SpringBoot ApplicationListener监听器的使用-监听ApplicationReadyEvent事件

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SpringBoot监听器

ApplicationContext事件机制是观察者设计模式的实现，通过ApplicationEvent类和ApplicationListener接口，可以实现ApplicationContext事件处理。
如果容器中有一个ApplicationListener Bean，每当ApplicationContext发布ApplicationEvent时，ApplicationListener Bean将自动被触发。这种事件机制都必须需要程序显示的触发。

spring boot中支持的事件类型如下：

• ApplicationFailedEvent：该事件为spring boot启动失败时的操作
• ApplicationPreparedEvent：上下文context准备时触发
• ApplicationReadyEvent：上下文已经准备完毕的时候触发
• ApplicationStartedEvent：spring boot 启动监听类
• SpringApplicationEvent：获取SpringApplication
• ApplicationEnvironmentPreparedEvent：环境事先准备

SpringBoot监听ApplicationReadyEvent事件用例

自定义监听器

解决mybatis多数据源，可以在项目启动的时候候指定数据源

package com.sl.listener;

import org.mybatis.spring.SqlSessionTemplate;
import org.mybatis.spring.support.SqlSessionDaoSupport;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.context.event.ApplicationReadyEvent;
import org.springframework.context.ApplicationListener;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.stream.Stream;


/**
 * @author shuliangzhao
 * @Title: MyApplicationEventListener
 * @ProjectName spring-boot-learn
 * @Description: TODO
 * @date 2019/10/17 20:24
 */
@Component
public class MyApplicationEventListener implements ApplicationListener<ApplicationReadyEvent> {


    @Resource(name = "targetSqlSessionTemplate")
    private SqlSessionTemplate targetSqlSessionTemplate;
    
    @Resource(name = "midSqlSessionTemplate")
    private SqlSessionTemplate midSqlSessionTemplate;

    //包名 不同的包名以逗号分隔
    @Value("{taget.source}")
    private String targetSource;

    //包名
    @Value("{mid.source}")
    private String midSource;

    @Override
    public void onApplicationEvent(ApplicationReadyEvent applicationReadyEvent) {
        ConfigurableApplicationContext applicationContext = applicationReadyEvent.getApplicationContext();
        Map<String, SqlSessionDaoSupport> beanMap = applicationContext.getBeansOfType(SqlSessionDaoSupport.class);
        String[] targetScanPath = targetSource.split(",");
        String[] midScanPath = midSource.split(",");
        List<String> targetList = Arrays.asList(targetScanPath);
        List<String> midList = Arrays.asList(midScanPath);
        beanMap.forEach((k,v) -> {
            String name = v.getClass().getPackage().getName();
            if (targetList.contains(name)) {
                v.setSqlSessionTemplate(targetSqlSessionTemplate);
            }else if (midList.contains(name)) {
                v.setSqlSessionTemplate(midSqlSessionTemplate);
            }                                                 
        } );
    }
}