介绍 spring的监听器也可以说是一种观察者模式,它能实现事件与事件监听者直接的解耦,在Spring中监听器的实现主要有一下重要组件: ApplicationListener:事件监听者,观察者;ApplicationEvent:Spri
spring的监听器也可以说是一种观察者模式,它能实现事件与事件监听者直接的解耦,在Spring中监听器的实现主要有一下重要组件:
SpringBoot进行事件监听有四种方式:
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。注意:该接口的实现类必须放到IOC容器中,否者不会起作用。
import org.springframework.context.ApplicationEvent;public class MyEvent extends ApplicationEvent { private Long id; private String name; public MyEvent(Long id, String name) { super(id); this.name = name; } public Long getId() { return id; } public void setId(Long id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; }}
import org.springframework.beans.factory.annotation.Autowired;import org.springframework.context.ApplicationEventPublisher;import org.springframework.stereotype.Component;@Componentpublic class MyEventPublisher { @Autowired private ApplicationEventPublisher applicationEventPublisher; public void publishEvent(Long id, String name) { MyEvent event = new MyEvent(id,name); applicationEventPublisher.publishEvent(event); }}
首先创建MyListener1类
public class MyListener1 implements ApplicationListener{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
@SpringBootApplicationpublic class LisenterApplication{public static void main(String[] args){ConfigurableApplicationContext context = SpringApplication.run(LisenterApplication.class, args);//装载监听context.addApplicationListener(new MyListener1());}}
创建MyListener2类,并使用@Component注解将该类装载入spring容器中
@Componentpublic class MyListener2 implements ApplicationListener{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()));}}
首先创建MyListener3类
public class MyListener3 implements ApplicationListener{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
创建MyListener4类,该类无需实现ApplicationListener接口,使用@EventListener装饰具体方法
@Componentpublic class MyListener4{Logger logger = Logger.getLogger(MyListener4.class); // @EventListener 注解支持根据Event参数类型进行匹配@EventListenerpublic void listener(MyEvent event){logger.info(String.format("%s监听到事件源:%s.", MyListener4.class.getName(), event.getSource()));}}
有些时候我们事件传递的对象是一些简单的对象,比如一个字符串,不想继承ApplicationEvent对象,可以使用PayloadApplicationEvent
@Componentpublic class PayloadApplicationListener implements ApplicationListener> { @Override public void onApplicationEvent(PayloadApplicationEvent event) { System.out.println(event.getPayload()); }}
public static void main(String[] args) { ApplicationContext applicationContext = new AnnotationConfigApplicationContext(AppConfig.class); //applicationContext.publishEvent(new InitializePost(applicationContext, "Y")); applicationContext.publishEvent("hello world"); //applicationContext.publishEvent(new C()); }
运行结果
hello world
来源地址:https://blog.csdn.net/ToBeMaybe_/article/details/130220766
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本文标题: SpringBoot 监听器
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