java的Future使用方法

首先，Future是一個接口，該接口用來返回異步的結果。

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());
		
		/*同步結果，而且設置超時時間*/
		System.out.println(st.get(10000, TimeUnit.MILLISECONDS));
		System.out.println("over");
		
		
	}

}

當中st.get(10000, TimeUnit.MILLISECONDS)是同步堵塞的。也就是說，會一直等待st的返回結果，在結果返回后。才會繼續運行下去。

輸出結果