public interface Executor {

  void execute(Runnable command);
}

public interface ExecutorService extends Executor {

  List<Runnable> shutdownNow();


  boolean isTerminated();


  <T> Future<T> submit(Callable<T> task);

 }

ExecutorService threadPool = Executors.newSingleThreadExecutor();

public static ExecutorService newSingleThreadExecutor() {
    return new FinalizableDelegatedExecutorService
      (new ThreadPoolExecutor(1, 1,
                  0L, TimeUnit.MILLISECONDS,
                  new LinkedBlockingQueue<Runnable>()));
  }

ExecutorService threadPool = Executors.newFixedThreadPool(5);

public static ExecutorService newFixedThreadPool(int nThreads) {
    return new ThreadPoolExecutor(nThreads, nThreads,
                   0L, TimeUnit.MILLISECONDS,
                   new LinkedBlockingQueue<Runnable>());
  }

ExecutorService threadPool = Executors.newCachedThreadPool();

public static ExecutorService newCachedThreadPool() {
    return new ThreadPoolExecutor(0, Integer.MAX_VALUE,
                   60L, TimeUnit.SECONDS,
                   new SynchronousQueue<Runnable>());
  }

public interface Future<V> {
 
   boolean cancel(boolean mayInterruptIfRunning);
 
   boolean isCancelled();
 
   boolean isDone();
 
   V get() throws InterruptedException, ExecutionException;
 
   V get(long timeout, TimeUnit unit)
     throws InterruptedException, ExecutionException, TimeoutException;
 }

public class FutureTask<V> implements RunnableFuture<V>

public interface RunnableFuture<V> extends Runnable, Future<V>

public class MyCallableTask implements Callable<Integer>
 {
   @Override
   public Integer call()
     throws Exception
   {
     System.out.println("callable do somothing");
     Thread.sleep(5000);
     return new Random().nextInt(100);
   }
 }

public class CallableTest
 {
   public static void main(String[] args) throws Exception
   {
     Callable<Integer> callable = new MyCallableTask();
     FutureTask<Integer> future = new FutureTask<Integer>(callable);
     Thread thread = new Thread(future);
     thread.start();
     Thread.sleep(100);
     //尝试取消对此任务的执行
     future.cancel(true);
     //判断是否在任务正常完成前取消
     System.out.println("future is cancel:" + future.isCancelled());
     if(!future.isCancelled())
     {
       System.out.println("future is cancelled");
     }
     //判断任务是否已完成
     System.out.println("future is done:" + future.isDone());
     if(!future.isDone())
     {
       System.out.println("future get=" + future.get());
     }
     else
     {
       //任务已完成
       System.out.println("task is done");
     }
   }
 }

callable do somothing
future is cancel:true
future is done:true
task is done

future.cancel(true);

System.out.println("future is cancel:" + future.isCancelled());

 System.out.println("future is done:" + future.isDone());

System.out.println("future get=" + future.get());

public class CallableThread implements Callable<String>
{
  @Override
  public String call()
    throws Exception
  {
    System.out.println("进入Call方法，开始休眠，休眠时间为：" + System.currentTimeMillis());
    Thread.sleep(10000);
    return "今天停电";
  }

  public static void main(String[] args) throws Exception
  {
    ExecutorService es = Executors.newSingleThreadExecutor();
    Callable<String> call = new CallableThread();
    Future<String> fu = es.submit(call);
    es.shutdown();
    Thread.sleep(5000);
    System.out.println("主线程休眠5秒，当前时间" + System.currentTimeMillis());
    String str = fu.get();
    System.out.println("Future已拿到数据，str=" + str + ";当前时间为：" + System.currentTimeMillis());
  }
}

进入Call方法，开始休眠，休眠时间为：1478606602676
主线程休眠5秒，当前时间1478606608676
Future已拿到数据，str=今天停电;当前时间为：1478606612677

public static void main(String[] args) throws Exception
  {
   ExecutorService es = Executors.newSingleThreadExecutor();
   Callable<String> call = new CallableThread();
   FutureTask<String> task = new FutureTask<String>(call);
   es.submit(task);
   es.shutdown();
   Thread.sleep(5000);
   System.out.println("主线程等待5秒，当前时间为：" + System.currentTimeMillis());
   String str = task.get();
   System.out.println("Future已拿到数据，str=" + str + ";当前时间为：" + System.currentTimeMillis());
  }