SpringEvent事件机制

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前言

Spring Event 机制使用起来比较简单。

  • 需要一个事件类
  • 需要监听当前事件类
  • 需要发布当前事件类的事件

简单了解一下

ApplicationEventPublisher用来发布事件，默认实现类 AbstractApplicationContext.

其中 ApplicationEventPublisher有两个 publishEvent 方法，在Spring Context 4.2之后就没有区别了。

demo

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@SpringBootApplication
public class StartSpringBootEventDemoApplication {

    public static void main(String[] args) {
        SpringApplication application = new SpringApplication(StartSpringBootEventDemoApplication.class);
        application.run(args);
    }

    @Bean
    public CommandLineRunner test(ApplicationEventPublisher applicationEventPublisher) {
        return args -> {
            /*发布事件*/
            applicationEventPublisher.publishEvent(new CustomEvent(11111));
            applicationEventPublisher.publishEvent(new CustomEvent2(22222));
        };
    }

    /**
     * 测试自定义事件类
     */
    public static class CustomEvent {
        /**
         * 标识
         */
        private final int id;

        public CustomEvent(int id) {
            this.id = id;
        }

        @Override
        public String toString() {
            return "CustomEvent{" + "id=" + id + '}';
        }
    }

    /**
     * 测试自定义事件类
     */
    public static class CustomEvent2 {
        /**
         * 标识
         */
        private final int id;

        public CustomEvent2(int id) {
            this.id = id;
        }

        @Override
        public String toString() {
            return "CustomEvent2{" + "id=" + id + '}';
        }
    }

    /**
     * 监听事件
     */
    @EventListener(value = CustomEvent.class)
    public void listener(CustomEvent customEvent) {
        System.out.println("listener=>" + customEvent);
    }

    @EventListener
    public void listener2(CustomEvent customEvent) {
        System.out.println("listener2=>" + customEvent);
    }

    @EventListener(value = CustomEvent2.class)
    public void listener3(CustomEvent2 customEvent) {
        System.out.println("listener3=>" + customEvent);
    }

    @EventListener
    public void listener4(CustomEvent2 customEvent) {
        System.out.println("listener4=>" + customEvent);
    }

    @EventListener(value = {CustomEvent.class, CustomEvent2.class})
    public void listener5(Object customEvent) {
        System.out.println("listener5=>" + customEvent);
    }

}

上面会输出

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listener=>CustomEvent{id=11111}
listener5=>CustomEvent{id=11111}
listener2=>CustomEvent{id=11111}
listener3=>CustomEvent2{id=22222}
listener5=>CustomEvent2{id=22222}
listener4=>CustomEvent2{id=22222}

引入依赖

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<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter</artifactId>
    </dependency>
</dependencies>

本文地址： https://github.com/maxzhao-it/blog/post/ff3733f2/