观察者模式之Spring: event和listener

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>cn.it</groupId>
    <artifactId>springmvc-test</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>jar</packaging>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-parent</artifactId>
        <version>2.2.2.RELEASE</version>
    </parent>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>


    <build>
        <resources>
            <!-- 指定了java和resources下的xml文件,xlsx文件,xls文件打包到根目录 -->
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>*.xml</include>
                    <include>**/*.xlsx</include>
                    <include>**/*.xls</include>
                </includes>
            </resource>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.yml</include>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>false</filtering>
            </resource>
        </resources>
        <plugins>
            <!--解决打包没有mainClass问题-->
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <version>2.2.6.RELEASE</version>
                <configuration>
                    <fork>true</fork>
                    <mainClass>com.power.app.AppWebApplication</mainClass>
                    <includeSystemScope>true</includeSystemScope>
                </configuration>
                <executions>
                    <execution>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
        <finalName>springmvc-test</finalName>
    </build>

</project>

main

package cn.it;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class ApplicationMain {

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

package cn.it.event;

import org.springframework.context.ApplicationEvent;

public class MyEvent extends ApplicationEvent {

    public MyEvent(Object source) {
        super(source);
        System.out.println("my Event");
    }

    public void print(){
        System.out.println("hello spring event[MyEvent]");
    }
}

package cn.it.event;

import org.springframework.context.ApplicationEvent;
import org.springframework.context.ApplicationListener;
import org.springframework.stereotype.Component;

@Component
public class MyListener implements ApplicationListener {

    public void onApplicationEvent(ApplicationEvent event) {
        if(event instanceof MyEvent){
            System.out.println("into My Listener");
            MyEvent myEvent=(MyEvent)event;
            myEvent.print();
        }
    }
}

package cn.it.event;

import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.ApplicationEvent;
import org.springframework.stereotype.Component;

@Component
public class MyPubisher implements ApplicationContextAware {

    private ApplicationContext applicationContext;

    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.applicationContext=applicationContext;
    }

    public void publishEvent(ApplicationEvent event){
        System.out.println("into My Publisher's method");
        applicationContext.publishEvent(event);
    }
}

package cn.it.event;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;

import javax.annotation.Resource;

@SpringBootTest
@RunWith(SpringRunner.class)
public class MyTest {

    @Resource
    MyPubisher myPublisher;

    @Test
    public void test(){
        MyEvent myEvent = new MyEvent("1");
        this.myPublisher.publishEvent(myEvent);
    }
}