interrupt()、interrupted()方法的使用和线程退出的时机

    当你在线程上调用interrupt()时，线程中断发生的唯一时刻是在任务要进入到可中断的阻塞操作（如sleep,wait, join等）中，或者已经在阻塞操作内部时。此时线程会抛出InterruptedException，并从异常中退出。如果run()方法内部恰巧没有可以产生阻塞的部分，则run()方法可能就无法被interrupt方法中断。此时，可以调用interrupted()方法判断线程的终止状态，并根据状态控制线程的中断。

  
    

   
     package
   
      Concurrent;


   
     import
   
      java.util.concurrent.ExecutorService;

   
     import
   
      java.util.concurrent.Executors;


   
     class
   
      InterruptedClass 
   
     implements
   
      Runnable {
 @Override
 
   
     public
   
      
   
     void
   
      run() {
 
   
     double
   
      d 
   
     =
   
      
   
     0.0f
   
     ;
 
   
     try
   
      {
 
   
     while
   
     (
   
     !
   
     Thread.interrupted()) {
 System.out.println(
   
     "
   
     Running in InterrupedClass
   
     "
   
     );
 
   
     //
   
      before sleep, point 1
   
     

   
      Thread.sleep(
   
     2000
   
     );
 
   
     //
   
      before calculating, point 2
   
     

   
      System.out.println(
   
     "
   
     Calculating...
   
     "
   
     );
 
   
     for
   
      (
   
     int
   
      i 
   
     =
   
      
   
     0
   
     ; i 
   
     <
   
      
   
     900000
   
     ; i
   
     ++
   
     ) { 
 d 
   
     =
   
      d 
   
     +
   
      (Math.PI 
   
     +
   
      Math.E) 
   
     /
   
      d; 
 } 
 System.out.println(
   
     "
   
     After calculating
   
     "
   
     );
 }
 }
   
     catch
   
     (InterruptedException e) {
 System.out.println(
   
     "
   
     Exiting via InterruptedException
   
     "
   
     );
 }
   
     finally
   
      {
 System.out.println(
   
     "
   
     In finally!
   
     "
   
     );
 }
 }
}


   
     public
   
      
   
     class
   
      Interrupt {

 
   
     public
   
      
   
     static
   
      
   
     void
   
      main(String[] args) 
   
     throws
   
      Exception {
 ExecutorService exec 
   
     =
   
      Executors.newCachedThreadPool();
 exec.execute(
   
     new
   
      InterruptedClass());
 
 Thread.sleep(
   
     1000
   
     ); 
   
     //
   
      如果睡眠1000ms，则在point1处之前就调用了shutdownNow，即调用了interrupt
 
   
     //
   
      因此再调用sleep方法时会抛出异常并从catch处退出
 
 
   
     //
   
     Thread.sleep(2001); 
   
     //
   
      如果睡眠2001ms，则在point2处调用interrupt，即在正常运行处调用interrupt
 
   
     //
   
      因此会执行完循环中的大数计算，再词运行到while(!Thread.interrupted())处
 
   
     //
   
      时才回中断，退出while，不抛出异常
 
 
   
     //
   
      finally或catch中可以添加释放占用资源的代码
   
     

   
      exec.shutdownNow();
 }

}