JAVA线程池原理详解（2）

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);
    }
}

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());
    }