spring事件监听器

一、核心结构： 定义事件捕捉类并实现ApplicationListener<泛型:表示要捕获的事件对象>

然后用@Component注解为此事件捕捉类创建对象，并纳入容器中。

二、项目结构：

三、项目代码：

1.监听器：

package com.zyq.event;

import org.springframework.context.ApplicationListener;
import org.springframework.context.event.ContextStartedEvent;
import org.springframework.context.event.ContextStoppedEvent;
import org.springframework.stereotype.Component;

@Component
public class ContextStartEventHandler implements ApplicationListener<ContextStartedEvent> {
    //此方法在容器启动时执行
    public void onApplicationEvent(ContextStartedEvent contextStartedEvent) {
        System.out.println("context started event received");
    }
}

@Component
class CStopEventHandler   implements ApplicationListener<ContextStoppedEvent> {
    //此方法在容器停止运行时执行
    public void onApplicationEvent(ContextStoppedEvent contextStoppedEvent) {
        System.out.println("context stoped event received");
    }
}

2.从spring容器中获取的对象：

package com.zyq.event;

import lombok.Data;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component
@Data
public class HelloWorld {
    @Value("hello")
    private String message;
}

3.测试类(注意：这个案例中去掉HelloWorld类，监听器也是可以工作的)：

package com.zyq.test;

import com.zyq.event.HelloWorld;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class TestCase {
    public static void main(String[] args) {
        ConfigurableApplicationContext context =
                new ClassPathXmlApplicationContext("springmvc-servlet.xml");

        // Let us raise a start event.
        context.start();

        HelloWorld obj = (HelloWorld) context.getBean("helloWorld");

        System.out.println("helloWorldMsg:"+obj.getMessage());

        // Let us raise a stop event.
        context.stop();
    }
}

4.spring核心配置文件

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.1.xsd
        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.1.xsd">

    <!-- scan the package and the sub package -->
    <context:component-scan base-package="com"/>

    <!-- don't handle the static resource: 不拦截静态资源 -->
    <mvc:default-servlet-handler/>

    <!-- if you use annotation you must configure following setting -->
    <mvc:annotation-driven/>

</beans>

5.pom.xml

  <groupId>org.zyq</groupId>
  <artifactId>4_springEventDemo</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>war</packaging>

  <name>4_springEventDemo Maven Webapp</name>
  <!-- FIXME change it to the project's website -->
  <url>http://www.example.com</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
  </properties>

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>org.projectlombok</groupId>
      <artifactId>lombok</artifactId>
      <version>RELEASE</version>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-webmvc</artifactId>
      <version>4.3.8.RELEASE</version>
    </dependency>
    <dependency>
      <groupId>org.junit.jupiter</groupId>
      <artifactId>junit-jupiter</artifactId>
      <version>RELEASE</version>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>3.0.1</version>
      <scope>provided</scope>
    </dependency>
    <dependency>
      <groupId>javax.servlet.jsp</groupId>
      <artifactId>jsp-api</artifactId>
      <version>2.2</version>
      <scope>provided</scope>
    </dependency>
  </dependencies>