java的Future使用方法

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，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。也就是说，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