SpringBoot中ApplicationListener事件监听的6种方式_addapplicationlistener()-优快云博客

本文链接：https://blog.youkuaiyun.com/weixin_36586564/article/details/118492076

本文详细介绍了如何在Spring Boot应用中通过不同方式添加监听器，包括通过`ApplicationListener`接口、组件注解、配置文件、`@EventListener`、`spring.factories`和编程式初始化。重点演示了如何在ApplicationContext中注册并监听TestEvent事件。

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Event事件：

import org.springframework.context.ApplicationEvent;

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

文章目录

一、向ApplicationContext中添加监听器

public class TestListener1 implements ApplicationListener<TestEvent> {
    Logger logger = LoggerFactory.getLogger(TestListener1.class);

    @Override
    public void onApplicationEvent(TestEvent event) {
        logger.info(String.format("%s  监听到事件源：%s.", TestListener1.class.getName(), event.getSource()));
    }
}

要点是spring上下文中加入监听器

@SpringBootApplication
public class Application {
    public static void main(String[] args) {
        ConfigurableApplicationContext context = SpringApplication.run(Application.class,args);
        //装载监听
        context.addApplicationListener(new TestListener1());
        context.publishEvent(new TestEvent("启动时作出如下动作！"));
    }
}

二、将监听器作为组件交给spring容器管理

要点：@Component声明

@Component
public class TestListener2 implements ApplicationListener<TestEvent> {
    Logger logger = LoggerFactory.getLogger(TestListener2.class);

    @Override
    public void onApplicationEvent(TestEvent event) {
        logger.info(String.format("%s  监听到事件源：%s.", TestListener2.class.getName(), event.getSource()));

    }
}

@SpringBootApplication
public class Application {

    public static void main(String[] args) {
        ConfigurableApplicationContext context = SpringApplication.run(Application.class,args);
        context.publishEvent(new TestEvent("启动时作出如下动作！"));
}

三、在application.properties中配置监听器context.listener.classes

public class TestListener3 implements ApplicationListener<TestEvent> {
    Logger logger = LoggerFactory.getLogger(TestListener3.class);

    @Override
    public void onApplicationEvent(TestEvent event) {
        logger.info(String.format("%s  监听到事件源：%s.", TestListener3.class.getName(), event.getSource()));

    }
}

@SpringBootApplication
public class Application {

    public static void main(String[] args) {
        ConfigurableApplicationContext context = SpringApplication.run(Application.class,args);
        context.publishEvent(new TestEvent("启动时作出如下动作！"));
}

这种方式有个问题：测试时监听器会执行2遍。

四、通过@EventListener注解实现事件监听

@Component
public class TestListener4 {
    Logger logger = LoggerFactory.getLogger(TestListener4.class);

    @EventListener
    public void onApplicationEvent(TestEvent event) {
        logger.info(String.format("%s  监听到事件源：%s.", TestListener4.class.getName(), event.getSource()));

    }
}

@SpringBootApplication
public class Application {

    public static void main(String[] args) {
        ConfigurableApplicationContext context = SpringApplication.run(Application.class,args);
        context.publishEvent(new TestEvent("启动时作出如下动作！"));
}

五、配置spring.factories

public class TestListener5 implements ApplicationListener<TestEvent> {
    Logger logger = LoggerFactory.getLogger(TestListener5.class);

    @Override
    public void onApplicationEvent(TestEvent event) {
        logger.info(String.format("%s  监听到事件源：%s.", TestListener5.class.getName(), event.getSource()));
    }
}

在这里插入图片描述

@SpringBootApplication
public class Application {

    public static void main(String[] args) {
        ConfigurableApplicationContext context = SpringApplication.run(Application.class,args);
        context.publishEvent(new TestEvent("启动时作出如下动作！"));
}

六、通过实现接口org.springframework.context.ApplicationContextInitializer,得到context后通过编程式,设置监听器

public class TestListener6 implements ApplicationListener<TestEvent> , ApplicationContextInitializer {
    Logger logger = LoggerFactory.getLogger(TestListener6.class);

    @Override
    public void onApplicationEvent(TestEvent event) {
        logger.info(String.format("%s  监听到事件源：%s.", TestListener6.class.getName(), event.getSource()));
    }

    @Override
    public void initialize(ConfigurableApplicationContext applicationContext) {
        applicationContext.addApplicationListener(new TestListener6());
    }
}

@SpringBootApplication
public class Application {

    public static void main(String[] args) {
        SpringApplication springApplication = new SpringApplication(Application.class);
        springApplication.addInitializers(new TestListener6());
        ConfigurableApplicationContext context = springApplication.run(args);
        //发布事件
        context.publishEvent(new TestEvent("启动时作出如下动作！"));
    }

}

七、测试运行结果

统一运行：

@SpringBootApplication
public class Application {

    public static void main(String[] args) {
        SpringApplication springApplication = new SpringApplication(Application.class);
        springApplication.addInitializers(new TestListener6());
        ConfigurableApplicationContext context = springApplication.run(args);
        //装载监听
        context.addApplicationListener(new TestListener1());
        //发布事件
        context.publishEvent(new TestEvent("启动时作出如下动作！"));
    }
}

在这里插入图片描述