Spring Boot - 執行器

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Application Runner 和 Command Line Runner 介面允許您在 Spring Boot 應用程式啟動後執行程式碼。您可以使用這些介面在應用程式啟動後立即執行任何操作。本章詳細介紹了它們。

Application Runner

Application Runner 是一個用於在 Spring Boot 應用程式啟動後執行程式碼的介面。下面的示例顯示瞭如何在主類檔案上實現 Application Runner 介面。

DemoApplication.java

package com.tutorialspoint.demo;

import org.springframework.boot.ApplicationArguments;
import org.springframework.boot.ApplicationRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class DemoApplication implements ApplicationRunner {
   public static void main(String[] args) {
      SpringApplication.run(DemoApplication.class, args);
   }
   @Override
   public void run(ApplicationArguments arg0) throws Exception {
      System.out.println("Hello World from Application Runner");
   }
}

控制檯輸出

現在，如果您觀察下面的控制檯視窗輸出Hello World from Application Runner，則 println 語句在 Tomcat 啟動後執行。

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/

[32m :: Spring Boot :: [39m              [2m (v3.3.3)[0;39m

[2m2024-09-04T12:05:41.902+05:30[0;39m [32m INFO[0;39m [35m12304[0;39m [2m---[0;39m [2m[demo] [           main][0;39m [2m[0;39m[36mc.tutorialspoint.demo.DemoApplication   [0;39m [2m:[0;39m Starting DemoApplication using Java 21.0.3 with PID 12304 (E:\Dev\demo\target\classes started by Tutorialspoint in E:\Dev\demo)
[2m2024-09-04T12:05:41.905+05:30[0;39m [32m INFO[0;39m [35m12304[0;39m [2m---[0;39m [2m[demo] [           main][0;39m [2m[0;39m[36mc.tutorialspoint.demo.DemoApplication   [0;39m [2m:[0;39m No active profile set, falling back to 1 default profile: "default"
[2m2024-09-04T12:05:43.427+05:30[0;39m [32m INFO[0;39m [35m12304[0;39m [2m---[0;39m [2m[demo] [           main][0;39m [2m[0;39m[36mo.s.b.w.embedded.tomcat.TomcatWebServer [0;39m [2m:[0;39m Tomcat initialized with port 8080 (http)
[2m2024-09-04T12:05:43.454+05:30[0;39m [32m INFO[0;39m [35m12304[0;39m [2m---[0;39m [2m[demo] [           main][0;39m [2m[0;39m[36mo.apache.catalina.core.StandardService  [0;39m [2m:[0;39m Starting service [Tomcat]
[2m2024-09-04T12:05:43.454+05:30[0;39m [32m INFO[0;39m [35m12304[0;39m [2m---[0;39m [2m[demo] [           main][0;39m [2m[0;39m[36mo.apache.catalina.core.StandardEngine   [0;39m [2m:[0;39m Starting Servlet engine: [Apache Tomcat/10.1.28]
[2m2024-09-04T12:05:43.528+05:30[0;39m [32m INFO[0;39m [35m12304[0;39m [2m---[0;39m [2m[demo] [           main][0;39m [2m[0;39m[36mo.a.c.c.C.[Tomcat].[localhost].[/]      [0;39m [2m:[0;39m Initializing Spring embedded WebApplicationContext
[2m2024-09-04T12:05:43.529+05:30[0;39m [32m INFO[0;39m [35m12304[0;39m [2m---[0;39m [2m[demo] [           main][0;39m [2m[0;39m[36mw.s.c.ServletWebServerApplicationContext[0;39m [2m:[0;39m Root WebApplicationContext: initialization completed in 1552 ms
[2m2024-09-04T12:05:44.120+05:30[0;39m [32m INFO[0;39m [35m12304[0;39m [2m---[0;39m [2m[demo] [           main][0;39m [2m[0;39m[36mo.s.b.w.embedded.tomcat.TomcatWebServer [0;39m [2m:[0;39m Tomcat started on port 8080 (http) with context path '/'
[2m2024-09-04T12:05:44.134+05:30[0;39m [32m INFO[0;39m [35m12304[0;39m [2m---[0;39m [2m[demo] [           main][0;39m [2m[0;39m[36mc.tutorialspoint.demo.DemoApplication   [0;39m [2m:[0;39m Started DemoApplication in 3.007 seconds (process running for 4.519)
Hello World from Application Runner

Command Line Runner

Command Line Runner 是一個介面。它用於在 Spring Boot 應用程式啟動後執行程式碼。下面的示例顯示瞭如何在主類檔案上實現 Command Line Runner 介面。

DemoApplication.java

package com.tutorialspoint.demo;

import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class DemoApplication implements CommandLineRunner {
   public static void main(String[] args) {
      SpringApplication.run(DemoApplication.class, args);
   }
   @Override
   public void run(String... arg0) throws Exception {
      System.out.println("Hello world from Command Line Runner");
   }
}

控制檯輸出

檢視下面的控制檯視窗輸出“Hello world from Command Line Runner” println 語句在 Tomcat 啟動後執行。

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/

[32m :: Spring Boot :: [39m              [2m (v3.3.3)[0;39m

[2m2024-09-04T12:08:37.804+05:30[0;39m [32m INFO[0;39m [35m16908[0;39m [2m---[0;39m [2m[demo] [           main][0;39m [2m[0;39m[36mc.tutorialspoint.demo.DemoApplication   [0;39m [2m:[0;39m Starting DemoApplication using Java 21.0.3 with PID 16908 (E:\Dev\demo\target\classes started by Tutorialspoint in E:\Dev\demo)
[2m2024-09-04T12:08:37.808+05:30[0;39m [32m INFO[0;39m [35m16908[0;39m [2m---[0;39m [2m[demo] [           main][0;39m [2m[0;39m[36mc.tutorialspoint.demo.DemoApplication   [0;39m [2m:[0;39m No active profile set, falling back to 1 default profile: "default"
[2m2024-09-04T12:08:38.772+05:30[0;39m [32m INFO[0;39m [35m16908[0;39m [2m---[0;39m [2m[demo] [           main][0;39m [2m[0;39m[36mo.s.b.w.embedded.tomcat.TomcatWebServer [0;39m [2m:[0;39m Tomcat initialized with port 8080 (http)
[2m2024-09-04T12:08:38.786+05:30[0;39m [32m INFO[0;39m [35m16908[0;39m [2m---[0;39m [2m[demo] [           main][0;39m [2m[0;39m[36mo.apache.catalina.core.StandardService  [0;39m [2m:[0;39m Starting service [Tomcat]
[2m2024-09-04T12:08:38.786+05:30[0;39m [32m INFO[0;39m [35m16908[0;39m [2m---[0;39m [2m[demo] [           main][0;39m [2m[0;39m[36mo.apache.catalina.core.StandardEngine   [0;39m [2m:[0;39m Starting Servlet engine: [Apache Tomcat/10.1.28]
[2m2024-09-04T12:08:38.841+05:30[0;39m [32m INFO[0;39m [35m16908[0;39m [2m---[0;39m [2m[demo] [           main][0;39m [2m[0;39m[36mo.a.c.c.C.[Tomcat].[localhost].[/]      [0;39m [2m:[0;39m Initializing Spring embedded WebApplicationContext
[2m2024-09-04T12:08:38.842+05:30[0;39m [32m INFO[0;39m [35m16908[0;39m [2m---[0;39m [2m[demo] [           main][0;39m [2m[0;39m[36mw.s.c.ServletWebServerApplicationContext[0;39m [2m:[0;39m Root WebApplicationContext: initialization completed in 980 ms
[2m2024-09-04T12:08:39.185+05:30[0;39m [32m INFO[0;39m [35m16908[0;39m [2m---[0;39m [2m[demo] [           main][0;39m [2m[0;39m[36mo.s.b.w.embedded.tomcat.TomcatWebServer [0;39m [2m:[0;39m Tomcat started on port 8080 (http) with context path '/'
[2m2024-09-04T12:08:39.192+05:30[0;39m [32m INFO[0;39m [35m16908[0;39m [2m---[0;39m [2m[demo] [           main][0;39m [2m[0;39m[36mc.tutorialspoint.demo.DemoApplication   [0;39m [2m:[0;39m Started DemoApplication in 1.844 seconds (process running for 2.693)
Hello world from Command Line Runner
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