前言

之前我们使用多线程要么是继承Thread类，要么是实现Runnable接口，然后重写一下run()方法即可。
但是只有的话如果有死锁、对共享资源的访问和随时监控线程状态就不行了，于是在Java5之后就有了Callable接口。

简单的实现有返回值的线程

代码如下：
CallableFuture类

package com.test.thread;

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

public class CallableFuture {
	public static void main(String[] args) {
		
		//创建一个线程池
		ExecutorService pool = Executors.newFixedThreadPool(3) ;
		
		//创建三个有返回值的任务
		CallableTest callableTest1 = new CallableTest("我是线程1") ;
		CallableTest callableTest2 = new CallableTest("我是线程2") ;
		CallableTest callableTest3 = new CallableTest("我是线程3") ;
		
		Future future1 = pool.submit(callableTest1) ;
		Future future2 = pool.submit(callableTest2) ;
		Future future3 = pool.submit(callableTest3) ;
		
		try {
			System.out.println(future1.get().toString());
			System.out.println(future2.get().toString());
			System.out.println(future3.get().toString());
		} catch (InterruptedException e) {
			e.printStackTrace();
		} catch (ExecutionException e) {
			e.printStackTrace();
		}finally{
			pool.shutdown();
		}
		
	}
}

CallableTest·类：

package com.test.thread;


import java.util.concurrent.Callable;

public class CallableTest implements Callable {
	
	private String threadName ;
	
	public CallableTest(String threadName) {
		this.threadName = threadName;
	}
	@Override
	public Object call() throws Exception {
		return threadName+"返回的信息";
	}
	
	
}

运行结果：

总结

以上就是一个简单的例子，需要了解更多详情可以去看那几个类的API。