springboot 中CommandLineRunner/ApplicationRunner接口的作用

先看CommandLineRunner 接口的API:

package org.springframework.boot;

import org.springframework.core.Ordered;
import org.springframework.core.annotation.Order;

@FunctionalInterface
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;

}
 

先看ApplicationRunner 接口的API:

package org.springframework.boot;

import org.springframework.core.Ordered;
import org.springframework.core.annotation.Order;

@FunctionalInterface
public interface ApplicationRunner {

   /**
    * Callback used to run the bean.
    * @param args incoming application arguments
    * @throws Exception on error
    */
   void run(ApplicationArguments args) throws Exception;

}
 

SpringBoot在項目啓動後會遍歷所有實現CommandLineRunner /ApplicationRunner 的實體類並執行run方法，如果需要按照一定的順序去執行，那麼就需要在實體類上使用一個@Order註解【 @Order(value=1..)】（或者實現Order接口）來表明順序.

import org.springframework.boot.CommandLineRunner;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;

@Component
@Order(value=1)
public class StartupRunnerOne implements CommandLineRunner {
    @Override
    public void run(String... args) throws Exception {
        System.out.println(">>>>>>>>>>>>>>>服務啓動第一個開始執行的任務，執行加載數據等操作<<<<<<<<<<<<<");
    }
}

 

import org.springframework.boot.ApplicationArguments;
import org.springframework.boot.ApplicationRunner;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;

@Component
@Order(value=2)
public class StartupRunnerOne3 implements ApplicationRunner {

    @Override
    public void run(ApplicationArguments args) throws Exception {
        System.out.println(">>>>>>>>>>服務啓動第二個開始執行的任務，執行加載數據等操作<<<<<<<<<<<<<");
    }
}