CommandLineRunner接口的作用

在平常开发中可能需要实现在启动后执行的功能，Springboot提供了一种简单的实现方案，即实现CommandLineRunner接口，实现功能的代码在接口的run方法里。

import org.springframework.core.annotation.Order;
public interface CommandLineRunner {
    
    
    /**
     * Callback used to run the bean.
     * @param args incoming main method arguments
     * @throws Exception on error
     */
    void run(String... args) throws Exception;
}

代码样式

package com.lucky.spring;

import com.alibaba.druid.pool.DruidDataSource;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.EnvironmentAware;
import org.springframework.context.annotation.Bean;
import org.springframework.core.env.Environment;

import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.SQLException;

@SpringBootApplication
public class Application implements CommandLineRunner {
    
    


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

    }

    @Override
    public void run(String... args) throws Exception {
    
    
        System.out.println(">>>>>>>>>>>>>>>>>服务启动执行");
    }
}

当服务中有多个CommandLineRunner对象时，默认情况下是按照自然顺序执行的。可以通过@Order指定执行顺序。
@Order注解学习

@Component
@Order(value = 1)
public class StartRunnerOne implements CommandLineRunner {
    
    

    @Override
    public void run(String... args) throws Exception {
    
    
        System.out.println(">>>>>>>>>>>>>>>服务启动第一个开始执行的任务，执行加载数据等操作<<<<<<<<<<<<<");
    }
}

@Component
@Order(value = 2)
public class StartupRunnerTwo implements CommandLineRunner {
    
    

    @Override
    public void run(String... args) throws Exception {
    
    
        System.out.println(">>>>>>>>>>>>>>>服务第二顺序启动执行，执行加载数据等操作<<<<<<<<<<<<<");
    }
}