Comprehensive Maven Guide: Repository Setup, Dependency Management, Multi‑Module Projects, and Plugin Configuration

1. Basic Configuration

Maven introduces the concept of repositories; developers publish JARs to a remote repository and Maven downloads them to the local repository when referenced, optionally using a private repository before falling back to the central one.

A minimal Maven project includes groupId, artifactId, and version elements.

<?xml version="1.0" encoding="UTF-8"?>
<project ...>
    <!-- fixed 4.0.0, specifies the POM model version -->
    <modelVersion>4.0.0</modelVersion>
    <groupId>xyz.ibudai</groupId>
    <artifactId>maven-demo</artifactId>
    <version>1.0.0‑SNAPSHOT</version>
    <description>This is maven demo.</description>
</project>

2. Dependency Management

2.1 Dependency Introduction

Dependencies are added via the dependencies tag.

<dependencies>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql‑connector‑java</artifactId>
        <version>8.0.27</version>
        <scope>runtime</scope>
    </dependency>
</dependencies>

The scope element can be compile, provided, runtime, test, or system.

2.2 Transitive Dependencies

Maven resolves transitive dependencies automatically; only the direct dependency needs to be declared.

2.3 Dependency Exclusion

Conflicting versions can be excluded using the excludes tag.

<dependency>
    <groupId>xyz.ibudai</groupId>
    <artifactId>demo‑a</artifactId>
    <version>1.0.0</version>
    <excludes>
        <exclude>
            <groupId>xyz.ibudai</groupId>
            <artifactId>dependency‑b</artifactId>
            <version>1.0.0</version>
        </exclude>
    </excludes>
</dependency>

2.4 Variable Configuration

Version numbers can be centralized with properties and referenced via ${}.

<properties>
    <mysql.version>8.0.30</mysql.version>
    <junit.version>4.13.2</junit.version>
</properties>

<dependencies>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql‑connector‑java</artifactId>
        <version>${mysql.version}</version>
    </dependency>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>${junit.version}</version>
    </dependency>
</dependencies>

3. Module Configuration

Multi‑module projects use the modules tag in the parent POM.

<modules>
    <module>module‑1</module>
    <module>module‑2</module>
</modules>

Child modules inherit groupId, artifactId, and version from the parent via the parent element.

4. Unified Dependency Management

Common dependencies are declared once in the parent’s dependencyManagement section and inherited by child modules.

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql‑connector‑java</artifactId>
            <version>8.0.30</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13.2</version>
        </dependency>
    </dependencies>
</dependencyManagement>

5. Plugin Management

5.1 Maven‑Jar‑Plugin

Customizes the JAR manifest.

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven‑jar‑plugin</artifactId>
    <version>2.3.1</version>
    <configuration>
        <archive>
            <manifest>
                <mainClass>org.example.MyTest</mainClass>
                <addDefaultSpecificationEntries>true</addDefaultSpecificationEntries>
                <addDefaultImplementationEntries>true</addDefaultImplementationEntries>
                <manifestEntries>
                    <Plugin‑Id>demo‑plugin</Plugin‑Id>
                    <Plugin‑Version>1.0.0</Plugin‑Version>
                </manifestEntries>
            </manifest>
        </archive>
    </configuration>
</plugin>

5.2 Maven‑Assembly‑Plugin

Packages all project classes together with their dependencies.

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven‑assembly‑plugin</artifactId>
    <version>3.1.0</version>
    <configuration>
        <descriptorRefs>
            <descriptorRef>jar‑with‑dependencies</descriptorRef>
        </descriptorRefs>
        <finalName>${project.artifactId}-${project.version}-all</finalName>
        <appendAssemblyId>false</appendAssemblyId>
        <attach>false</attach>
    </configuration>
    <executions>
        <execution>
            <id>make‑assembly</id>
            <phase>package</phase>
            <goals>
                <goal>single</goal>
            </goals>
        </execution>
    </executions>
</plugin>

5.3 Maven‑Shade‑Plugin

Creates an uber‑JAR with optional class relocation and selective inclusion.

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven‑shade‑plugin</artifactId>
    <version>3.2.0</version>
    <executions>
        <execution>
            <phase>package</phase>
            <goals>
                <goal>shade</goal>
            </goals>
        </execution>
    </executions>
    <configuration>
        <minimizeJar>true</minimizeJar>
        <artifactSet>
            <includes>
                <include>com.fasterxml.jackson.core:jackson‑core</include>
            </includes>
        </artifactSet>
        <relocations>
            <relocation>
                <pattern>com.fasterxml.jackson.core</pattern>
                <shadedPattern>com.ibudai.fasterxml.jackson.core</shadedPattern>
            </relocation>
        </relocations>
        <filters>
            <filter>
                <artifact>*:*</artifact>
                <excludes>
                    <exclude>META‑INF/license/**</exclude>
                    <exclude>META‑INF/*</exclude>
                    <exclude>LICENSE</exclude>
                    <exclude>NOTICE</exclude>
                </excludes>
            </filter>
        </filters>
    </configuration>
</plugin>

6. Build Configuration

6.1 JDK Version

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven‑compiler‑plugin</artifactId>
    <version>3.1</version>
    <configuration>
        <source>8</source>
        <target>8</target>
    </configuration>
</plugin>

6.2 Resource Exclusion

<resources>
    <resource>
        <directory>src/main/resources</directory>
        <excludes>
            <exclude>application.yml</exclude>
        </excludes>
    </resource>
</resources>

6.3 Main Class Specification

<plugin>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring‑boot‑maven‑plugin</artifactId>
    <configuration>
        <mainClass>xyz.ibudai.TestWebApplication</mainClass>
        <layout>JAR</layout>
    </configuration>
</plugin>

By following these configurations, developers can efficiently manage dependencies, avoid version conflicts, build modular Maven projects, and produce executable JARs with the desired metadata and bundled libraries.