Spring boot通过@EnableAsync、@Async配合来实现异步调用的。
举一个理发店的例子吧，比方3位理发师，5位顾客来理发。
上面上代码
通过@EnableAsync、@Configuration配置一个默认的线程池，充当理发师CorePoolSize(3);即3位理发师
import org.springframework.aop.interceptor.AsyncExecutionAspectSupport;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;import org.springframework.scheduling.annotation.EnableAsync;import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;import java.util.concurrent.Executor;import java.util.concurrent.ThreadPoolExecutor;@EnableAsync@Configurationpublic class ThreadPoolConfig { @Bean(name = AsyncExecutionAspectSupport.DEFAULT_TASK_EXECUTOR_BEAN_NAME) public Executor taskExecutor() { ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor(); executor.setCorePoolSize(3); executor.setMaxPoolSize(3); executor.setQueueCapacity(10); executor.setKeepAliveSeconds(60); executor.setThreadGroupName("理发师-"); executor.setWaitForTasksToCompleteOnShutdown(true); executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy()); return executor; }}理发业务,haircut办法下面增加 @Async(value = "taskExecutor")示意办法异步，异步的办法不能被以后类的办法相互调用，在同一个类外部调用一个异步办法，不会触发异步
import lombok.extern.slf4j.Slf4j;import org.springframework.scheduling.annotation.Async;import org.springframework.stereotype.Service;import java.util.concurrent.CountDownLatch;@Service@Slf4jpublic class DemoServiceImpl { @Async(value = "taskExecutor") public void haircut(CountDownLatch countDownLatch, String user) { log.info("用户:{},开始理发", user); try { //模仿耗时 Thread.sleep(5000L); } catch (InterruptedException e) { } log.info("用户:{},理发实现", user); countDownLatch.countDown(); }}写一个单侧，营业开始，5为顾客来理发，都理发实现，营业完结
import lombok.extern.slf4j.Slf4j;import org.junit.jupiter.api.Test;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.boot.test.context.SpringBootTest;import java.util.concurrent.CountDownLatch;@SpringBootTest@Slf4jpublic class DemoServiceImplTest { @Autowired private DemoServiceImpl demoService; @Test public void haircutBusiness() { log.info("理发店:开始营业"); CountDownLatch countDownLatch = new CountDownLatch(5); demoService.haircut(countDownLatch, "张三"); demoService.haircut(countDownLatch, "李四"); demoService.haircut(countDownLatch, "王五"); demoService.haircut(countDownLatch, "马六"); demoService.haircut(countDownLatch, "孙七"); try { countDownLatch.await(); } catch (InterruptedException e) { } log.info("理发店:敞开营业"); }}运行后果如下：工夫点和成果合乎预期
CountDownLatch 定义了5个顾客同时来理发，理论并发还是依照线程池配置3个理发师来解决的
2022-10-19 18:04:10.356 [main] INFO org.sauceggplant.manage.demo.service.impl.DemoServiceImplTest[19] - 理发店:开始营业2022-10-19 18:04:10.363 [taskExecutor-1] INFO org.sauceggplant.manage.demo.service.impl.DemoServiceImpl[15] - 用户:张三,开始理发2022-10-19 18:04:10.363 [taskExecutor-2] INFO org.sauceggplant.manage.demo.service.impl.DemoServiceImpl[15] - 用户:李四,开始理发2022-10-19 18:04:10.363 [taskExecutor-3] INFO org.sauceggplant.manage.demo.service.impl.DemoServiceImpl[15] - 用户:王五,开始理发2022-10-19 18:04:15.379 [taskExecutor-3] INFO org.sauceggplant.manage.demo.service.impl.DemoServiceImpl[20] - 用户:王五,理发实现2022-10-19 18:04:15.379 [taskExecutor-3] INFO org.sauceggplant.manage.demo.service.impl.DemoServiceImpl[15] - 用户:马六,开始理发2022-10-19 18:04:15.379 [taskExecutor-1] INFO org.sauceggplant.manage.demo.service.impl.DemoServiceImpl[20] - 用户:张三,理发实现2022-10-19 18:04:15.380 [taskExecutor-2] INFO org.sauceggplant.manage.demo.service.impl.DemoServiceImpl[20] - 用户:李四,理发实现2022-10-19 18:04:15.380 [taskExecutor-1] INFO org.sauceggplant.manage.demo.service.impl.DemoServiceImpl[15] - 用户:孙七,开始理发2022-10-19 18:04:20.380 [taskExecutor-3] INFO org.sauceggplant.manage.demo.service.impl.DemoServiceImpl[20] - 用户:马六,理发实现2022-10-19 18:04:20.380 [taskExecutor-1] INFO org.sauceggplant.manage.demo.service.impl.DemoServiceImpl[20] - 用户:孙七,理发实现2022-10-19 18:04:20.381 [main] INFO org.sauceggplant.manage.demo.service.impl.DemoServiceImplTest[29] - 理发店:敞开营业感兴趣童鞋能够本人试一下，good luck!