SpringBoot使用异步@EnableAsync、@Async

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，比如3位理发师，5位顾客来理发。

下面上代码

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
@Configuration
public 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方法上面添加 @Async(value = "taskExecutor")表示方法异步，异步的方法不能被当前类的方法互相调用，在同一个类内部调用一个异步方法，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
@Slf4j
public class DemoServiceImpl {

    @Async(value = "taskExecutor")
    public void haircut(CountDownLatch countDownLatch, String user) {
        log.info("用户:{},开始理发", user);
        try {
            //模拟耗时
            Thread.sleep(5000L);
        } catch (InterruptedException e) {
        }
        log.info("用户:{},理发完成", user);
        countDownLatch.countDown();
    }
}

写一个单侧，营业开始，5为顾客来理发，都理发完成，营业结束

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
@Slf4j
public 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:关闭营业");
    }
}

运行结果如下：时间点和效果符合预期

CountDownLatch 定义了5个顾客同时来理发，实际并发还是按照线程池配置3个理发师来处理的

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,理发完成
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,理发完成
2022-10-19 18:04:15.380 [taskExecutor-2] INFO  org.sauceggplant.manage.demo.service.impl.DemoServiceImpl[20] - 用户:李四,理发完成
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,理发完成
2022-10-19 18:04:20.380 [taskExecutor-1] INFO  org.sauceggplant.manage.demo.service.impl.DemoServiceImpl[20] - 用户:孙七,理发完成
2022-10-19 18:04:20.381 [main] INFO  org.sauceggplant.manage.demo.service.impl.DemoServiceImplTest[29] - 理发店:关闭营业

感兴趣童鞋可以自己试一下，good luck!