springboot(十五)-Runner启动器

Runner启动器

如果你想在Spring Boot启动的时候运行一些特定的代码，你可以实现接口ApplicationRunner或者CommandLineRunner，这两个接口实现方式一样，它们都只提供了一个run方法。

CommandLineRunner：启动获取命令行参数。

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;

}

ApplicationRunner：启动获取应用启动的时候参数。

public interface ApplicationRunner {

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

}

使用方式

import org.springframework.boot.*;
import org.springframework.context.annotation.Bean;
import org.springframework.stereotype.*;

@Component
public class MyBean implements CommandLineRunner  {

    public void run(String... args) {
       System.out.println("haha");
    }
    
    @Bean
    public CommandLineRunner init() {

        return (String... strings) -> {
        System.out.println("enen");
        };

    }


}

提供两个方法，一个实现了接口提供的方法，一个自己定义一个Bean。我们看下效果。

05-09 18:10:07.920 INFO  [com.cetc.cks.Application] - Starting Application on LAPTOP-3HL6RUMK with PID 3012 (D:\workspaces\pro_cks_manager\target\classes started by 18811 in D:\workspaces\pro_cks_manager)
05-09 18:10:07.920 INFO  [com.cetc.cks.Application] - No active profile set, falling back to default profiles: default
05-09 18:10:08.436 INFO  [org.apache.catalina.core.StandardService] - Starting service [Tomcat]
05-09 18:10:08.436 INFO  [org.apache.catalina.core.StandardEngine] - Starting Servlet Engine: Apache Tomcat/8.5.23
05-09 18:10:08.498 INFO  [org.apache.jasper.servlet.TldScanner] - At least one JAR was scanned for TLDs yet contained no TLDs. Enable debug logging for this logger for a complete list of JARs that were scanned but no TLDs were found in them. Skipping unneeded JARs during scanning can improve startup time and JSP compilation time.
05-09 18:10:08.498 INFO  [o.a.c.core.ContainerBase.[Tomcat].[localhost].[/]] - Initializing Spring embedded WebApplicationContext
05-09 18:10:08.764 INFO  [org.hibernate.jpa.internal.util.LogHelper] - HHH000204: Processing PersistenceUnitInfo [
    name: default
    ...]
05-09 18:10:08.795 INFO  [org.hibernate.dialect.Dialect] - HHH000400: Using dialect: org.hibernate.dialect.MySQL5Dialect
haha
enen
05-09 18:10:09.025 INFO  [com.cetc.cks.Application] - Started Application in 1.148 seconds (JVM running for 414.131)

由控制台的log可知，都执行了。

我们实现另一个：

@Component
public class MyBean implements ApplicationRunner   {

//    public void run(String... args) {
//       System.out.println("haha");
//    }
    
    @Bean
    public CommandLineRunner init() {

        return (String... strings) -> {
        System.out.println("enen");
        };

    }

    @Override
    public void run(ApplicationArguments args) throws Exception {
        // TODO Auto-generated method stub
        System.out.println("666");
    }

}

同样，我们提供两个方法，一个实现接口的方法，还有一个自定义一个Bean。

05-09 18:12:58.234 INFO  [com.cetc.cks.Application] - Starting Application on LAPTOP-3HL6RUMK with PID 3012 (D:\workspaces\pro_cks_manager\target\classes started by 18811 in D:\workspaces\pro_cks_manager)
05-09 18:12:58.234 INFO  [com.cetc.cks.Application] - No active profile set, falling back to default profiles: default
05-09 18:12:58.703 INFO  [org.apache.catalina.core.StandardService] - Starting service [Tomcat]
05-09 18:12:58.703 INFO  [org.apache.catalina.core.StandardEngine] - Starting Servlet Engine: Apache Tomcat/8.5.23
05-09 18:12:58.766 INFO  [org.apache.jasper.servlet.TldScanner] - At least one JAR was scanned for TLDs yet contained no TLDs. Enable debug logging for this logger for a complete list of JARs that were scanned but no TLDs were found in them. Skipping unneeded JARs during scanning can improve startup time and JSP compilation time.
05-09 18:12:58.781 INFO  [o.a.c.core.ContainerBase.[Tomcat].[localhost].[/]] - Initializing Spring embedded WebApplicationContext
05-09 18:12:59.109 INFO  [org.hibernate.jpa.internal.util.LogHelper] - HHH000204: Processing PersistenceUnitInfo [
    name: default
    ...]
05-09 18:12:59.125 INFO  [org.hibernate.dialect.Dialect] - HHH000400: Using dialect: org.hibernate.dialect.MySQL5Dialect
666
enen
05-09 18:12:59.390 INFO  [com.cetc.cks.Application] - Started Application in 1.212 seconds (JVM running for 584.496)

由控制台的log可知，都执行了。而且都是先执行重写接口的方法。