二、Java开启异步的两种方式

骑猪看日落 2024-03-16 09:50 77阅读 0赞

##  ##

### 1、注解开启：@Async ###

#### 1.1、配置异步的线程池 ####

*  必须配置异步线程池，否则异步不会生效。
 *  @EnableAsync 注解：指定异步线程池。不指定默认使用：SimpleAsyncTaskExecutor线程池
 *  SimpleAsyncTaskExecutor是一个最简单的线程池，它没有任何的线程相关参数配置，它会为每个任务创建一个新的线程来执行，因此不建议在生产环境中使用。
 *  配置线程池见：[https://www.cnblogs.com/kakarotto-chen/p/17428432.html][https_www.cnblogs.com_kakarotto-chen_p_17428432.html]

<table> 
 <tbody> 
  <tr> 
   <td></td> 
   <td><code>package com.cc.md.config;</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>import org.springframework.context.annotation.Bean;</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>import org.springframework.context.annotation.Configuration;</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>import org.springframework.scheduling.annotation.EnableAsync;</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>import java.util.concurrent.ThreadPoolExecutor;</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>/** IO型的线程池</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>* @author CC</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>* @since 2023/5/23 0023</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>*/</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>@Configuration</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>@EnableAsync</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>public class IoThreadPool { </code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>public static final int THREAD_SIZE = 2 * (Runtime.getRuntime().availableProcessors());</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>public static final int QUEUE_SIZE = 1000;</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>@Bean(name = "myIoThreadPool")</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>public ThreadPoolTaskExecutor threadPoolExecutor(){ </code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>executor.setCorePoolSize(THREAD_SIZE);</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>executor.setMaxPoolSize(THREAD_SIZE);</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>executor.setQueueCapacity(QUEUE_SIZE);</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>executor.setRejectedExecutionHandler(new ThreadPoolExecutor.AbortPolicy());</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>executor.setKeepAliveSeconds(60);</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>executor.setAllowCoreThreadTimeOut(true);</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>executor.setAwaitTerminationSeconds(300);</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>executor.setWaitForTasksToCompleteOnShutdown(true);</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>executor.setThreadNamePrefix("myIo-Th-Pool-");</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>executor.initialize();</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>return executor;</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>}</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>}</code></td> 
  </tr> 
 </tbody> 
</table>

#### 1.2、异步方法 ####

*  异步方法必须写在另一个类中，否则不生效
 *  @Async可以打在类上、也可以打在方法上

<table> 
 <tbody> 
  <tr> 
   <td></td> 
   <td><code>1 @Async：类上，说明整个类中的方法都是异步。必须写我们自己配置的线程池 —— ("myIoThreadPool")</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>2 @Async：方法上，说明这个方法是异步。不用写我们自己配置的线程池</code></td> 
  </tr> 
 </tbody> 
</table>

*  异步接口+实现类

接口

<table> 
 <tbody> 
  <tr> 
   <td></td> 
   <td><code>package com.cc.md.service;</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>/**</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>* @author CC</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>* @since 2023/5/24 0024</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>*/</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>public interface IAsyncService { </code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>/** 异步方法1</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>* @since 2023/5/24 0024</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>* @author CC</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>**/</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>void async1();</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>/** 异步方法2</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>* @since 2023/5/24 0024</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>* @author CC</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>**/</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>void async2();</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>}</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td></td> 
  </tr> 
 </tbody> 
</table>

实现类

<table> 
 <tbody> 
  <tr> 
   <td></td> 
   <td><code>package com.cc.md.service.impl;</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>import com.cc.md.service.IAsyncService;</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>import org.slf4j.Logger;</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>import org.slf4j.LoggerFactory;</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>import org.springframework.scheduling.annotation.Async;</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>import org.springframework.stereotype.Service;</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>/** 1 @Async：类上，说明整个类中的方法都是异步。必须写我们自己配置的线程池 —— ("myIoThreadPool")</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>* 2 @Async：方法上，说明这个方法是异步。不用写我们自己配置的线程池</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>* @author CC</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>* @since 2023/5/24 0024</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>*/</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>@Service</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>@Async("myIoThreadPool")</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>public class AsyncServiceImpl implements IAsyncService { </code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>private static final Logger log = LoggerFactory.getLogger(AsyncServiceImpl.class);</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>//类上写了@Async，这里就可以不写了。</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>//可以不写 ("myIoThreadPool")。因为在IoThreadPool中开启了异步，说明异步用的就是我们配置的io线程池</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>//如果类上面打了 @Async ，这里必须写：("myIoThreadPool")</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>@Override</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>//@Async</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>public void async1(){ </code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>//模仿io流耗时</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>try { </code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>Thread.sleep(5000);</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>} catch (InterruptedException e) { </code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>throw new RuntimeException(e);</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>}</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>log.info("打印：{}", "异步方法1111！");</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>}</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>//@Async在类上面，说明这个方法也是异步方法。如果不打，无法开启异步。</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>@Override</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>public void async2(){ </code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>//模仿io流耗时</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>try { </code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>Thread.sleep(5000);</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>} catch (InterruptedException e) { </code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>throw new RuntimeException(e);</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>}</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>log.info("打印：{}", "异步方法2222！");</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>}</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>}</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td></td> 
  </tr> 
 </tbody> 
</table>

#### 1.3、测试 ####

<table> 
 <tbody> 
  <tr> 
   <td></td> 
   <td><code>@Resource</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>private IAsyncService asyncService;</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>//开启异步1 —— @Async</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>@Test</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>public void test03() throws Exception { </code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>log.info("打印：{}", "异步测试的-主方法1");</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>asyncService.async1();</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>asyncService.async2();</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>//不会等待异步方法执行，直接返回前端数据</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>log.info("打印：{}", "异步测试的-主方法2");</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>}</code></td> 
  </tr> 
 </tbody> 
</table>

结果：

![328e5007d8476b7e01dc50b4db109649.png][]

[回到顶部][Link 1]

### 2、CompletableFuture的方式 ###

使用：

<table> 
 <tbody> 
  <tr> 
   <td></td> 
   <td><code>@Resource(name = "myIoThreadPool")</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>private ThreadPoolTaskExecutor myIoThreadPool;</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>//开启异步2 —— CompletableFuture.runAsync()</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>@Test</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>public void test04() throws Exception { </code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>log.info("打印：{}", "异步测试的-主方法1");</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>CompletableFuture.runAsync(() -&gt; { </code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>log.info("打印：{}", "异步方法1！");</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>//异步执行的代码，也可以是方法，该方法不用单独写到其他类中。</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>this.async2("异步方法1！-end");</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>}, myIoThreadPool);</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>//不会等待异步方法执行，直接返回前端数据</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>log.info("打印：{}", "异步测试的-主方法2");</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>}</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>//异步需要执行的方法，可以写在同一个类中。</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>private void async2(String msg) { </code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>//模仿io流耗时</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>try { </code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>Thread.sleep(5000);</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>} catch (InterruptedException e) { </code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>throw new RuntimeException(e);</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>}</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>log.info("打印：{}", msg);</code></td> 
  </tr> 
  <tr> 
   <td></td> 
   <td><code>}</code></td> 
  </tr> 
 </tbody> 
</table>

结果：

![5cf3a81e46d67b96c177e43cdbf6e1fc.png][]

*  后续CompletableFuture的使用见：《Java的CompletableFuture，Java的多线程开发》

[https_www.cnblogs.com_kakarotto-chen_p_17428432.html]: https://www.cnblogs.com/kakarotto-chen/p/17428432.html
[328e5007d8476b7e01dc50b4db109649.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/16/9244f8691f3a43baab53f571318ba099.png
[Link 1]: https://www.cnblogs.com/kakarotto-chen/p/17428619.html#_labelTop
[5cf3a81e46d67b96c177e43cdbf6e1fc.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/16/982abf4498ba43f5b656df7b27936ff5.png