具有同级项目依赖项的多模块Maven Spring启动项目

Question

I'm trying to create a multi-module maven Spring Boot project. My project hierarchy is as follows:

Parent-Project: (packaging type: pom)
  |
  |==> Commons-Project (packaging type: jar)
  |==> Child-Project (packaging type: jar | Has Commons-Project dependency)

When I try to compile the parent project, it successfully compiles the Parent-Project and Commons-Project. However, the build for Child-Project fails!

Following is the code:

<?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>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.8.RELEASE</version>
        <relativePath /> <!-- lookup parent from repository -->
    </parent>

    <groupId>com.example</groupId>
    <artifactId>parent</artifactId>
    <version>1.1.0</version>

    <name>parent</name>
    <packaging>pom</packaging>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
        <commons.version>1.0</commons.version>
    </properties>

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

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

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>com.example</groupId>
                <artifactId>commons</artifactId>
                <version>${commons.version}</version>
            </dependency>
        </dependencies>
    </dependencyManagement>

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

    <modules>
        <module>commons</module>
        <module>child</module>
    </modules>
</project>

<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.example</groupId>
        <artifactId>parent</artifactId>
        <version>1.1.0</version>
    </parent>

    <artifactId>commons</artifactId>
    <version>1.0</version>
    <packaging>pom</packaging>
</project>

package commons.utils;

public class CommonUtility {
    //Common Utility methods go here
}

<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.example</groupId>
        <artifactId>parent</artifactId>
        <version>1.1.0</version>
    </parent>

    <artifactId>child</artifactId>
    <version>1.0</version>

    <dependencies>
        <dependency>
            <groupId>com.example</groupId>
            <artifactId>commons</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>
</project>

package child;

import javax.annotation.PostConstruct;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

import commons.utils.CommonUtility;

@SpringBootApplication
public class ChildApplication {
    public static void main(String[] args) throws Exception {
        SpringApplication.run(ChildApplication.class, args);
    }

    @PostConstruct
    public void init() {
        // For test
        System.out.println(CommonUtility.class.getName());
    }
}

When I run the Child's Main class in STS, everything works fine. But when I try to run mvn clean package or mvn clean install , the build fails with the message:

Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.8.1:compile (default-compile) on project child: Compilation failure: Compilation failure:
...
package commons.utils does not exist

I'm not sure, what wrong am I doing?

I have uploaded this project on GitHub , just in case someone wants to have a look at the code. If anyone is able to find a solution. Please let me know.

Answer 1

Please try with the following changes.

Add the below in Commons pom.

<groupId>commons</groupId>

Finally the common pom.xml looks like the 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.example</groupId>
        <artifactId>parent</artifactId>
        <version>0.0.1-SNAPSHOT</version>
    </parent>
    <groupId>commons</groupId>
    <artifactId>commons</artifactId>
</project>

Now add the below in child pom.xml.

<groupId>commons</groupId>

Finally child pom.xml looks like this.

<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.example</groupId>
        <artifactId>parent</artifactId>
        <version>0.0.1-SNAPSHOT</version>
    </parent>

    <artifactId>child</artifactId>

    <dependencies>
        <dependency>
            <groupId>commons</groupId>
            <artifactId>commons</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </dependency>
    </dependencies>
</project>

Answer 2

Try updating the poms as below. Complete example is uploaded on GitHub

parent pom:

<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>

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.1.8.RELEASE</version>
    <relativePath /> <!-- lookup parent from repository -->
</parent>

<groupId>com.example</groupId>
<artifactId>parent</artifactId>
<version>1.1.0</version>

<name>parent</name>
<packaging>pom</packaging>
<description>Demo project for Spring Boot</description>

<properties>
    <java.version>1.8</java.version>
    <commons.version>1.0</commons.version>
</properties>

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

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
</dependencies>
</dependencyManagement>

<modules>
    <module>commons</module>
    <module>child</module>
</modules>

commons pom:

<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.example</groupId>
<artifactId>commons</artifactId>
<packaging>jar</packaging>

<parent>
    <groupId>com.example</groupId>
    <artifactId>parent</artifactId>
    <version>1.1.0</version>
</parent>

child pom:

<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.example</groupId>
<artifactId>child</artifactId>
<packaging>jar</packaging>

<parent>
    <groupId>com.example</groupId>
    <artifactId>parent</artifactId>
    <version>1.1.0</version>
</parent>

<dependencies>
    <dependency>
        <groupId>com.example</groupId>
        <artifactId>commons</artifactId>
        <version>${project.version}</version>
    </dependency>
    <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>