Java thread中的callback和Future的简单使用

package threadPa;


import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;


/** 
 * @author ltz: 
 * @version 上午11:43:37 
 * 类说明 
 */
public class ThreadCallTest {
  public static void main(String[]args){
  ExecutorService exe=Executors.newCachedThreadPool();
  Task task=new Task();
  
  Future result=exe.submit(task);
  exe.shutdown();
  
  try {
System.out.println("call result"+result.get());
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
  System.out.println("over");
  
  }
}


class Task implements Callable{


@Override
public Integer call() throws Exception {
System.out.println("begin ....");
Thread.sleep(3000);
return 100;
}

}

　我们先来看一下FutureTask的实现：

public  class  FutureTask  implements  RunnableFuture

 　　FutureTask类实现了RunnableFuture接口，我们看一下RunnableFuture接口的实现：

public  interface  RunnableFuture  extends  Runnable, Future {
    void  run();
}

 　　可以看出RunnableFuture继承了Runnable接口和Future接口，而FutureTask实现了RunnableFuture接口。所以它既可以作为Runnable被线程执行，又可以作为Future得到Callable的返回值。

　　FutureTask提供了2个构造器：

public  FutureTask(Callable callable) {
}
public  FutureTask(Runnable runnable, V result) {
}

　　事实上，FutureTask是Future接口的一个唯一实现类。