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建议先看我另外一篇文章：

开发环境

• SpringBoot 2.1.10.RELEASE
• JDK 1.8

1：启动类添加@EnableAsync注解

package com.nobody;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.scheduling.annotation.EnableAsync;@SpringBootApplication@EnableAsyncpublic class Application {
   	public static void main(String[] args) {
   		SpringApplication.run(Application.class, args);	}}

2：线程池配置

package com.nobody.config;import java.util.concurrent.Executor;import java.util.concurrent.ThreadPoolExecutor;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;@Configurationpublic class ExecutorConfig {
       public static final int CORE_POOL_SIZE = 5;    public static final int MAX_POOL_SIZE = 10;    public static final int QUEUE_CAPACITY = 100;    @Bean("myExecutor")    public Executor asyncServiceExecutor() {
           ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();        // 核心线程数大小        executor.setCorePoolSize(CORE_POOL_SIZE);        // 最大线程数大小        executor.setMaxPoolSize(MAX_POOL_SIZE);        // 阻塞队列容量        executor.setQueueCapacity(QUEUE_CAPACITY);        // 线程名前缀        executor.setThreadNamePrefix("myTask-");        // rejectionPolicy：当queue达到maxSize并且此时maxPoolSize也达到最大值的时候，对于新任务的处理策略        // CallerRunsPolicy：不在新线程中执行任务，而是交由调用者所在的线程来执行        executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());        executor.initialize();        return executor;    }}

3：编写异步方法

package com.nobody.domain;import java.util.Map;import java.util.concurrent.CountDownLatch;import java.util.concurrent.Future;import java.util.concurrent.TimeUnit;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.slf4j.MDC;import org.springframework.scheduling.annotation.Async;import org.springframework.scheduling.annotation.AsyncResult;import org.springframework.stereotype.Service;@Servicepublic class AsyncService {
       private static final Logger LOGGER = LoggerFactory.getLogger(AsyncService.class);    // 简单版本    @Async    public void asyncTaskA() {
           LOGGER.info("asyncTaskA 异步方法执行.");    }    // 入参类型，此处将调用者(线程)的MDC信息传入，主要是保持日志输出时，两个线程有同样的traceId    @Async    public void asyncTaslB(Map
   
     contextMap) {
           MDC.setContextMap(contextMap);        LOGGER.info("asyncTaskB 异步方法执行.");    }    // 线程执行后计数器减1    @Async    public void asyncTaskC(CountDownLatch cdl) {
           LOGGER.info("asyncTaskC 异步方法执行.");        try {
               TimeUnit.SECONDS.sleep(2);        } catch (InterruptedException e) {
               e.printStackTrace();        }        cdl.countDown();    }    // 有返回参数类型    @Async    public Future
    
      asyncTaskD(String message) {
           LOGGER.info("asyncTaskD 异步方法执行.");        return new AsyncResult
     
      ("@" + message);    }}
     
    
   

4：异步调用

package com.nobody.controller;import java.util.concurrent.ExecutionException;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.bind.annotation.GetMapping;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;import com.nobody.domain.AsyncService;@RestController@RequestMapping("demo")public class DemoController {
       private static final Logger LOGGER = LoggerFactory.getLogger(DemoController.class);    @Autowired    private AsyncService asyncService;    @GetMapping("test")    public void test() throws InterruptedException, ExecutionException {
           asyncService.asyncTaskA();        LOGGER.info("主线程执行...");    }}

输出结果：

package com.nobody.controller;import java.util.UUID;import java.util.concurrent.ExecutionException;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.slf4j.MDC;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.bind.annotation.GetMapping;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;import com.nobody.domain.AsyncService;@RestController@RequestMapping("demo")public class DemoController {
       private static final Logger LOGGER = LoggerFactory.getLogger(DemoController.class);    @Autowired    private AsyncService asyncService;    @GetMapping("test")    public void test() throws InterruptedException, ExecutionException {
           MDC.put("traceId", UUID.randomUUID().toString().replaceFirst("-", ""));        asyncService.asyncTaskB(MDC.getCopyOfContextMap());        LOGGER.info("主线程执行...");    }}

输出结果：

package com.nobody.controller;import java.util.concurrent.CountDownLatch;import java.util.concurrent.ExecutionException;import java.util.concurrent.TimeUnit;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.bind.annotation.GetMapping;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;import com.nobody.domain.AsyncService;@RestController@RequestMapping("demo")public class DemoController {
       private static final Logger LOGGER = LoggerFactory.getLogger(DemoController.class);    @Autowired    private AsyncService asyncService;    @GetMapping("test")    public void test() throws InterruptedException, ExecutionException {
           CountDownLatch cdl = new CountDownLatch(2);        asyncService.asyncTaskC(cdl);        asyncService.asyncTaskC(cdl);        try {
               // 等等两个线程执行后，再继续下面的执行，如果超过5s则不等待            cdl.await(5, TimeUnit.SECONDS);        } catch (InterruptedException e) {
               e.printStackTrace();        }        LOGGER.info("主线程执行...");    }}

输出结果：

package com.nobody.controller;import java.util.concurrent.ExecutionException;import java.util.concurrent.Future;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.bind.annotation.GetMapping;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;import com.nobody.domain.AsyncService;@RestController@RequestMapping("demo")public class DemoController {
       private static final Logger LOGGER = LoggerFactory.getLogger(DemoController.class);    @Autowired    private AsyncService asyncService;    @GetMapping("test")    public void test() throws InterruptedException, ExecutionException {
           Future
   
     future = asyncService.asyncTaskD("Mr.nobody");        LOGGER.info("future result:" + future.get());        LOGGER.info("主线程执行...");    }}
   

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