spring boot2.1.1自定义Listener的两种方式

环境

idea 2019
jdk1.8
maven3.6
spring boot2.1.1(目前springboot最高版本为2.1.8情况下，2.0以上测试过几个版本都可正常运行)
项目类型：jar

导入spring boot web启动器依赖

<dependency>
 		<groupId>org.springframework.bootgroupId>
  	    <artifactId>spring-boot-starter-webartifactId>
dependency>

注意：spring boot自动配置的前提是>>所有组件都在核心启动类所在包及其子包下，所以本篇所有java类都是在核心类所在包及其子包下创建。

方式一（自动扫描）

创建一个类实现要监听的Listener接口，重写相关方法，在类上加@WebListener注解

package com.wn.demo.springboot.server;

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;

@WebListener
public class MyContextListener implements ServletContextListener {

    @Override
    public void contextInitialized(ServletContextEvent sce) {
        System.out.println("ContextListener init...");
    }

    @Override
    public void contextDestroyed(ServletContextEvent sce) {
        System.out.println("ContextListener destory...");
    }
}

在配置类上添加@ServletComponentScan注解，这里方便起见就加在核心启动类上

package com.wn.demo.springboot;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;

@ServletComponentScan // 自动扫描自定义的Listener组件
@SpringBootApplication
public class SpringBootWeb2Application {

    public static void main(String[] args) {
        SpringApplication.run(SpringBootWeb2Application.class, args);
    }

}

方式二（手动注册）

创建一个类实现要监听的Listener接口,重写相关方法

package com.wn.demo.springbootrestfulcrud.server;

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;

public class MyListener implements ServletContextListener {
    @Override
    public void contextInitialized(ServletContextEvent sce) {
        System.out.println("MyListener 启动");
    }

    @Override
    public void contextDestroyed(ServletContextEvent sce) {
        System.out.println("MyListener 销毁");
    }
}

在配置类中注册Listener

package com.wn.demo.springbootrestfulcrud.config;

import com.wn.demo.springbootrestfulcrud.server.MyFilter;
import com.wn.demo.springbootrestfulcrud.server.MyListener;
import com.wn.demo.springbootrestfulcrud.server.MyServlet;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.boot.web.servlet.ServletListenerRegistrationBean;
import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import java.util.Arrays;

/**
 * server相关配置
 */
@Configuration
public class MyServerConfig {
    /**
     * 注册listener
     * @return Listener注册对象
     */
    @Bean
    public ServletListenerRegistrationBean<MyListener> myListener() {
    	// 创建Listener注册对象，将自定义的Listener作为构造参数传入
        return new ServletListenerRegistrationBean<>(new MyListener());
    }

}