JUC包(六) Executor框架

你的名字 2022-02-27 06:30 253阅读 0赞

### 前言 ###

在上文中, 我们介绍了线程池的基本构造与使用原理. 本章, 我们将介绍下线程池的上一层的包装`Executor`.

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### 正文 ###

基本框架图:  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly95YW54bWwuYmxvZy5jc2RuLm5ldA_size_16_color_FFFFFF_t_70]  
线程池运行图:  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly95YW54bWwuYmxvZy5jc2RuLm5ldA_size_16_color_FFFFFF_t_70 1]

为了应对不同的场景, `Java`设计者设计出不同的线程池

> ThreadPoolExecutor

*  FixedThreadPool 固定大小线程池
 *  SingleThreadPool 单线程线程池
 *  CachedThreadPool 带缓存线程池(大小无界)

> ScheduledExecutorExecutor

*  ScheduledExecutorPoolExecutor
 *  SingleThreadScheduleExecutor

> Future接口  
> 通过`submit`提交的任务,将会返回一个实现`Future`接口的对象.(JDK 1.7 FutureTask)  
> Runnable与Callable接口  
> 区别在于:
> 
> 1.  `Runnable` 调用的方法为`run()`;`Callable`调用的方法为`call()`;
> 2.  `Runnable` 无返回值, `Callable`可以通过调用`FutureTask.get()`方法获取返回值;
> 3.  `Runnable`异常内部处理, `Callable`可以抛出.  
>     注意: `FutureTask.get()`调用时,会阻塞当前线程.直到获取到返回值.

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### 基本使用 ###

import java.util.concurrent.Executor;
    import java.util.concurrent.ExecutorService;
    import java.util.concurrent.Executors;
    
    public class ExecutorTest {
    	public static void main(String[] args) throws InterruptedException {
    		ExecutorService service = Executors.newFixedThreadPool(4);
    		service.submit(new Runnable(){
    
    			@Override
    			public void run() {
    				while(true){
    					System.out.println(Thread.currentThread().getName()+":"+System.currentTimeMillis());
    				}
    			}
    			
    		});
    		Thread.sleep(10000);
    		service.shutdown();
    		
    		
    		ExecutorService singleExecutorService = Executors.newSingleThreadExecutor();
    		ExecutorService cacheExecutorService = Executors.newCachedThreadPool();
    		ExecutorService scheduleExecutorService = Executors.newScheduledThreadPool(4);
    
    		
    	}
    }

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### Others ###

`Executor`与`Executors` `ExecutorService`的区别?

> 一个是接口,一个是静态类.  
> Executor 接口对象能执行我们的线程任务；  
> Executors 工具类的不同方法按照我们的需求创建了不同的线程池，来满足业务的需求。  
> ExecutorService 接口继承了Executor接口并进行了扩展，提供了更多的方法，我们能够获得任务执行的状态并且可以获取任务的返回值。  
> [Executor和Executors的区别][Executor_Executors]  
> [java.util.concurrent 包中Executor与Executors的区别][java.util.concurrent _Executor_Executors]  
> [Executor, ExecutorService 和 Executors 间的不同][Executor_ ExecutorService _ Executors]

--------------------

### Reference ###

\[1\] [Java线程(一):线程结构图及状态][Java]  
\[2\] [ThreadPoolExecutor使用详解][ThreadPoolExecutor]  
\[3\] [Runnable和Callable的区别和用法][Runnable_Callable]  
\[4\] [Java Callable接口和Runnable接口的区别][Java Callable_Runnable]  
\[5\] [Java并发——Executor框架详解（Executor框架结构与框架成员）][Java_Executor_Executor]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly95YW54bWwuYmxvZy5jc2RuLm5ldA_size_16_color_FFFFFF_t_70]: /images/20220227/050ffe346c284f79a21873b17156b943.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly95YW54bWwuYmxvZy5jc2RuLm5ldA_size_16_color_FFFFFF_t_70 1]: /images/20220227/b8b59818c8114f13aca93b1a390eef31.png
[Executor_Executors]: https://www.cnblogs.com/hujinshui/p/10367876.html
[java.util.concurrent _Executor_Executors]: https://blog.csdn.net/qq991029781/article/details/52798249
[Executor_ ExecutorService _ Executors]: https://blog.csdn.net/feelinghappy/article/details/77021748
[Java]: https://blog.csdn.net/a355586533/article/details/78416334
[ThreadPoolExecutor]: https://www.cnblogs.com/zedosu/p/6665306.html
[Runnable_Callable]: https://blog.csdn.net/Liu_yunzhao/article/details/78504287
[Java Callable_Runnable]: https://blog.csdn.net/Q_AN1314/article/details/52468581
[Java_Executor_Executor]: https://blog.csdn.net/tongdanping/article/details/79604637