Executing Code on Startup of Spring Boot Application

In this tutorial, we will find how to execute a block of code on application startup.

Developers frequently need some startup code that needs to be executed once the application starts. This can be reading a set of configuration values from the database which will remain constant or execute some notification logic. Spring boot provides ApplicationRunner and CommandLineRunner interfaces to accomplish this task. 

Spring boot also provides ApplicationArguments class which can be injected into any class that needs program argument values.

Find this project on Github

https://github.com/javacodenet/spring-boot-application-startup-code

pom.xml

	<?xml version="1.0" encoding="UTF-8"?>
	<project xmlns="http://maven.apache.org/POM/4.0.0"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.javacodenet</groupId>
	<artifactId>spring-boot</artifactId>
	<version>1.0-SNAPSHOT</version>
	<parent>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-parent</artifactId>
	<version>1.4.0.RELEASE</version>
	</parent>
	<dependencies>
	<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-web</artifactId>
	</dependency>
	</dependencies>
	<build>
	<plugins>
	<plugin>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-maven-plugin</artifactId>
	</plugin>
	</plugins>
	</build>
	</project>

view raw pom.xml hosted with ❤ by GitHub

Application.java

	package com.javacodenet;
	import org.springframework.beans.factory.annotation.Autowired;
	import org.springframework.beans.factory.annotation.Value;
	import org.springframework.boot.ApplicationArguments;
	import org.springframework.boot.SpringApplication;
	import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
	import org.springframework.boot.autoconfigure.SpringBootApplication;
	import org.springframework.boot.context.properties.EnableConfigurationProperties;
	import org.springframework.web.bind.annotation.RequestMapping;
	import org.springframework.web.bind.annotation.RestController;
	@RestController
	@SpringBootApplication
	public class Application {
	@Autowired
	ApplicationArguments applicationArguments;
	@RequestMapping("/")
	public String programArguments() {
	String output = "Application Startup Program arguments:";
	for (String arg: applicationArguments.getOptionNames()) {
	output = output + " " + arg;
	}
	return output;
	}
	public static void main(String[] args) {
	SpringApplication.run(Application.class, args);
	}
	}

view raw Application.java hosted with ❤ by GitHub

MyCommandLineRunner.java

	package com.javacodenet;
	import org.springframework.boot.CommandLineRunner;
	import org.springframework.stereotype.Component;
	@Component
	public class MyCommandLineRunner implements CommandLineRunner{
	@Override
	public void run(String... args) throws Exception {
	System.out.println("Application Startup Program arguments");
	for (String arg: args) {
	System.out.println(arg);
	}
	}
	}

view raw MyCommandLineRunner.java hosted with ❤ by GitHub

MyApplicationRunner.java

	package com.javacodenet;
	import org.springframework.boot.ApplicationArguments;
	import org.springframework.boot.ApplicationRunner;
	import org.springframework.stereotype.Component;
	@Component
	public class MyApplicationRunner implements ApplicationRunner{
	@Override
	public void run(ApplicationArguments args) throws Exception {
	System.out.println("Application Startup Program arguments");
	for (String arg: args.getOptionNames()) {
	System.out.println(arg);
	}
	}
	}

view raw MyApplicationRunner.java hosted with ❤ by GitHub

Program arguments added

Output from MyCommandLineRunner

Output from MyApplicationRunner

Rest End Point Output