Spring Boot with a Custom Parent

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1. Overview

Spring Boot provides the parent POM for the easier creation of Spring Boot applications.

Not everyone likes inheriting from the spring-boot-starter-parent POM to create an executable jar/war. You may have your own corporate standard parent that you need to use, or you may just prefer to explicitly declare all your Maven configuration. In this tutorial, we’ll demonstrate how to create an executable jar/war using Maven without a parent pom.

2. Spring Boot Without Parent POM

We use Apache Maven to build and manage our project dependencies. This time we don’t inherit from the spring-boot-starter-parent but include a  dependencyManagement  BOM. When using this BOM, we need to include the  repackage  goal to create an executable jar/war file.

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>

	<groupId>com.dailycodebuffer.example</groupId>
	<artifactId>Spring-Boot-Custom-Parent</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>Spring-Boot-Custom-Parent</name>
	<description>Demo project for Spring Boot</description>

	<properties>
		<java.version>11</java.version>
	</properties>

	<dependencyManagement>
		<dependencies>
			<dependency>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-dependencies</artifactId>
				<version>2.2.0.RELEASE</version>
				<type>pom</type>
				<scope>import</scope>
			</dependency>
		</dependencies>
	</dependencyManagement>

	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
			<exclusions>
				<exclusion>
					<groupId>org.junit.vintage</groupId>
					<artifactId>junit-vintage-engine</artifactId>
				</exclusion>
			</exclusions>
		</dependency>
	</dependencies>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
				<configuration>
					<mainClass>com.dailycodebuffer.example.SpringBootCustomParen.SpringBootCustomParentApplication</mainClass>
				</configuration>
				<executions>
					<execution>
						<goals>
							<goal>repackage</goal>
						</goals>
					</execution>
				</executions>
			</plugin>
		</plugins>
	</build>

</project>

Next, we can start simply start adding Spring dependencies and making use of Spring Boot features:

<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-web</artifactId>
</dependency>

Bootstrapping Spring Boot

To illustrate this example, we created a simple class that’ll print some basic output to the console.

@SpringBootApplication
public class SpringBootCustomParentApplication {

	private static Logger log = LoggerFactory.getLogger(SpringBootCustomParentApplication.class);

	public static void main(String[] args) {
		SpringApplication.run(SpringBootCustomParentApplication.class, args);
	}

	@PostConstruct
	private void init(){
		log.info("creating an executable jar/war with spring boot without parent pom");
	}
}

Output

The previous application generates the following output.

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.2.0.RELEASE)

2019-11-02 00:59:11.383  INFO 7552 --- [           main] .d.e.S.SpringBootCustomParentApplication : Starting SpringBootCustomParentApplication on Shabbir with PID 7552 (E:\DailyCodeBuffer\Codes\Spring-MVC-Tutorials\Spring-Boot-Custom-Parent\target\classes started by shabb in E:\DailyCodeBuffer\Codes\Spring-MVC-Tutorials\Spring-Boot-Custom-Parent)
2019-11-02 00:59:11.431  INFO 7552 --- [           main] .d.e.S.SpringBootCustomParentApplication : No active profile set, falling back to default profiles: default
2019-11-02 00:59:15.580  INFO 7552 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2019-11-02 00:59:15.605  INFO 7552 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2019-11-02 00:59:15.606  INFO 7552 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.27]
2019-11-02 00:59:15.908  INFO 7552 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2019-11-02 00:59:15.908  INFO 7552 --- [           main] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 4107 ms
2019-11-02 00:59:16.019  INFO 7552 --- [           main] .d.e.S.SpringBootCustomParentApplication : creating an executable jar/war with spring boot without parent pom
2019-11-02 00:59:16.575  INFO 7552 --- [           main] o.s.s.concurrent.ThreadPoolTaskExecutor  : Initializing ExecutorService 'applicationTaskExecutor'
2019-11-02 00:59:17.029  INFO 7552 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
2019-11-02 00:59:17.042  INFO 7552 --- [           main] .d.e.S.SpringBootCustomParentApplication : Started SpringBootCustomParentApplication in 6.993 seconds (JVM running for 9.981)
2019-11-02 00:59:42.356  INFO 7552 --- [nio-8080-exec-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring DispatcherServlet 'dispatcherServlet'
2019-11-02 00:59:42.357  INFO 7552 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Initializing Servlet 'dispatcherServlet'
2019-11-02 00:59:42.382  INFO 7552 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Completed initialization in 25 ms

3. Conclusion

In this quick tutorial, we’ve seen how we can use Spring Boot without the parent pom.xml.

The source code for the examples can be found over on GitHub.

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