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，而且设置超时时间*/
System.out.println(st.get(10000， TimeUnit.MILLISECONDS));
System.out.println("over");
}
}
　　当中st.get(10000， TimeUnit.MILLISECONDS)是同步堵塞的。也是说，会一直等待st的返回结果，在结果返回后。才会继续运行下去。
　　输出结果