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。



简单实现带返回值的线程

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();
}

}
}

代码如下: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


我是线程1返回的信息
我是线程2返回的信息
我是线程3返回的信息