java的Future用法

首先，Future是一个接口，该接口用来返回异步的结果。

package com.itbuluoge.mythread;

import java.util.ArrayList;
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;
import java.util.concurrent.TimeUnit;

class TaskWithResult implements Callable<String>
{

  public String call() throws Exception {
    // TODO Auto-generated method stub
    Thread.sleep(1000);
    return "OK";
  }
  
}
public class CallableDemo {

  /**
   * @param args
   * @throws Exception 
   * @throws InterruptedException 
   */
  public static void main(String[] args) throws InterruptedException, Exception {
    // TODO Auto-generated method stub
    ExecutorService exec=Executors.newCachedThreadPool();
    Future<String> st=exec.submit(new TaskWithResult());
    
    /*同步结果，并且设置超时时间*/
    System.out.println(st.get(10000, TimeUnit.MILLISECONDS));
    System.out.println("over");
    
    
  }

}

其中st.get(10000, TimeUnit.MILLISECONDS)是同步阻塞的，也就是说，会一直等待st的返回结果，在结果返回后，才会继续执行下去。

输出结果