Springboot进行事件监听的四种方式

前言

讲到事件监听，这里我们说下自定义事件和自定义监听器类的实现方式：
自定义事件：继承自ApplicationEvent抽象类，然后定义自己的构造器
自定义监听：实现ApplicationListener接口，然后实现onApplicationEvent方法

下面讲下4种事件监听的具体实现

1.手工向ApplicationContext中添加监听器

首先创建MyListener1类

public class MyListener1 implements ApplicationListener<MyEvent>{Logger logger = Logger.getLogger(MyListener1.class);public void onApplicationEvent(MyEvent event){logger.info(String.format("%s监听到事件源：%s.", MyListener1.class.getName(), event.getSource()));}
}

然后在springboot应用启动类中获取ConfigurableApplicationContext上下文，装载监听

@SpringBootApplication
public class LisenterApplication{public static void main(String[] args){ConfigurableApplicationContext context = SpringApplication.run(LisenterApplication.class, args);//装载监听context.addApplicationListener(new MyListener1());}
}

2.将监听器装载入spring容器

创建MyListener2类，并使用@Component注解将该类装载入spring容器中

@Component
public class MyListener2 implements ApplicationListener<MyEvent>{Logger logger = Logger.getLogger(MyListener2.class);public void onApplicationEvent(MyEvent event) {logger.info(String.format("%s监听到事件源：%s.", MyListener2.class.getName(), event.getSource()));}
}

3.在application.properties中配置监听器

首先创建MyListener3类

public class MyListener3 implements ApplicationListener<MyEvent>{Logger logger = Logger.getLogger(MyListener3.class);public void onApplicationEvent(MyEvent event){logger.info(String.format("%s监听到事件源：%s.", MyListener3.class.getName(), event.getSource()));}
}

然后在application.properties中配置监听

context.listener.classes=com.listener.MyListener3

4.通过@EventListener注解实现事件监听

创建MyListener4类，该类无需实现ApplicationListener接口，使用@EventListener装饰具体方法

@Component
public class MyListener4{Logger logger = Logger.getLogger(MyListener4.class);@EventListenerpublic void listener(MyEvent event){logger.info(String.format("%s监听到事件源：%s.", MyListener4.class.getName(), event.getSource()));}
}

自定义事件代码如下：

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

进行测试(在启动类中加入发布事件的逻辑)：

@SpringBootApplication
public class LisenterApplication{@Autowiredprivate ApplicationEventPublisher applicationEventPublisher;@Autowiredprivate ApplicationContext applicationContext;public static void main(String[] args){ConfigurableApplicationContext context =         SpringApplication.run(LisenterApplication.class, args);//装载事件context.addApplicationListener(new MyListener1());//发布事件方式1context.publishEvent(new MyEvent("测试事件."));//发布事件方式2applicationEventPublisher.publishEvent(new MyEvent("测试事件."));//发布事件方式3applicationContext.publishEvent(new MyEvent("测试事件."));}
}

启动后，日志打印如下：

2022-06-15 10:51:20.198  INFO 4628 --- [           main] com.listener.MyListener3                 : com.listener.MyListener3监听到事件源：测试事件..
2022-06-15 10:51:20.198  INFO 4628 --- [           main] com.listener.MyListener4                 : com.listener.MyListener4监听到事件源：测试事件..
2022-06-15 10:51:20.199  INFO 4628 --- [           main] com.listener.MyListener2                 : com.listener.MyListener2监听到事件源：测试事件..
2022-06-15 10:51:20.199  INFO 4628 --- [           main] com.listener.MyListener1                 : com.listener.MyListener1监听到事件源：测试事件..