@Async开启Spring异步调用

​ 在springboot环境可以通过@EnableAsync + @Async两个注解实现异步，必须使用@EnableAsync 开启，否则@Async不会生效。

配置方式

使用JavaConfig简单配置：

@Configuration
@EnableAsync
public class DefaultAsyncConfig {
}

默认使用org.springframework.core.task.SimpleAsyncTaskExecutor实现异步调用。

测试代码

@Component
public class TestService {
    private static final Logger logger = LoggerFactory.getLogger(TestService.class);
    @Async
    public void testAsync(){
        logger.info("Async Thread Name: {}", Thread.currentThread().getName());
    }
}

结果如下，每次线程名称都会增加：

2021-03-09 09:45:51.950  INFO 14636 --- [task-1] c.c.m.p.h.service.connect.TestService    : Async Thread Name: task-1
2021-03-09 09:46:09.953  INFO 14636 --- [task-2] c.c.m.p.h.service.connect.TestService    : Async Thread Name: task-2

自定义线程池

按照上面的配置，已经实现了异步调用，不过每次调用实际上是生成一个新的线程，比较浪费服务器资源。一般需要自定义配置线程池，然后异步调用的时候从线程池中获取线程，配置如下：

@Configuration
@EnableAsync
public class DefaultAsyncConfig implements AsyncConfigurer {
    @Override
    public AsyncUncaughtExceptionHandler getAsyncUncaughtExceptionHandler() {
        return new SimpleAsyncUncaughtExceptionHandler();
    }
    @Override
    public Executor getAsyncExecutor() {
        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        //核心线程数
        executor.setCorePoolSize(10);
        //最大线程数
        executor.setMaxPoolSize(30);
        //最大队列数
        executor.setQueueCapacity(500);
        //线程池中的线程的名称前缀
        executor.setThreadNamePrefix("cloud-service-async-");
        executor.setWaitForTasksToCompleteOnShutdown(true);
        executor.initialize();
        return executor;
    }
}

执行结果

2021-03-09 10:05:20.546  INFO 11372 --- [service-async-1] c.c.m.p.h.service.connect.TestService    : Async Thread Name: cloud-service-async-1
2021-03-09 10:05:20.966  INFO 11372 --- [service-async-2] c.c.m.p.h.service.connect.TestService    : Async Thread Name: cloud-service-async-2