Spring Cloud微服务实战打造企业级优惠券系统 3-9 SpringBoot开机启动

0　　　　课程地址

http://coding.imooc.com/lesson/380.html#mid=28360

1　　　　浓缩精华

2.1，4.1，4.2

2　　　　个人关注

2.1　　initializingbean开启启动和本节两种开机启动有什么优劣

这个问题提的挺好的，我来做一些解释。首先，我们可以看一看 InitializingBean 的定义：

public interface InitializingBean {
    void afterPropertiesSet() throws Exception;
}

InitializingBean 接口为 bean 提供了属性初始化后的处理方法，它只包括 afterPropertiesSet 方法，凡是继承该接口的类，在 bean 的属性初始化后都会执行该方法。

但是，需要注意的是，InitializingBean 是在当前的 Bean 初始化完成之后就去执行的。而我在课程中讲到的 ApplicationRunner 和 CommandLineRunner 则是在所有的 Bean 都初始化完成之后才会去执行。所以，我们可以在 ApplicationRunner 和 CommandLineRunner 中直接注入系统中的 bean 做一些操作。

另外，InitializingBean 是 Spring 框架的接口，而 ApplicationRunner 和 CommandLineRunner 则是 SpringBoot 提供的接口。

不过，通常来说，如果开机启动的任务没有依赖，使用任何一种方式都是可行的，区别不大。

3　　　　课程内容

3.1　　课程内容

两种开机启动方式以及@Order注解的应用

4　　　　代码演练

4.1　　两种开启启动方式（ApplicationRunner和CommandRunner）（ApplicationRunner先启动）

BootApplicationRunner

package com.imooc.springboot.application.study;

import lombok.extern.slf4j.Slf4j;
import org.springframework.boot.ApplicationArguments;
import org.springframework.boot.ApplicationRunner;
import org.springframework.stereotype.Component;

/**
 * BootApplicationRunner
 *
 * @author 魏豆豆
 * @date 2021/4/4
 */
@Component
@Slf4j
public class BootApplicationRunner implements ApplicationRunner {
    @Override
    public void run(ApplicationArguments args) throws Exception {
      log.info("BootApplicationRunner===========启动");
    }
}

BootCommandRunner

package com.imooc.springboot.application.study;

import lombok.extern.slf4j.Slf4j;
import org.springframework.boot.CommandLineRunner;
import org.springframework.stereotype.Component;

/**
 * BootCommandRunner
 *
 * @author 魏豆豆
 * @date 2021/4/4
 */
@Component
@Slf4j
public class BootCommandRunner implements CommandLineRunner {
    @Override
    public void run(String... args) throws Exception {
        log.info("============================BootCommandRunner");
    }
}

打印日志

  .   ____          _            __ _ _
 /\ / ___'_ __ _ _(_)_ __  __ _    
( ( )\___ | '_ | '_| | '_ / _` |    
 \/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.1.4.RELEASE)

2021-04-04 08:39:37.971  INFO 32 --- [           main] c.i.s.a.SpringBootStudyApplication       : Starting SpringBootStudyApplication on DESKTOP-A08HONB with PID 32 (F:kewaiSpringCloudlaoqinchapter_3imooc_springboot_study	argetclasses started by weijingli in F:kewaiSpringCloudlaoqinchapter_3imooc_springboot_study)
2021-04-04 08:39:37.982  INFO 32 --- [           main] c.i.s.a.SpringBootStudyApplication       : No active profile set, falling back to default profiles: default
2021-04-04 08:39:43.845 ERROR 32 --- [           main] o.a.catalina.core.AprLifecycleListener   : An incompatible version [1.1.32] of the APR based Apache Tomcat Native library is installed, while Tomcat requires version [1.2.14]
2021-04-04 08:39:45.470 ERROR 32 --- [           main] o.a.catalina.core.AprLifecycleListener   : An incompatible version [1.1.32] of the APR based Apache Tomcat Native library is installed, while Tomcat requires version [1.2.14]
2021-04-04 08:39:45.828  INFO 32 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8081 (http)
2021-04-04 08:39:45.855 ERROR 32 --- [           main] o.a.catalina.core.AprLifecycleListener   : An incompatible version [1.1.32] of the APR based Apache Tomcat Native library is installed, while Tomcat requires version [1.2.14]
2021-04-04 08:39:45.871  INFO 32 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2021-04-04 08:39:45.871  INFO 32 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.17]
2021-04-04 08:39:46.403  INFO 32 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/imooc]  : Initializing Spring embedded WebApplicationContext
2021-04-04 08:39:46.403  INFO 32 --- [           main] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 8187 ms
2021-04-04 08:39:47.698  INFO 32 --- [           main] o.s.s.concurrent.ThreadPoolTaskExecutor  : Initializing ExecutorService 'applicationTaskExecutor'
2021-04-04 08:39:48.347  INFO 32 --- [           main] o.s.s.c.ThreadPoolTaskScheduler          : Initializing ExecutorService 'taskScheduler'
2021-04-04 08:39:48.385  INFO 32 --- [           main] o.s.b.a.e.web.EndpointLinksResolver      : Exposing 2 endpoint(s) beneath base path '/actuator'
2021-04-04 08:39:48.649  INFO 32 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8081 (http) with context path '/imooc'
2021-04-04 08:39:48.656  INFO 32 --- [           main] c.i.s.a.SpringBootStudyApplication       : Started SpringBootStudyApplication in 13.154 seconds (JVM running for 15.812)
2021-04-04 08:39:48.692  INFO 32 --- [           main] c.i.s.a.study.BootApplicationRunner      : BootApplicationRunner===========启动
2021-04-04 08:39:48.692  INFO 32 --- [           main] c.i.s.a.study.BootCommandRunner          : ============================BootCommandRunner

4.2　　@Order调整先后顺序

BootApplicationRunner

package com.imooc.springboot.application.study;

import lombok.extern.slf4j.Slf4j;
import org.springframework.boot.ApplicationArguments;
import org.springframework.boot.ApplicationRunner;
import org.springframework.stereotype.Component;

/**
 * BootApplicationRunner
 *
 * @author 魏豆豆
 * @date 2021/4/4
 */
@Order(2)
@Component
@Slf4j
public class BootApplicationRunner implements ApplicationRunner {
    @Override
    public void run(ApplicationArguments args) throws Exception {
      log.info("BootApplicationRunner===========启动");
    }
}

BootCommandRunner

package com.imooc.springboot.application.study;

import lombok.extern.slf4j.Slf4j;
import org.springframework.boot.CommandLineRunner;
import org.springframework.stereotype.Component;

/**
 * BootCommandRunner
 *
 * @author 魏豆豆
 * @date 2021/4/4
 */
@Order(1)
@Component
@Slf4j
public class BootCommandRunner implements CommandLineRunner {
    @Override
    public void run(String... args) throws Exception {
        log.info("============================BootCommandRunner");
    }
}

打印日志：

2021-04-04 08:46:11.492  INFO 18544 --- [           main] c.i.s.a.study.BootCommandRunner          : ============================BootCommandRunner
2021-04-04 08:46:11.492  INFO 18544 --- [           main] c.i.s.a.study.BootApplicationRunner      : BootApplicationRunner===========启动

诸葛