聊聊Java 中的线程中断

Z时代
2024-01-10
分类：综合

Java如何实现线程中断？

通过调用Thread类的实例方法interrupt。如下：


Thread thread = new Thread(){
      @Override
      public void run() {
        if(isInterrupted()){
          System.out.println("interrupt");
        }
      }
    };
    thread.start();
    thread.interrupt();

线程中断后线程会立即停止执行吗？

NO。而如果线程未阻塞，或未关心中断状态，则线程会正常执行，不会被打断。

Thread.interrupt()的官方解释是这样的：

If this thread is blocked in an invocation of the
Object#wait() wait(), { Object#wait(long) wait(long)}, or { Object#wait(long, int) 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}.

也就是：处于阻塞的线程，即在执行Object对象的wait()、wait(long)、wait(long, int)，或者线程类的join()、join(long)、join(long, int)、sleep(long)、sleep(long,int)方法后线程的状态，当线程调用interrupt()方法后，这些方法将抛出InterruptedException异常，并清空线程的中断状态。

比如下面的例子会中断两次，第一次sleep方法收到中断信号后抛出了InterruptedException，捕获异常后中断状态清空，然后继续执行下一次：


public static void main(String[] args) throws InterruptedException {
    Thread thread = new Thread(){
      @Override
      public void run() {
        try {
          Thread.sleep(10000);
        } catch (InterruptedException e) {
          e.printStackTrace();
        }
        System.out.println("interrupt");
        try {
          Thread.sleep(10000);
        } catch (InterruptedException e) {
          e.printStackTrace();
        }
      }
    };
    thread.start();
    thread.interrupt();
    Thread.sleep(5000);
    thread.interrupt();
  }

而下面这个例子则会一直执行，不会被打断：


public static void main(String[] args) throws InterruptedException {
    Thread thread = new Thread(){
      @Override
      public void run() {
        while (true)
        System.out.println("interrupt");
      }
    };
    thread.start();
    thread.interrupt();
  }

interrupted与isInterrupted方法啥区别？