线程中断

线程类的interrupt()方法可对某一线程进行中断，例子如下：

public class SleepBlocked implements Runnable{

	
	@Override
	public void run() {
		// TODO Auto-generated method stub
		try {
			TimeUnit.SECONDS.sleep(100);
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			System.out.println("Interupted Exception");
		}
		System.out.println("Exiting SleepBlocked.run()");
	}
}

=======================

public class Interrupting {

	private static ExecutorService exec=Executors.newCachedThreadPool();
	
	static void test(Runnable r) throws InterruptedException{
		Future<?> f=exec.submit(r);
		TimeUnit.MILLISECONDS.sleep(100);
		System.out.println("Interrupting "+r.getClass().getName());
		f.cancel(true); //中断运行的线程
						//cancel()方法是一种中断由Executor启动的单个线程的方式
		System.out.println("Interrupt set to "+r.getClass().getName());
	}
	
	public static void main(String[] args) throws InterruptedException{
		test(new SleepBlocked());
		//这里SleepBlocked是可中断的
                     TimeUnit.SECONDS.sleep(3);
		System.out.println("Aborting with System.exit(0)");
		System.exit(0);
	}
}

-------------运行结果如下：

Interrupting com.test.thread.block.SleepBlocked
Interrupt set to com.test.thread.block.SleepBlocked
Interupted Exception 
Exiting SleepBlocked.run()

======================
有些资源是无法中断的比如IO等，实例如下：

public class IOBlocked implements Runnable{

	private InputStream is;
	
	public IOBlocked(InputStream is) {
		this.is=is;
	}
	
	
	@Override
	public void run() {
		// TODO Auto-generated method stub
		System.out.println("Waiting For Read...");
		try {
			is.read();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			if(Thread.currentThread().isInterrupted()){
				System.out.println("Interrupted from blocked I/O");
			}else{
				throw new RuntimeException(e);
			}
		}
		System.out.println("Exiting IOBlocked.run()");
	}
}

=======================
上面的测试方法修改为test(new IOBlocked(System.in))，这时候的运行结果为：

Waiting For Read...
Interrupting com.test.thread.block.IOBlocked
Interrupt set to com.test.thread.block.IOBlocked
Aborting with System.exit(0)

=============================
另外synchronized也是无法中断的，示例如下:

public class SynchronizedBlocked implements Runnable{
         public synchronized void f(){
		while(true)
			Thread.yield();
	}
	
	public SynchronizedBlocked() {
		// TODO Auto-generated constructor stub
		new Thread(){
			@Override
			public void run() {
				// TODO Auto-generated method stub
				f();
			}
		}.start();
	}
	
	@Override
	public void run() {
		// TODO Auto-generated method stub
		System.out.println("Try to call f");
		f();
		System.out.println("Exting SynchronizedBlocked.run()");
	}
}

========================
将测试方法修改为test(new SynchronizedBlocked()),执行结果如下:

Try to call f
Interrupting com.test.thread.block.SynchronizedBlocked
Interrupt set to com.test.thread.block.SynchronizedBlocked
Aborting with System.exit(0)

因为这里的f()方法一直不释放锁，interrupt()方法也无法使它停止