This guide will help you understand how Spring Boot Starter Parent helps with managing dependency versions, the java version used by project and the default configuration for plug-ins.
You will learn
- What is Spring Boot Starter Parent?
- What are the important features of Spring Boot Starter Parent?
- When do you use Spring Boot Starter Parent?
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Tools you will need
- Maven 3.1+ is your build tool
- Your favorite IDE. We use Eclipse.
- JDK 1.8+
What is Spring Boot Starter Parent?
All Spring Boot projects typically use spring-boot-starter-parent as the parent in pom.xml.
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.4.0.RELEASE</version>
</parent>
Parent Poms allow you to manage the following things for multiple child projects and modules:
- Configuration - Java Version and Other Properties
- Depedency Management - Version of dependencies
- Default Plugin Configuration
What is inside Spring Boot Starter Parent?
First of all - Spring Boot Starter Parent defines spring-boot-dependencies as the parent pom. It inherits dependency management from spring-boot-dependencies. Details in the next section.
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-dependencies</artifactId>
<version>1.4.0.RELEASE</version>
<relativePath>../../spring-boot-dependencies</relativePath>
</parent>
Default java version is 1.6. A project can override this by specifying a property <java.version>1.8</java.version> in the project pom. A few other settings related to encoding and source, target version are also set in the parent pom.
<java.version>1.6</java.version>
<resource.delimiter>@</resource.delimiter> <!-- delimiter that doesn't clash with Spring ${} placeholders -->
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<maven.compiler.source>${java.version}</maven.compiler.source>
<maven.compiler.target>${java.version}</maven.compiler.target>
Spring Boot Starter Parent specifies the default configuration for a host of plugins including maven-failsafe-plugin, maven-jar-plugin and maven-surefire-plugin.
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-failsafe-plugin</artifactId>
<executions>
<execution>
<goals>
<goal>integration-test</goal>
<goal>verify</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<configuration>
<archive>
<manifest>
<mainClass>${start-class}</mainClass>
<addDefaultImplementationEntries>true</addDefaultImplementationEntries>
</manifest>
</archive>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<configuration>
<includes>
<include>**/*Tests.java</include>
<include>**/*Test.java</include>
</includes>
<excludes>
<exclude>**/Abstract*.java</exclude>
</excludes>
</configuration>
</plugin>
What does Spring Boot Starter Parent inherit from spring-boot-dependencies?
Spring Boot Dependencies defines the default dependency management for all Spring Boot projects. If we would want to use a new version of a specific dependency, we can override the version by specifying a new property in the project pom. The extract below shows some of the important dependencies that are managed by Spring Boot Dependencies parent pom. Since Spring Boot Starter Parent inherit from spring-boot-dependencies, it shares all these characteristics as well.
<properties>
<activemq.version>5.13.4</activemq.version>
...
<ehcache.version>2.10.2.2.21</ehcache.version>
<ehcache3.version>3.1.1</ehcache3.version>
...
<h2.version>1.4.192</h2.version>
<hamcrest.version>1.3</hamcrest.version>
<hazelcast.version>3.6.4</hazelcast.version>
<hibernate.version>5.0.9.Final</hibernate.version>
<hibernate-validator.version>5.2.4.Final</hibernate-validator.version>
<hikaricp.version>2.4.7</hikaricp.version>
<hikaricp-java6.version>2.3.13</hikaricp-java6.version>
<hornetq.version>2.4.7.Final</hornetq.version>
<hsqldb.version>2.3.3</hsqldb.version>
<htmlunit.version>2.21</htmlunit.version>
<httpasyncclient.version>4.1.2</httpasyncclient.version>
<httpclient.version>4.5.2</httpclient.version>
<httpcore.version>4.4.5</httpcore.version>
<infinispan.version>8.2.2.Final</infinispan.version>
<jackson.version>2.8.1</jackson.version>
....
<jersey.version>2.23.1</jersey.version>
<jest.version>2.0.3</jest.version>
<jetty.version>9.3.11.v20160721</jetty.version>
<jetty-jsp.version>2.2.0.v201112011158</jetty-jsp.version>
<spring-security.version>4.1.1.RELEASE</spring-security.version>
<tomcat.version>8.5.4</tomcat.version>
<undertow.version>1.3.23.Final</undertow.version>
<velocity.version>1.7</velocity.version>
<velocity-tools.version>2.0</velocity-tools.version>
<webjars-hal-browser.version>9f96c74</webjars-hal-browser.version>
<webjars-locator.version>0.32</webjars-locator.version>
<wsdl4j.version>1.6.3</wsdl4j.version>
<xml-apis.version>1.4.01</xml-apis.version>
</properties>
Defines Maven 3.2.1 as the minimum version needed.
<prerequisites>
<maven>3.2.1</maven>
</prerequisites>