example of Multi-module maven with Spring Boot

Question

I want to know how i can create a multi module project with maven using Spring Boot.

Can someone show me an example of the "parent-pom" and "child-pom"?

Thanks

Answer 1

Modules as a spring boot project

Spring boot usually works with parent. But if you create multi module project and if you want to use spring boot on some of your module there is a important question, which one will be the parent? Of course your main project must be parent. So you should use spring boot as a dependency in your module.

<dependencyManagement>
     <dependencies>
        <dependency>
            <!-- Import dependency management from Spring Boot -->
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-dependencies</artifactId>
            <version>1.5.9.RELEASE</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

For detailed information please review following documentation;

https://docs.spring.io/spring-boot/docs/current/reference/html/using-boot-build-systems.html#using-boot-maven-without-a-parent

Answer 2

@juanhl it is so simple. You can create Multi-module maven project with Spring Boot.

Steps : 1)Create Maven project.The Parent project's pom.xml is like following,

    <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.springmultumoduleweb</groupId>
      <artifactId>multimodule-web-app</artifactId>
      <packaging>pom</packaging>

      <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.6.RELEASE</version>
      </parent> 
        <properties>
            <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
            <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
            <java.version>1.8</java.version>
        </properties>
      <modules>
        <module>multimodule-api</module>
        <module>multimodule-service</module>
        <module>EarModule</module>
      </modules>
      <version>0.0.1-SNAPSHOT</version>
    </project>

2) add maven module to the parent modules child modules may have one or more dependencies of other modules and packaging type may be jar or war.

3)create one more module to generate ear file.(packaging type : ear ) which contains dependencies of all modules as below,

<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>
  <parent>
    <groupId>com.springbootparent.demo</groupId>
    <artifactId>com.springbootparent.demo</artifactId>
    <version>0.0.1-SNAPSHOT</version
  </parent>
  <artifactId>com.springboot.ear</artifactId>
  <packaging>ear</packaging>
  <dependencies>
    <dependency>
        <groupId>com.springbootparent.demo</groupId>
        <artifactId>com.springboot.service1</artifactId>
        <version>0.0.1-SNAPSHOT</version>
    </dependency>
    <dependency>
        <groupId>com.springbootparent.demo</groupId>
        <artifactId>com.springboot.service2</artifactId>
        <version>0.0.1-SNAPSHOT</version>
    </dependency>
    <dependency>
        <groupId>com.springbootparent.demo</groupId>
        <artifactId>com.springboot.war1</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <type>war</type>
    </dependency>
    <dependency>
        <groupId>com.springbootparent.demo</groupId>
        <artifactId>com.springboot.war2</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <type>war</type>
    </dependency>
  </dependencies>
</project> 

4) clean and install maven parent project.

5) deploy created ear/war file on server. (for ear file you have to deploy on Enterprise Application server)

-Good luck

Answer 3

This question is too simple to answer or too complex to be understood, otherwise I cannot explain why there are no answers.

I would go for a solution that uses a folder structure like the following

project folder
|---pom.xml
|---module1
    |---pom.xml
    |---src
|---module2
    |---pom.xml
    |---src
|---module3
    |---pom.xml
    |---src

I would define the pom.xml of the project with a pom packaging, e.g.:

<?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>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.2.7-RELEASE</version>
        <relativePath/>
    </parent>

    <groupId>com.myproject</groupId>
    <artifactId>project</artifactId>
    <packaging>pom</packaging>
    <version>0.0.1-SNAPSHOT</version>

    <modules>
        <module>module1</module>
        <module>module2</module>
        <module>module3</module>
    </modules>

    <name>MySupercoolProject</name>
    <description>What else?</description>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>

    <dependencies>
      <!-- Put here dependencies shared by your project -->
    </dependencies>
</project>

As you see, the parent of your project will be a spring-boot-starter-parent.

Then, the pom.xml of one of your modules will be, for instance:

<?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>

    <parent>
        <groupId>com.myproject</groupId>
        <artifactId>project</artifactId>
        <version>0.0.1-SNAPSHOT</version>
    </parent>

    <groupId>com.myproject</groupId>
    <artifactId>module1</artifactId>
    <packaging>war</packaging>
    <version>0.0.1-SNAPSHOT</version>

    <name>Application</name>
    <description>SudenGut application</description>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <start-class>com.myproject.MyApplication</start-class>
        <java.version>1.8</java.version>
        <tomcat.version>8.0.24</tomcat.version>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!--- this will not be enough to provide a cool app :) -->
    </dependencies>

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

where the main application is MyApplication.java in package com.myproject of module1.

I would use the jar packaging for the other modules without a main application, unless you have other submodules (i.e., pom packaging again).