我们常用ThreadPoolExecutor提供的线程池服务，springboot框架提供了@Async注解，帮助我们更方便的将业务逻辑提交到线程池中异步执行。
话不多说，编码开始：
1.创建springboot工程
创建一个springboot的web工程threadpooldemoserver，pom.xml内容如下：
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.fengyuduke.boot</groupId> <artifactId>threadpooldemoserver</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>threadpooldemoserver</name> <url>http://maven.apache.org</url> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.5.9.RELEASE</version> <relativePath/> <!-- lookup parent from repository --> </parent> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding> <java.version>1.8</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-devtools</artifactId> <optional>true</optional> <!-- 这个需要为 true 热部署才有效 --> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project>
2.创建Service层的接口和实现
创建一个service层的接口AsyncService，如下：
public interface AsyncService { /** * 执行异步任务 */ void executeAsync(); }
对应的AsyncServiceImpl，实现如下：
@Service public class AsyncServiceImpl implements AsyncService { private static final Logger logger = LoggerFactory.getLogger(AsyncServiceImpl.class); @Overridepublic void executeAsync() { logger.info("start executeAsync"); try{ Thread.sleep(1000); }catch(Exception e){ e.printStackTrace(); } logger.info("end executeAsync"); } }
这个方法做的事情很简单：sleep了一秒钟；
3.创建controller
创建一个controller为Hello，里面定义一个http接口，做的事情是调用Service层的服务，如下：
@RestController public class Hello { private static final Logger logger = LoggerFactory.getLogger(Hello.class); @Autowired private AsyncService asyncService; @RequestMapping("/") public String submit(){ logger.info("start submit"); //调用service层的任务 asyncService.executeAsync(); logger.info("end submit"); return "success"; } }
至此，我们已经做好了一个http请求的服务，里面做的事情其实是同步的，接下来我们就开始配置springboot的线程池服务，将service层做的事情都提交到线程池中去处理；
4.springboot的线程池配置
创建一个配置类ExecutorConfig，用来定义如何创建一个ThreadPoolTaskExecutor，要使用@Configuration和@EnableAsync这两个注解，表示这是个配置类，并且是线程池的配置类，如下所示：
@Configuration @EnableAsync public class ExecutorConfig { private static final Logger logger = LoggerFactory.getLogger(ExecutorConfig.class); @Bean public Executor asyncServiceExecutor() { logger.info("start asyncServiceExecutor"); ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor(); //配置核心线程数 executor.setCorePoolSize(5); //配置最大线程数 executor.setMaxPoolSize(5); //配置队列大小 executor.setQueueCapacity(99999); //配置线程池中的线程的名称前缀 executor.setThreadNamePrefix("async-service-"); // rejection-policy：当pool已经达到max size的时候，如何处理新任务 // CALLER_RUNS：不在新线程中执行任务，而是有调用者所在的线程来执行 executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy()); //执行初始化 executor.initialize(); return executor; } }
注意，上面的方法名称为asyncServiceExecutor，稍后马上用到；
5.将Service层的服务异步化
打开AsyncServiceImpl.java，在executeAsync方法上增加注解@Async(“asyncServiceExecutor”)，asyncServiceExecutor是前面ExecutorConfig.java中的方法名，表明executeAsync方法进入的线程池是asyncServiceExecutor方法创建的，如下：
@Override @Async("asyncServiceExecutor") public void executeAsync() { logger.info("start executeAsync"); try{ Thread.sleep(1000); }catch(Exception e){ e.printStackTrace(); } logger.info("end executeAsync"); }
验证效果
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将这个springboot运行起来（pom.xml所在文件夹下执行mvn spring-boot:run）；
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在浏览器输入：http://localhost:8080；
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在浏览器用F5按钮快速多刷新几次；
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在springboot的控制台看见日志如下：
2019-06-13 16:41:01.026 INFO 12652 --- [nio-8080-exec-1] com.fengyuduke.boot.controller.Hello : start submit 2019-06-13 16:41:01.027 INFO 12652 --- [nio-8080-exec-1] com.fengyuduke.boot.controller.Hello : end submit 2019-06-13 16:41:01.027 INFO 12652 --- [async-service-1] c.f.boot.serviceimpl.AsyncServiceImpl : start executeAsync 2019-06-13 16:41:01.174 INFO 12652 --- [nio-8080-exec-3] com.fengyuduke.boot.controller.Hello : start submit 2019-06-13 16:41:01.174 INFO 12652 --- [nio-8080-exec-3] com.fengyuduke.boot.controller.Hello : end submit 2019-06-13 16:41:01.174 INFO 12652 --- [async-service-2] c.f.boot.serviceimpl.AsyncServiceImpl : start executeAsync 2019-06-13 16:41:01.320 INFO 12652 --- [nio-8080-exec-5] com.fengyuduke.boot.controller.Hello : start submit 2019-06-13 16:41:01.320 INFO 12652 --- [nio-8080-exec-5] com.fengyuduke.boot.controller.Hello : end submit 2019-06-13 16:41:01.320 INFO 12652 --- [async-service-3] c.f.boot.serviceimpl.AsyncServiceImpl : start executeAsync 2019-06-13 16:41:01.583 INFO 12652 --- [nio-8080-exec-7] com.fengyuduke.boot.controller.Hello : start submit 2019-06-13 16:41:01.583 INFO 12652 --- [nio-8080-exec-7] com.fengyuduke.boot.controller.Hello : end submit 2019-06-13 16:41:01.583 INFO 12652 --- [async-service-4] c.f.boot.serviceimpl.AsyncServiceImpl : start executeAsync 2019-06-13 16:41:02.027 INFO 12652 --- [async-service-1] c.f.boot.serviceimpl.AsyncServiceImpl : end executeAsync 2019-06-13 16:41:02.174 INFO 12652 --- [async-service-2] c.f.boot.serviceimpl.AsyncServiceImpl : end executeAsync 2019-06-13 16:41:02.343 INFO 12652 --- [async-service-3] c.f.boot.serviceimpl.AsyncServiceImpl : end executeAsync 2019-06-13 16:41:02.583 INFO 12652 --- [async-service-4] c.f.boot.serviceimpl.AsyncServiceImpl : end executeAsync
如上日志所示，我们可以看到controller的执行线程是"nio-8080-exec-*"，这是tomcat的执行线程，而service层的日志显示线程名为“async-service-*”，显然已经在我们配置的线程池中执行了，并且每次请求中，controller的起始和结束日志都是连续打印的，表明每次请求都快速响应了，而耗时的操作都留给线程池中的线程去异步执行；
扩展ThreadPoolTaskExecutor
虽然我们已经用上了线程池，但是还不清楚线程池当时的情况，有多少线程在执行，多少在队列中等待呢？这里我创建了一个ThreadPoolTaskExecutor的子类，在每次提交线程的时候都会将当前线程池的运行状况打印出来，代码如下：
public class VisiableThreadPoolTaskExecutor extends ThreadPoolTaskExecutor { private static final Logger logger = LoggerFactory.getLogger(VisiableThreadPoolTaskExecutor.class); private void showThreadPoolInfo(String prefix){ ThreadPoolExecutor threadPoolExecutor = getThreadPoolExecutor(); if(null==threadPoolExecutor){ return; } logger.info("{}, {},taskCount [{}], completedTaskCount [{}], activeCount [{}], queueSize [{}]", this.getThreadNamePrefix(), prefix, threadPoolExecutor.getTaskCount(), threadPoolExecutor.getCompletedTaskCount(), threadPoolExecutor.getActiveCount(), threadPoolExecutor.getQueue().size()); } @Override public void execute(Runnable task) { showThreadPoolInfo("1. do execute"); super.execute(task); } @Override public void execute(Runnable task, long startTimeout) { showThreadPoolInfo("2. do execute"); super.execute(task, startTimeout); } @Override public Future<?> submit(Runnable task) { showThreadPoolInfo("1. do submit"); return super.submit(task); } @Override public <T> Future<T> submit(Callable<T> task) { showThreadPoolInfo("2. do submit"); return super.submit(task); } @Override public ListenableFuture<?> submitListenable(Runnable task) { showThreadPoolInfo("1. do submitListenable"); return super.submitListenable(task); } @Override public <T> ListenableFuture<T> submitListenable(Callable<T> task) { showThreadPoolInfo("2. do submitListenable"); return super.submitListenable(task); } }
如上所示，showThreadPoolInfo方法中将任务总数、已完成数、活跃线程数，队列大小都打印出来了，然后Override了父类的execute、submit等方法，在里面调用showThreadPoolInfo方法，这样每次有任务被提交到线程池的时候，都会将当前线程池的基本情况打印到日志中；
修改ExecutorConfig.java的asyncServiceExecutor方法，将ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor()改为ThreadPoolTaskExecutor executor = new VisiableThreadPoolTaskExecutor()，如下所示：
@Configuration @EnableAsync public class ExecutorConfig { private static final Logger logger = LoggerFactory.getLogger(ExecutorConfig.class); @Bean public Executor asyncServiceExecutor() { logger.info("start asyncServiceExecutor"); // ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor(); ThreadPoolTaskExecutor executor = new VisiableThreadPoolTaskExecutor(); //配置核心线程数 executor.setCorePoolSize(5); //配置最大线程数 executor.setMaxPoolSize(5); //配置队列大小 executor.setQueueCapacity(99999); //配置线程池中的线程的名称前缀 executor.setThreadNamePrefix("async-service-"); // rejection-policy：当pool已经达到max size的时候，如何处理新任务 // CALLER_RUNS：不在新线程中执行任务，而是有调用者所在的线程来执行 executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy()); //执行初始化 executor.initialize(); return executor; } }
再次启动该工程，再浏览器反复刷新http://localhost:8080，看到的日志如下：
2019-06-13 16:46:56.490 INFO 12860 --- [io-8080-exec-10] com.fengyuduke.boot.controller.Hello : start submit 2019-06-13 16:46:56.491 INFO 12860 --- [io-8080-exec-10] c.f.b.c.VisiableThreadPoolTaskExecutor : async-service-, 2. do submit,taskCount [4], completedTaskCount [4], activeCount [0], queueSize [0] 2019-06-13 16:46:56.491 INFO 12860 --- [io-8080-exec-10] com.fengyuduke.boot.controller.Hello : end submit 2019-06-13 16:46:56.491 INFO 12860 --- [async-service-5] c.f.boot.serviceimpl.AsyncServiceImpl : start executeAsync 2019-06-13 16:46:56.793 INFO 12860 --- [nio-8080-exec-2] com.fengyuduke.boot.controller.Hello : start submit 2019-06-13 16:46:56.793 INFO 12860 --- [nio-8080-exec-2] c.f.b.c.VisiableThreadPoolTaskExecutor : async-service-, 2. do submit,taskCount [5], completedTaskCount [4], activeCount [1], queueSize [0] 2019-06-13 16:46:56.793 INFO 12860 --- [nio-8080-exec-2] com.fengyuduke.boot.controller.Hello : end submit 2019-06-13 16:46:56.794 INFO 12860 --- [async-service-1] c.f.boot.serviceimpl.AsyncServiceImpl : start executeAsync 2019-06-13 16:46:56.935 INFO 12860 --- [nio-8080-exec-4] com.fengyuduke.boot.controller.Hello : start submit 2019-06-13 16:46:56.935 INFO 12860 --- [nio-8080-exec-4] c.f.b.c.VisiableThreadPoolTaskExecutor : async-service-, 2. do submit,taskCount [6], completedTaskCount [4], activeCount [2], queueSize [0] 2019-06-13 16:46:56.935 INFO 12860 --- [nio-8080-exec-4] com.fengyuduke.boot.controller.Hello : end submit 2019-06-13 16:46:56.935 INFO 12860 --- [async-service-2] c.f.boot.serviceimpl.AsyncServiceImpl : start executeAsync 2019-06-13 16:46:57.072 INFO 12860 --- [nio-8080-exec-6] com.fengyuduke.boot.controller.Hello : start submit 2019-06-13 16:46:57.073 INFO 12860 --- [nio-8080-exec-6] c.f.b.c.VisiableThreadPoolTaskExecutor : async-service-, 2. do submit,taskCount [7], completedTaskCount [4], activeCount [3], queueSize [0] 2019-06-13 16:46:57.073 INFO 12860 --- [nio-8080-exec-6] com.fengyuduke.boot.controller.Hello : end submit 2019-06-13 16:46:57.073 INFO 12860 --- [async-service-3] c.f.boot.serviceimpl.AsyncServiceImpl : start executeAsync 2019-06-13 16:46:57.215 INFO 12860 --- [nio-8080-exec-8] com.fengyuduke.boot.controller.Hello : start submit 2019-06-13 16:46:57.216 INFO 12860 --- [nio-8080-exec-8] c.f.b.c.VisiableThreadPoolTaskExecutor : async-service-, 2. do submit,taskCount [8], completedTaskCount [4], activeCount [4], queueSize [0] 2019-06-13 16:46:57.216 INFO 12860 --- [nio-8080-exec-8] com.fengyuduke.boot.controller.Hello : end submit 2019-06-13 16:46:57.216 INFO 12860 --- [async-service-4] c.f.boot.serviceimpl.AsyncServiceImpl : start executeAsync 2019-06-13 16:46:57.345 INFO 12860 --- [io-8080-exec-10] com.fengyuduke.boot.controller.Hello : start submit 2019-06-13 16:46:57.345 INFO 12860 --- [io-8080-exec-10] c.f.b.c.VisiableThreadPoolTaskExecutor : async-service-, 2. do submit,taskCount [9], completedTaskCount [4], activeCount [5], queueSize [0] 2019-06-13 16:46:57.345 INFO 12860 --- [io-8080-exec-10] com.fengyuduke.boot.controller.Hello : end submit 2019-06-13 16:46:57.491 INFO 12860 --- [async-service-5] c.f.boot.serviceimpl.AsyncServiceImpl : end executeAsync 2019-06-13 16:46:57.491 INFO 12860 --- [async-service-5] c.f.boot.serviceimpl.AsyncServiceImpl : start executeAsync 2019-06-13 16:46:57.795 INFO 12860 --- [async-service-1] c.f.boot.serviceimpl.AsyncServiceImpl : end executeAsync 2019-06-13 16:46:57.936 INFO 12860 --- [async-service-2] c.f.boot.serviceimpl.AsyncServiceImpl : end executeAsync 2019-06-13 16:46:58.074 INFO 12860 --- [async-service-3] c.f.boot.serviceimpl.AsyncServiceImpl : end executeAsync 2019-06-13 16:46:58.222 INFO 12860 --- [async-service-4] c.f.boot.serviceimpl.AsyncServiceImpl : end executeAsync 2019-06-13 16:46:58.492 INFO 12860 --- [async-service-5] c.f.boot.serviceimpl.AsyncServiceImpl : end executeAsync
注意这一行日志：
2. do submit,taskCount [9], completedTaskCount [4], activeCount [5], queueSize [0]
这说明提交任务到线程池的时候，调用的是submit(Callable task)这个方法，当前已经提交了9个任务，完成了4个，当前有5个线程在处理任务，还剩0个任务在队列中等待，线程池的基本情况一路了然；
至此，springboot线程池服务的实战就完成了，希望能帮您在工程中快速实现异步服务。
代码下载地址：https://gitee.com/fengyuduke/my_open_resources/blob/master/threadpooldemoserver.zip