详解SpringBoot程序启动时执行初始化代码

package com.stone;

import com.stone.service.IPermissionService;
import org.springframework.context.ApplicationListener;
import org.springframework.context.event.ContextRefreshedEvent;

/**
 * @author Stone Yuan
 * @create 2017-12-02 21:54
 * @description
 */
public class ApplicationStartup implements ApplicationListener<ContextRefreshedEvent> {

  @Override
  public void onApplicationEvent(ContextRefreshedEvent contextRefreshedEvent) {
    IPermissionService service = contextRefreshedEvent.getApplicationContext().getBean(IPermissionService.class);
    service.loadUserPermissionIntoRedis();
  }
}

package com.stone;

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

@SpringBootApplication
public class YwythApplication {

  public static void main(String[] args) {
    SpringApplication springApplication = new SpringApplication(YwythApplication.class);
    springApplication.addListeners(new ApplicationStartup());
    springApplication.run(args);
  }
}

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.context.EnvironmentAware;
import org.springframework.core.annotation.Order;
import org.springframework.core.env.Environment;
import org.springframework.stereotype.Component;

import java.util.List;

@Component
//如果有多个这样的类时，可以通过Order指定执行顺序，数值越小执行优先级越高
@Order(value = 0)
public class InitSystemConfig implements CommandLineRunner, EnvironmentAware {


  /*
   * 在服务启动后执行，会在@Bean实例化之后执行，故如果@Bean需要依赖这里的话会出问题
   */
  @Override
  public void run(String... args) {

    //这里可以根据数据库返回结果创建一些对象、启动一些线程等
    

  }

  /*
   * 在SystemConfigDao实例化之后、@Bean实例化之前执行
   * 常用于读取数据库配置以供其它bean使用
   * environment对象可以获取配置文件的配置，也可以把配置设置到该对象中
   */
  @Override
  public void setEnvironment(Environment environment) {

  }
}