java并发编程- 7 - 线程池这一章我们已经提到过Future，用于接收子线程的返回值。再来回顾一下代码：
@Test
public void futureTest() throws ExecutionException, InterruptedException {
// 创建 FutureTask
FutureTask<User> futureTask = new FutureTask<User>(()-> {
return new User(2222,1000);
});
// 创建线程池
ThreadPoolExecutor es=new ThreadPoolExecutor(20,50,3, TimeUnit.SECONDS,
new ArrayBlockingQueue<>(200),new ThreadPoolExecutor.DiscardOldestPolicy());
// 提交 FutureTask
es.submit(futureTask);
// 获取计算结果
User result = futureTask.get();
log.info("result:"+result);
}
这个列子稍微有些简单，我们还是回到组装车子的场景：1、制造车身。2、制造轮子。3、制造车子。
(省略entity)代码如下：
@Test
public void madeCarUseFuture() throws ExecutionException, InterruptedException {
//制造body
FutureTask<CarBody> carBodyFutureTask=new FutureTask<CarBody>(new Callable<CarBody>() {
@Override
public CarBody call() throws Exception {
log.info("madde body start");
CarBody body=new CarBody("my carbody");
Thread.sleep(2000);
log.info("madde body success");
return body;
}
});
//制造轮子
FutureTask<CarWheel> carWheelFutureTask=new FutureTask<CarWheel>(()->{
log.info("made wheel start");
CarWheel wheel=new CarWheel("my carWheel");
Thread.sleep(2000);
log.info("made wheel success");
return wheel;
});
carBodyFutureTask.run();
carWheelFutureTask.run();
CarBody carBody=carBodyFutureTask.get();
CarWheel wheel=carWheelFutureTask.get();
//制造车子
Car car=new Car(carBody,wheel);
//从结果看出来，是同步执行的
log.info(car.toString());
}
@Test
public void madeCarUseFuturePool() throws ExecutionException, InterruptedException {
ThreadPoolExecutor executor=new ThreadPoolExecutor(20,50,3, TimeUnit.SECONDS,
new ArrayBlockingQueue<>(200),new ThreadPoolExecutor.DiscardOldestPolicy());
//制造body
FutureTask<CarBody> carBodyFutureTask=new FutureTask<CarBody>(new Callable<CarBody>() {
@Override
public CarBody call() throws Exception {
log.info("madde body start");
CarBody body=new CarBody("my carbody");
Thread.sleep(2000);
log.info("madde body success");
return body;
}
});
//制造轮子
FutureTask<CarWheel> carWheelFutureTask=new FutureTask<CarWheel>(()->{
log.info("made wheel start");
CarWheel wheel=new CarWheel("my carWheel");
Thread.sleep(2000);
log.info("made wheel success");
return wheel;
});
executor.submit(carBodyFutureTask);
executor.submit(carWheelFutureTask);
CarBody carBody=carBodyFutureTask.get();
CarWheel wheel=carWheelFutureTask.get();
//制造车子
Car car=new Car(carBody,wheel);
//从结果看出来，是异步执行的
log.info(car.toString());
}
