spring 45 事件监听器

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// 事件解耦例子
@Configuration
public class A48_1 {
    public static void main(String[] args) {
        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(A48_1.class);
        context.getBean(MyService.class).dobusiness();
        context.close();
    }

    static class MyEvent extends ApplicationEvent {
        public MyEvent(Object source) {
            super(source);
        }
    }

    @Component
    static class MyService {
        private static final Logger log = LoggerFactory.getLogger(MyService.class);
        @Autowired
        private ApplicationEventPublisher publisher; // applicationContext
        public void dobusiness() {
            log.debug("主线业务");
            // 主线业务完成后需要做一些支线业务，下面是问题代码
            publisher.publishEvent(new MyEvent("MyService.dobusiness()"));
        }
    }

//    @Component
    static class SmsApplicationListener implements ApplicationListener<MyEvent> {
        private static final Logger log = LoggerFactory.getLogger(SmsApplicationListener.class);
        @Override
        public void onApplicationEvent(MyEvent event) {
            log.debug("发送短信");
        }
    }

    @Component
    static class EmailApplicationListener implements ApplicationListener<MyEvent> {
        private static final Logger log = LoggerFactory.getLogger(EmailApplicationListener.class);
        @Override
        public void onApplicationEvent(MyEvent event) {
            log.debug("发送邮件");
        }
    }

}

//注解实现
@Configuration
public class A48_2 {
    public static void main(String[] args) {
        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(A48_2.class);
        context.getBean(MyService.class).dobusiness();
        context.close();
    }

    static class MyEvent extends ApplicationEvent {
        public MyEvent(Object source) {
            super(source);
        }
    }

    @Component
    static class MyService {
        private static final Logger log = LoggerFactory.getLogger(MyService.class);
        @Autowired
        private ApplicationEventPublisher publisher; // applicationContext
        public void dobusiness() {
            log.debug("主线业务");
            // 主线业务完成后需要做一些支线业务，下面是问题代码
            publisher.publishEvent(new MyEvent("MyService.dobusiness()"));
        }
    }

    @Component
    static class SmsService {
        private static final Logger log = LoggerFactory.getLogger(SmsService.class);
        @EventListener
        public void listener(MyEvent myEvent) {
            log.debug("发送短信");
        }
    }

    @Component
    static class EmailService {
        private static final Logger log = LoggerFactory.getLogger(EmailService.class);
        @EventListener
        public void listener(MyEvent myEvent) {
            log.debug("发送邮件");
        }
    }

    //提供一个线程池，异步进行事件处理。
    @Bean
    public ThreadPoolTaskExecutor executor() {
        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        executor.setCorePoolSize(3);
        executor.setMaxPoolSize(10);
        executor.setQueueCapacity(100);
        return executor;
    }

    @Bean
    public SimpleApplicationEventMulticaster applicationEventMulticaster(ThreadPoolTaskExecutor executor) {
        SimpleApplicationEventMulticaster multicaster = new SimpleApplicationEventMulticaster();
        multicaster.setTaskExecutor(executor);
        return multicaster;
    }

}

//自定义注解
@Configuration
public class A48_3 {
    public static void main(String[] args) {
        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(A48_3.class);
        context.getBean(MyService.class).dobusiness();
        context.close();
    }

    @Bean
    public SmartinitializingSingleton smartinitializingSingleton(ConfigurableApplicationContext context) {
        return () -> {
            for (String name : context.getBeanDeFinitionNames()) {
                Object bean = context.getBean(name);
                for (Method method : bean.getClass().getmethods()) {
                    if (method.isAnnotationPresent(MyListener.class)) {
                        context.addApplicationListener((event) -> {
                            System.out.println(event);
                            Class<?> eventType = method.getParameterTypes()[0];// 监听器方法需要的事件类型
                            if (eventType.isAssignableFrom(event.getClass())) {
                                try {
                                    method.invoke(bean, event);
                                } catch (Exception e) {
                                    e.printstacktrace();
                                }
                            }
                        });
                    }
                }
            }
        };
    }

    @Component
    static class MyService {
        private static final Logger log = LoggerFactory.getLogger(MyService.class);
        @Autowired
        private ApplicationEventPublisher publisher; // applicationContext

        public void dobusiness() {
            log.debug("主线业务");
            // 主线业务完成后需要做一些支线业务，下面是问题代码
            publisher.publishEvent(new MyEvent("MyService.dobusiness()"));
        }
    }

    @Component
    static class SmsService {
        private static final Logger log = LoggerFactory.getLogger(SmsService.class);

        @MyListener
        public void listener(MyEvent myEvent) {
            log.debug("发送短信");
        }
    }

    @Component
    static class EmailService {
        private static final Logger log = LoggerFactory.getLogger(EmailService.class);

        @MyListener
        public void listener(MyEvent myEvent) {
            log.debug("发送邮件");
        }
    }

    @Retention(RetentionPolicy.RUNTIME)
    @Target(ElementType.METHOD)
    @interface MyListener {
    }

    static class MyEvent extends ApplicationEvent {
        public MyEvent(Object source) {
            super(source);
        }
    }
}

小结

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