Springboot中的CommandLineRunner

CommandLineRunner接口的作用

在平常開發中可能需要實現在啟動后執行的功能，Springboot提供了一種簡單的實現方案，即實現CommandLineRunner接口，實現功能的代碼在接口的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;
}

實現代碼

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(">>>>>>>>>>>>>>>>>服務啟動執行");
    }
}

當服務中有多個CommandLineRunner對象時，默認情況下是按照自然順序執行的。可以通過@Order指定執行順序。

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

    @Override
    public void run(String... args) throws Exception {
        System.out.println(">>>>>>>>>>>>>>>服務啟動第一個開始執行的任務，執行加載數據等操作<<<<<<<<<<<<<");
    }
}

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

    @Override
    public void run(String... args) throws Exception {
        System.out.println(">>>>>>>>>>>>>>>服務第二順序啟動執行，執行加載數據等操作<<<<<<<<<<<<<");
    }
}