止。
如果被中断的线程正在处于wait,join,sleep状态，那么该线程立即接受到InterruptedException异常，该异常会自动清除线程的中断状态。If this thread is blocked in an I/O operation upon an interruptible channel then the channel will be closed, the thread's interrupt status will be set, and the thread will receive a ClosedByInterruptException.If this thread is blocked in a Selector then the thread's interrupt status will be set and it will return immediately from the selection operation, possibly with a non-zero value, just as if the selector's wakeup method were invoked.
interrupted，测试线程是否被中断，如果中断，会自动清理中断状态
isInterrupted测试线程是否被中断，如果中断，不会自动清理中断状态
当被中断的线程没有wait,join,blocking io,selector堵塞时，中断状态不会对正在运行的线程有任何影响，需要线程主体方法代码自行处理。举例：
例子一，线程将不会有任何影响，会一直运行

public class App {
    public static void main(String[] args) throws IOException {
	Thread t = new MyThread();
	t.start();
	
	System.out.println("wait to run thread");
	System.in.read();
	
	System.out.println("wait to end thread");
	t.interrupt();
	
	System.out.println("wait to end program");
	System.in.read();
	
	
    }

    private static class MyThread extends Thread {
	long last = 0;

	public void run() {
	    while (true) {
//		if(this.isInterrupted()){
//		    System.out.println("thread interupted");
//		    return;
//		}
		long cur = System.currentTimeMillis();
		if (last == 0) {
		    last = cur;
		    System.out.println("begin******************");
		} else {
		    if (cur - last > 5 * 1000) {
			last = cur;
			System.out.println(cur);
		    }
		}
	    }
	}
    }
}

例子二：线程自行退出

public class App {
    public static void main(String[] args) throws IOException {
	Thread t = new MyThread();
	t.start();
	
	System.out.println("wait to run thread");
	System.in.read();
	
	System.out.println("wait to end thread");
	t.interrupt();
	
	System.out.println("wait to end program");
	System.in.read();
	
	
    }

    private static class MyThread extends Thread {
	long last = 0;

	public void run() {
	    while (true) {
		if(this.isInterrupted()){
		    System.out.println("thread interupted");
		    return;
		}
		long cur = System.currentTimeMillis();
		if (last == 0) {
		    last = cur;
		    System.out.println("begin******************");
		} else {
		    if (cur - last > 5 * 1000) {
			last = cur;
			System.out.println(cur);
		    }
		}
	    }
	}
    }
}