了解多模块项目中的 Spring Boot Maven 插件

Question

I'm learning about Spring Boot multi module projects and I try to understand what exactly does spring boot maven plugin.

For example I have 2 different projects. In the first project I have the spring boot maven plugin in the web module:

<build>
  <plugins>
    <plugin>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-maven-plugin</artifactId>
      <version>2.0.4.RELEASE</version>
      <configuration>
        <mainClass>dgs.web.DemoApplication</mainClass>
        <layout>ZIP</layout>
      </configuration>
      <executions>
        <execution>
          <goals>
            <goal>repackage</goal>
          </goals>
        </execution>
      </executions>
    </plugin>
  </plugins>
</build>

And in the second project I have this plugin in the data module:

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
         <executions>
             <execution>
                 <goals>
                     <goal>repackage</goal>
                 </goals>
                 <configuration>
                     <skip>true</skip>
                 </configuration>
             </execution>
         </executions>
        </plugin>
    </plugins>
</build>

And this is in the parent pom of the 2nd project:

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

Can somebody explain me what exaclty does this spring boot maven plugin especially in the second project? And why there is no reference about mainClass. I see this mainClass tag only in the first project.

Answer 1

The maven plugin is for packaging and executing via Maven.

You should read the docs:

https://docs.spring.io/spring-boot/docs/current/reference/html/build-tool-plugins-maven-plugin.html

https://docs.spring.io/spring-boot/docs/2.0.4.RELEASE/maven-plugin/