你能解释一下调用java.lang.Thread.interrupt()时做什么吗?


当前回答

为了完整起见,除了其他答案外,如果线程在阻塞Object.wait(..)或thread .sleep(..)等之前被中断,这相当于在阻塞该方法时立即被中断,如下例所示。

public class InterruptTest {
    public static void main(String[] args) {

        Thread.currentThread().interrupt();

        printInterrupted(1);

        Object o = new Object();
        try {
            synchronized (o) {
                printInterrupted(2);
                System.out.printf("A Time %d\n", System.currentTimeMillis());
                o.wait(100);
                System.out.printf("B Time %d\n", System.currentTimeMillis());
            }
        } catch (InterruptedException ie) {
            System.out.printf("WAS interrupted\n");
        }
        System.out.printf("C Time %d\n", System.currentTimeMillis());

        printInterrupted(3);

        Thread.currentThread().interrupt();

        printInterrupted(4);

        try {
            System.out.printf("D Time %d\n", System.currentTimeMillis());
            Thread.sleep(100);
            System.out.printf("E Time %d\n", System.currentTimeMillis());
        } catch (InterruptedException ie) {
            System.out.printf("WAS interrupted\n");
        }
        System.out.printf("F Time %d\n", System.currentTimeMillis());

        printInterrupted(5);

        try {
            System.out.printf("G Time %d\n", System.currentTimeMillis());
            Thread.sleep(100);
            System.out.printf("H Time %d\n", System.currentTimeMillis());
        } catch (InterruptedException ie) {
            System.out.printf("WAS interrupted\n");
        }
        System.out.printf("I Time %d\n", System.currentTimeMillis());

    }
    static void printInterrupted(int n) {
        System.out.printf("(%d) Am I interrupted? %s\n", n,
                Thread.currentThread().isInterrupted() ? "Yes" : "No");
    }
}

输出:

$ javac InterruptTest.java 

$ java -classpath "." InterruptTest
(1) Am I interrupted? Yes
(2) Am I interrupted? Yes
A Time 1399207408543
WAS interrupted
C Time 1399207408543
(3) Am I interrupted? No
(4) Am I interrupted? Yes
D Time 1399207408544
WAS interrupted
F Time 1399207408544
(5) Am I interrupted? No
G Time 1399207408545
H Time 1399207408668
I Time 1399207408669

含义:如果你像下面这样循环,并且中断发生在控制已经离开Thread.sleep(..)并且正在循环的确切时刻,异常仍然会发生。因此,依赖InterruptedException在线程被中断后可靠地抛出是完全安全的:

while (true) {
    try {
        Thread.sleep(10);
    } catch (InterruptedException ie) {
        break;
    }
}

其他回答

thread. interrupt()将目标线程的中断状态/标志设置为true,当使用thread. interrupted()检查时,可以帮助停止无休止的线程。请参阅http://www.yegor256.com/2015/10/20/interrupted-exception.html

什么是中断?

中断是一个指示 线程应该停止它是什么 做和做别的事情。由 由程序员来决定 线程如何响应中断, 但这对于线程来说是很常见的 终止。

它是如何实现的?

实现了中断机制 使用内部标志 中断状态。调用 interrupt设置这个标志。当 线程通过检查中断 调用静态方法 中断状态 清除。非静态的 线程。被使用的isInterrupted 一个线程来查询中断 另一种状态,并不会改变 中断状态标志。

引用自Thread.interrupt() API:

Interrupts this thread. First the checkAccess method of this thread is invoked, which may cause a SecurityException to be thrown. If this thread is blocked in an invocation of the wait(), wait(long), or wait(long, int) methods of the Object class, or of the join(), join(long), join(long, int), sleep(long), or sleep(long, int), methods of this class, then its interrupt status will be cleared and it will receive an InterruptedException. 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. If none of the previous conditions hold then this thread's interrupt status will be set.

看看下面的内容,你就能完全理解:

http://download.oracle.com/javase/tutorial/essential/concurrency/interrupt.html

中断是对线程的一个指示,它应该停止正在做的事情并做其他事情。由程序员决定线程如何响应中断,但是线程终止是很常见的。 一个很好的参考:https://docs.oracle.com/javase/tutorial/essential/concurrency/interrupt.html

Thread.interrupt()方法设置内部的“中断状态”标志。通常该标志由Thread.interrupted()方法检查。

按照惯例,任何通过InterruptedException存在的方法都必须清除中断状态标志。

为了完整起见,除了其他答案外,如果线程在阻塞Object.wait(..)或thread .sleep(..)等之前被中断,这相当于在阻塞该方法时立即被中断,如下例所示。

public class InterruptTest {
    public static void main(String[] args) {

        Thread.currentThread().interrupt();

        printInterrupted(1);

        Object o = new Object();
        try {
            synchronized (o) {
                printInterrupted(2);
                System.out.printf("A Time %d\n", System.currentTimeMillis());
                o.wait(100);
                System.out.printf("B Time %d\n", System.currentTimeMillis());
            }
        } catch (InterruptedException ie) {
            System.out.printf("WAS interrupted\n");
        }
        System.out.printf("C Time %d\n", System.currentTimeMillis());

        printInterrupted(3);

        Thread.currentThread().interrupt();

        printInterrupted(4);

        try {
            System.out.printf("D Time %d\n", System.currentTimeMillis());
            Thread.sleep(100);
            System.out.printf("E Time %d\n", System.currentTimeMillis());
        } catch (InterruptedException ie) {
            System.out.printf("WAS interrupted\n");
        }
        System.out.printf("F Time %d\n", System.currentTimeMillis());

        printInterrupted(5);

        try {
            System.out.printf("G Time %d\n", System.currentTimeMillis());
            Thread.sleep(100);
            System.out.printf("H Time %d\n", System.currentTimeMillis());
        } catch (InterruptedException ie) {
            System.out.printf("WAS interrupted\n");
        }
        System.out.printf("I Time %d\n", System.currentTimeMillis());

    }
    static void printInterrupted(int n) {
        System.out.printf("(%d) Am I interrupted? %s\n", n,
                Thread.currentThread().isInterrupted() ? "Yes" : "No");
    }
}

输出:

$ javac InterruptTest.java 

$ java -classpath "." InterruptTest
(1) Am I interrupted? Yes
(2) Am I interrupted? Yes
A Time 1399207408543
WAS interrupted
C Time 1399207408543
(3) Am I interrupted? No
(4) Am I interrupted? Yes
D Time 1399207408544
WAS interrupted
F Time 1399207408544
(5) Am I interrupted? No
G Time 1399207408545
H Time 1399207408668
I Time 1399207408669

含义:如果你像下面这样循环,并且中断发生在控制已经离开Thread.sleep(..)并且正在循环的确切时刻,异常仍然会发生。因此,依赖InterruptedException在线程被中断后可靠地抛出是完全安全的:

while (true) {
    try {
        Thread.sleep(10);
    } catch (InterruptedException ie) {
        break;
    }
}