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Java Maven Dependency and Build Helper Skill

java-maven-helper

Maven build system, dependency management, and Java project configuration assistance.

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SKILL.md

Full skill instructions

Java Maven Dependency and Build Helper Skill

Maven build system, dependency management, and Java project configuration assistance.

Instructions

You are a Maven and Java ecosystem expert. When invoked:

  1. Maven Project Management:

    • Initialize and configure Maven projects
    • Manage pom.xml configuration
    • Handle project structure and organization
    • Configure multi-module projects
    • Use Maven archetypes

  2. Dependency Management:

    • Add, update, and remove dependencies
    • Manage dependency scopes
    • Handle version conflicts
    • Use dependency management sections
    • Work with BOMs (Bill of Materials)

  3. Build Configuration:

    • Configure plugins and goals
    • Set up build profiles
    • Manage build lifecycle
    • Configure properties and resources
    • Handle filtering and resource processing

  4. Troubleshooting:

    • Fix dependency resolution errors
    • Debug build failures
    • Resolve plugin conflicts
    • Clean corrupted repositories
    • Handle version conflicts

  5. Best Practices: Provide guidance on Maven project organization, dependency management, and build optimization

Maven Basics

Project Initialization

# Create from archetype (interactive)
mvn archetype:generate

# Create quickstart project (non-interactive)
mvn archetype:generate \
  -DgroupId=com.example \
  -DartifactId=my-app \
  -DarchetypeArtifactId=maven-archetype-quickstart \
  -DarchetypeVersion=1.4 \
  -DinteractiveMode=false

# Create web application
mvn archetype:generate \
  -DgroupId=com.example \
  -DartifactId=my-webapp \
  -DarchetypeArtifactId=maven-archetype-webapp \
  -DinteractiveMode=false

# Create Spring Boot application
mvn archetype:generate \
  -DgroupId=com.example \
  -DartifactId=my-spring-app \
  -DarchetypeArtifactId=maven-archetype-quickstart \
  -DinteractiveMode=false

Basic Commands

# Clean build artifacts
mvn clean

# Compile project
mvn compile

# Run tests
mvn test

# Package (create JAR/​WAR)
mvn package

# Install to local repository
mvn install

# Deploy to remote repository
mvn deploy

# Skip tests
mvn package -DskipTests

# Run specific test
mvn test -Dtest=MyTest

# Show dependency tree
mvn dependency:tree

# Show effective POM
mvn help:effective-pom

# Run project (with exec plugin)
mvn exec:java -Dexec.mainClass="com.example.Main"

Usage Examples

@java-maven-helper
@java-maven-helper --init-project
@java-maven-helper --add-dependency
@java-maven-helper --fix-dependencies
@java-maven-helper --multi-module
@java-maven-helper --troubleshoot

pom.xml Configuration

Complete Example

<?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>

    <!-- Project Coordinates -->
    <groupId>com.example</​groupId>
    <artifactId>my-application</​artifactId>
    <version>1.0.0-SNAPSHOT</​version>
    <packaging>jar</​packaging>

    <!-- Project Information -->
    <name>My Application</​name>
    <description>A sample Maven project</​description>
    <url>https://github.com/user/my-application</​url>
    <inceptionYear>2024</​inceptionYear>

    <!-- Organization -->
    <organization>
        <name>Example Corp</​name>
        <url>https://example.com</​url>
    </​organization>

    <!-- Licenses -->
    <licenses>
        <license>
            <name>Apache License, Version 2.0</​name>
            <url>https://www.apache.org/licenses/LICENSE-2.0</​url>
            <distribution>repo</​distribution>
        </​license>
    </​licenses>

    <!-- Developers -->
    <developers>
        <developer>
            <id>dev1</​id>
            <name>Developer Name</​name>
            <email>[email protected]</​email>
            <organization>Example Corp</​organization>
            <roles>
                <role>developer</​role>
            </​roles>
        </​developer>
    </​developers>

    <!-- SCM -->
    <scm>
        <connection>scm:git:git://github.com/​user/​my-application.git</​connection>
        <developerConnection>scm:git:ssh://github.com/​user/​my-application.git</​developerConnection>
        <url>https://github.com/user/my-application</​url>
        <tag>HEAD</​tag>
    </​scm>

    <!-- Properties -->
    <properties>
        <!-- Java Version -->
        <maven.compiler.source>17</​maven.compiler.source>
        <maven.compiler.target>17</​maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</​project.build.sourceEncoding>

        <!-- Dependency Versions -->
        <spring.boot.version>3.2.0</​spring.boot.version>
        <junit.version>5.10.1</​junit.version>
        <lombok.version>1.18.30</​lombok.version>
        <slf4j.version>2.0.9</​slf4j.version>

        <!-- Plugin Versions -->
        <maven.compiler.plugin.version>3.11.0</​maven.compiler.plugin.version>
        <maven.surefire.plugin.version>3.2.2</​maven.surefire.plugin.version>
    </​properties>

    <!-- Dependency Management -->
    <dependencyManagement>
        <dependencies>
            <!-- Spring Boot BOM -->
            <dependency>
                <groupId>org.springframework.boot</​groupId>
                <artifactId>spring-boot-dependencies</​artifactId>
                <version>${spring.boot.version}</​version>
                <type>pom</​type>
                <scope>import</​scope>
            </​dependency>
        </​dependencies>
    </​dependencyManagement>

    <!-- Dependencies -->
    <dependencies>
        <!-- Spring Boot Starter -->
        <dependency>
            <groupId>org.springframework.boot</​groupId>
            <artifactId>spring-boot-starter-web</​artifactId>
        </​dependency>

        <!-- Lombok -->
        <dependency>
            <groupId>org.projectlombok</​groupId>
            <artifactId>lombok</​artifactId>
            <version>${lombok.version}</​version>
            <scope>provided</​scope>
        </​dependency>

        <!-- Logging -->
        <dependency>
            <groupId>org.slf4j</​groupId>
            <artifactId>slf4j-api</​artifactId>
            <version>${slf4j.version}</​version>
        </​dependency>

        <!-- Test Dependencies -->
        <dependency>
            <groupId>org.junit.jupiter</​groupId>
            <artifactId>junit-jupiter</​artifactId>
            <version>${junit.version}</​version>
            <scope>test</​scope>
        </​dependency>

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

    <!-- Build Configuration -->
    <build>
        <!-- Final artifact name -->
        <finalName>${project.artifactId}</​finalName>

        <!-- Resources -->
        <resources>
            <resource>
                <directory>src/​main/​resources</​directory>
                <filtering>true</​filtering>
            </​resource>
        </​resources>

        <!-- Plugins -->
        <plugins>
            <!-- Compiler Plugin -->
            <plugin>
                <groupId>org.apache.maven.plugins</​groupId>
                <artifactId>maven-compiler-plugin</​artifactId>
                <version>${maven.compiler.plugin.version}</​version>
                <configuration>
                    <source>${maven.compiler.source}</​source>
                    <target>${maven.compiler.target}</​target>
                </​configuration>
            </​plugin>

            <!-- Surefire Plugin (Tests) -->
            <plugin>
                <groupId>org.apache.maven.plugins</​groupId>
                <artifactId>maven-surefire-plugin</​artifactId>
                <version>${maven.surefire.plugin.version}</​version>
            </​plugin>

            <!-- Spring Boot Plugin -->
            <plugin>
                <groupId>org.springframework.boot</​groupId>
                <artifactId>spring-boot-maven-plugin</​artifactId>
                <version>${spring.boot.version}</​version>
                <executions>
                    <execution>
                        <goals>
                            <goal>repackage</​goal>
                        </​goals>
                    </​execution>
                </​executions>
            </​plugin>
        </​plugins>
    </​build>

    <!-- Profiles -->
    <profiles>
        <profile>
            <id>development</​id>
            <activation>
                <activeByDefault>true</​activeByDefault>
            </​activation>
            <properties>
                <spring.profiles.active>dev</​spring.profiles.active>
            </​properties>
        </​profile>

        <profile>
            <id>production</​id>
            <properties>
                <spring.profiles.active>prod</​spring.profiles.active>
            </​properties>
        </​profile>
    </​profiles>

    <!-- Repositories -->
    <repositories>
        <repository>
            <id>central</​id>
            <name>Maven Central</​name>
            <url>https://repo.maven.apache.org/maven2</​url>
        </​repository>
    </​repositories>
</​project>

Dependency Scopes

<dependencies>
    <!-- Compile (default): Available in all classpaths -->
    <dependency>
        <groupId>org.apache.commons</​groupId>
        <artifactId>commons-lang3</​artifactId>
        <version>3.14.0</​version>
        <scope>compile</​scope>
    </​dependency>

    <!-- Provided: Available at compile time, not packaged -->
    <dependency>
        <groupId>javax.servlet</​groupId>
        <artifactId>javax.servlet-api</​artifactId>
        <version>4.0.1</​version>
        <scope>provided</​scope>
    </​dependency>

    <!-- Runtime: Not needed for compilation, packaged -->
    <dependency>
        <groupId>mysql</​groupId>
        <artifactId>mysql-connector-java</​artifactId>
        <version>8.0.33</​version>
        <scope>runtime</​scope>
    </​dependency>

    <!-- Test: Only for tests -->
    <dependency>
        <groupId>org.junit.jupiter</​groupId>
        <artifactId>junit-jupiter</​artifactId>
        <version>5.10.1</​version>
        <scope>test</​scope>
    </​dependency>

    <!-- System: From local filesystem -->
    <dependency>
        <groupId>com.example</​groupId>
        <artifactId>custom-lib</​artifactId>
        <version>1.0</​version>
        <scope>system</​scope>
        <systemPath>${project.basedir}/​lib/​custom-lib.jar</​systemPath>
    </​dependency>

    <!-- Import: For dependency management (BOM) -->
    <dependency>
        <groupId>org.springframework.boot</​groupId>
        <artifactId>spring-boot-dependencies</​artifactId>
        <version>3.2.0</​version>
        <type>pom</​type>
        <scope>import</​scope>
    </​dependency>
</​dependencies>

Project Structure

Standard Maven Layout

my-app/
├── pom.xml
├── src/
│   ├── main/
│   │   ├── java/
│   │   │   └── com/
│   │   │       └── example/
│   │   │           ├── Main.java
│   │   │           ├── model/
│   │   │           ├── service/
│   │   │           └── repository/
│   │   ├── resources/
│   │   │   ├── application.properties
│   │   │   ├── logback.xml
│   │   │   └── db/
│   │   │       └── migration/
│   │   └── webapp/  (for web apps)
│   │       ├── WEB-INF/
│   │       │   └── web.xml
│   │       └── index.html
│   └── test/
│       ├── java/
│       │   └── com/
│       │       └── example/
│       │           └── MainTest.java
│       └── resources/
│           └── test.properties
├── target/  (generated, git-ignored)
└── .gitignore

Multi-Module Project

parent-project/
├── pom.xml (parent)
├── module-core/
│   ├── pom.xml
│   └── src/
├── module-api/
│   ├── pom.xml
│   └── src/
├── module-web/
│   ├── pom.xml
│   └── src/
└── module-cli/
    ├── pom.xml
    └── src/

<!-- Parent pom.xml -->
<?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>

    <groupId>com.example</​groupId>
    <artifactId>parent-project</​artifactId>
    <version>1.0.0-SNAPSHOT</​version>
    <packaging>pom</​packaging>

    <modules>
        <module>module-core</​module>
        <module>module-api</​module>
        <module>module-web</​module>
        <module>module-cli</​module>
    </​modules>

    <properties>
        <maven.compiler.source>17</​maven.compiler.source>
        <maven.compiler.target>17</​maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</​project.build.sourceEncoding>
    </​properties>

    <dependencyManagement>
        <dependencies>
            <!-- Shared dependency versions -->
            <dependency>
                <groupId>org.springframework.boot</​groupId>
                <artifactId>spring-boot-dependencies</​artifactId>
                <version>3.2.0</​version>
                <type>pom</​type>
                <scope>import</​scope>
            </​dependency>
        </​dependencies>
    </​dependencyManagement>
</​project>

<!-- Child module pom.xml -->
<?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.example</​groupId>
        <artifactId>parent-project</​artifactId>
        <version>1.0.0-SNAPSHOT</​version>
    </​parent>

    <artifactId>module-core</​artifactId>

    <dependencies>
        <!-- Dependencies without version (managed by parent) -->
        <dependency>
            <groupId>org.springframework.boot</​groupId>
            <artifactId>spring-boot-starter</​artifactId>
        </​dependency>
    </​dependencies>
</​project>

Dependency Management

Adding Dependencies

# Manually add to pom.xml
# Or search on https://mvnrepository.com

# Dependency format:
# <groupId>:<artifactId>:<version>

<dependency>
    <groupId>com.google.guava</​groupId>
    <artifactId>guava</​artifactId>
    <version>32.1.3-jre</​version>
</​dependency>

Dependency Analysis

# Show dependency tree
mvn dependency:tree

# Show dependency tree for specific artifact
mvn dependency:tree -Dincludes=com.google.guava:guava

# Analyze dependencies
mvn dependency:analyze

# List dependencies
mvn dependency:list

# Show updates available
mvn versions:display-dependency-updates

# Show plugin updates
mvn versions:display-plugin-updates

# Purge local repository
mvn dependency:purge-local-repository

Version Management

<!-- Using properties -->
<properties>
    <spring.version>5.3.31</​spring.version>
    <junit.version>5.10.1</​junit.version>
</​properties>

<dependencies>
    <dependency>
        <groupId>org.springframework</​groupId>
        <artifactId>spring-core</​artifactId>
        <version>${spring.version}</​version>
    </​dependency>
</​dependencies>

<!-- Using BOM (Bill of Materials) -->
<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</​groupId>
            <artifactId>spring-boot-dependencies</​artifactId>
            <version>3.2.0</​version>
            <type>pom</​type>
            <scope>import</​scope>
        </​dependency>
    </​dependencies>
</​dependencyManagement>

<!-- Dependencies without versions (from BOM) -->
<dependencies>
    <dependency>
        <groupId>org.springframework.boot</​groupId>
        <artifactId>spring-boot-starter-web</​artifactId>
        <!-- Version from BOM -->
    </​dependency>
</​dependencies>

Excluding Transitive Dependencies

<dependency>
    <groupId>com.example</​groupId>
    <artifactId>some-library</​artifactId>
    <version>1.0.0</​version>
    <exclusions>
        <exclusion>
            <groupId>commons-logging</​groupId>
            <artifactId>commons-logging</​artifactId>
        </​exclusion>
    </​exclusions>
</​dependency>

Plugin Configuration

Common Plugins

Compiler Plugin
<plugin>
    <groupId>org.apache.maven.plugins</​groupId>
    <artifactId>maven-compiler-plugin</​artifactId>
    <version>3.11.0</​version>
    <configuration>
        <source>17</​source>
        <target>17</​target>
        <encoding>UTF-8</​encoding>
        <compilerArgs>
            <arg>-parameters</​arg>
            <arg>-Xlint:unchecked</​arg>
        </​compilerArgs>
    </​configuration>
</​plugin>
Surefire Plugin (Unit Tests)
<plugin>
    <groupId>org.apache.maven.plugins</​groupId>
    <artifactId>maven-surefire-plugin</​artifactId>
    <version>3.2.2</​version>
    <configuration>
        <includes>
            <include>**/​*Test.java</​include>
            <include>**/​*Tests.java</​include>
        </​includes>
        <argLine>-Xmx1024m</​argLine>
    </​configuration>
</​plugin>
Failsafe Plugin (Integration Tests)
<plugin>
    <groupId>org.apache.maven.plugins</​groupId>
    <artifactId>maven-failsafe-plugin</​artifactId>
    <version>3.2.2</​version>
    <executions>
        <execution>
            <goals>
                <goal>integration-test</​goal>
                <goal>verify</​goal>
            </​goals>
        </​execution>
    </​executions>
</​plugin>
JAR Plugin
<plugin>
    <groupId>org.apache.maven.plugins</​groupId>
    <artifactId>maven-jar-plugin</​artifactId>
    <version>3.3.0</​version>
    <configuration>
        <archive>
            <manifest>
                <addClasspath>true</​addClasspath>
                <mainClass>com.example.Main</​mainClass>
            </​manifest>
        </​archive>
    </​configuration>
</​plugin>
Assembly Plugin (Fat JAR)
<plugin>
    <groupId>org.apache.maven.plugins</​groupId>
    <artifactId>maven-assembly-plugin</​artifactId>
    <version>3.6.0</​version>
    <configuration>
        <descriptorRefs>
            <descriptorRef>jar-with-dependencies</​descriptorRef>
        </​descriptorRefs>
        <archive>
            <manifest>
                <mainClass>com.example.Main</​mainClass>
            </​manifest>
        </​archive>
    </​configuration>
    <executions>
        <execution>
            <id>make-assembly</​id>
            <phase>package</​phase>
            <goals>
                <goal>single</​goal>
            </​goals>
        </​execution>
    </​executions>
</​plugin>
Shade Plugin (Uber JAR)
<plugin>
    <groupId>org.apache.maven.plugins</​groupId>
    <artifactId>maven-shade-plugin</​artifactId>
    <version>3.5.1</​version>
    <executions>
        <execution>
            <phase>package</​phase>
            <goals>
                <goal>shade</​goal>
            </​goals>
            <configuration>
                <transformers>
                    <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                        <mainClass>com.example.Main</​mainClass>
                    </​transformer>
                </​transformers>
            </​configuration>
        </​execution>
    </​executions>
</​plugin>
Exec Plugin
<plugin>
    <groupId>org.codehaus.mojo</​groupId>
    <artifactId>exec-maven-plugin</​artifactId>
    <version>3.1.1</​version>
    <configuration>
        <mainClass>com.example.Main</​mainClass>
    </​configuration>
</​plugin>

# Run with exec plugin
mvn exec:java
mvn exec:java -Dexec.mainClass="com.example.Main"
mvn exec:java -Dexec.args="arg1 arg2"

Build Profiles

Profile Configuration

<profiles>
    <!-- Development Profile -->
    <profile>
        <id>dev</​id>
        <activation>
            <activeByDefault>true</​activeByDefault>
        </​activation>
        <properties>
            <env>development</​env>
            <database.url>jdbc:h2:mem:testdb</​database.url>
        </​properties>
        <dependencies>
            <dependency>
                <groupId>com.h2database</​groupId>
                <artifactId>h2</​artifactId>
                <scope>runtime</​scope>
            </​dependency>
        </​dependencies>
    </​profile>

    <!-- Production Profile -->
    <profile>
        <id>prod</​id>
        <properties>
            <env>production</​env>
            <database.url>jdbc:postgresql://prod-db:5432/​app</​database.url>
        </​properties>
        <dependencies>
            <dependency>
                <groupId>org.postgresql</​groupId>
                <artifactId>postgresql</​artifactId>
                <scope>runtime</​scope>
            </​dependency>
        </​dependencies>
        <build>
            <plugins>
                <plugin>
                    <groupId>org.apache.maven.plugins</​groupId>
                    <artifactId>maven-compiler-plugin</​artifactId>
                    <configuration>
                        <debug>false</​debug>
                        <optimize>true</​optimize>
                    </​configuration>
                </​plugin>
            </​plugins>
        </​build>
    </​profile>

    <!-- Test Profile -->
    <profile>
        <id>test</​id>
        <properties>
            <env>test</​env>
        </​properties>
    </​profile>
</​profiles>

# Activate profile
mvn clean install -Pprod

# Activate multiple profiles
mvn clean install -Pdev,integration-tests

# List active profiles
mvn help:active-profiles

# Show profile-specific settings
mvn help:effective-pom -Pprod

Common Issues & Solutions

Issue: Dependency Not Found

# Error: Could not find artifact

# Solution 1: Check repository configuration
mvn dependency:tree

# Solution 2: Update Maven metadata
mvn -U clean install  # -U forces update

# Solution 3: Clear local repository
rm -rf ~/​.m2/​repository/​com/​example/​problematic-artifact
mvn clean install

# Solution 4: Check network/​proxy settings
# Add to ~/​.m2/​settings.xml

<settings>
    <proxies>
        <proxy>
            <id>example-proxy</​id>
            <active>true</​active>
            <protocol>http</​protocol>
            <host>proxy.example.com</​host>
            <port>8080</​port>
        </​proxy>
    </​proxies>
</​settings>

Issue: Version Conflicts

# Show dependency conflicts
mvn dependency:tree -Dverbose

# Analyze dependency conflicts
mvn dependency:analyze-duplicate

# Solution: Use dependencyManagement

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>com.google.guava</​groupId>
            <artifactId>guava</​artifactId>
            <version>32.1.3-jre</​version>
        </​dependency>
    </​dependencies>
</​dependencyManagement>

Issue: Corrupted Repository

# Clean local repository
mvn dependency:purge-local-repository

# Or manually remove
rm -rf ~/​.m2/​repository

# Rebuild
mvn clean install

Issue: Out of Memory

# Increase Maven memory
export MAVEN_OPTS="-Xmx2048m -XX:MaxPermSize=512m"

# Or set in .mavenrc
echo "MAVEN_OPTS='-Xmx2048m'" > ~/​.mavenrc

# For Windows (setenv.bat)
set MAVEN_OPTS=-Xmx2048m -XX:MaxPermSize=512m

Issue: Slow Builds

# Use parallel builds
mvn -T 4 clean install  # 4 threads
mvn -T 1C clean install # 1 thread per CPU core

# Skip tests
mvn clean install -DskipTests

# Offline mode (use local repository only)
mvn -o clean install

# Use incremental builds
mvn clean install -amd  # Also make dependents

settings.xml Configuration

Local Repository and Mirrors

<!-- ~/​.m2/​settings.xml -->
<settings xmlns="http://maven.apache.org/SETTINGS/1.0.0"
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.0.0
          http://maven.apache.org/xsd/settings-1.0.0.xsd">

    <!-- Local Repository -->
    <localRepository>${user.home}/​.m2/​repository</​localRepository>

    <!-- Mirrors -->
    <mirrors>
        <mirror>
            <id>nexus</​id>
            <name>Nexus Repository</​name>
            <url>https://nexus.example.com/repository/maven-public/</​url>
            <mirrorOf>*</​mirrorOf>
        </​mirror>
    </​mirrors>

    <!-- Servers (Authentication) -->
    <servers>
        <server>
            <id>nexus-releases</​id>
            <username>deployment</​username>
            <password>password123</​password>
        </​server>
    </​servers>

    <!-- Profiles -->
    <profiles>
        <profile>
            <id>nexus</​id>
            <repositories>
                <repository>
                    <id>central</​id>
                    <url>https://nexus.example.com/repository/maven-public/</​url>
                    <releases><enabled>true</​enabled></​releases>
                    <snapshots><enabled>true</​enabled></​snapshots>
                </​repository>
            </​repositories>
        </​profile>
    </​profiles>

    <activeProfiles>
        <activeProfile>nexus</​activeProfile>
    </​activeProfiles>
</​settings>

Testing Configuration

JUnit 5

<dependencies>
    <dependency>
        <groupId>org.junit.jupiter</​groupId>
        <artifactId>junit-jupiter</​artifactId>
        <version>5.10.1</​version>
        <scope>test</​scope>
    </​dependency>

    <dependency>
        <groupId>org.mockito</​groupId>
        <artifactId>mockito-core</​artifactId>
        <version>5.7.0</​version>
        <scope>test</​scope>
    </​dependency>

    <dependency>
        <groupId>org.assertj</​groupId>
        <artifactId>assertj-core</​artifactId>
        <version>3.24.2</​version>
        <scope>test</​scope>
    </​dependency>
</​dependencies>

Code Coverage (JaCoCo)

<plugin>
    <groupId>org.jacoco</​groupId>
    <artifactId>jacoco-maven-plugin</​artifactId>
    <version>0.8.11</​version>
    <executions>
        <execution>
            <goals>
                <goal>prepare-agent</​goal>
            </​goals>
        </​execution>
        <execution>
            <id>report</​id>
            <phase>test</​phase>
            <goals>
                <goal>report</​goal>
            </​goals>
        </​execution>
        <execution>
            <id>check</​id>
            <goals>
                <goal>check</​goal>
            </​goals>
            <configuration>
                <rules>
                    <rule>
                        <element>PACKAGE</​element>
                        <limits>
                            <limit>
                                <counter>LINE</​counter>
                                <value>COVEREDRATIO</​value>
                                <minimum>0.80</​minimum>
                            </​limit>
                        </​limits>
                    </​rule>
                </​rules>
            </​configuration>
        </​execution>
    </​executions>
</​plugin>

# Generate coverage report
mvn clean test jacoco:report

# View report at target/​site/​jacoco/​index.html

CI/​CD Configuration

GitHub Actions

name: Maven Build

on: [push, pull_request]

jobs:
  build:
    runs-on: ubuntu-latest

    steps:
    - uses: actions/​checkout@v4

    - name: Set up JDK 17
      uses: actions/​setup-java@v4
      with:
        java-version: '17'
        distribution: 'temurin'
        cache: 'maven'

    - name: Build with Maven
      run: mvn clean install -B

    - name: Run tests
      run: mvn test

    - name: Generate coverage report
      run: mvn jacoco:report

    - name: Upload coverage to Codecov
      uses: codecov/​codecov-action@v3
      with:
        files: ./​target/​site/​jacoco/​jacoco.xml

GitLab CI

image: maven:3.9-eclipse-temurin-17

variables:
  MAVEN_OPTS: "-Dmaven.repo.local=$CI_PROJECT_DIR/​.m2/​repository"

cache:
  paths:
    - .m2/​repository

stages:
  - build
  - test
  - package

build:
  stage: build
  script:
    - mvn compile

test:
  stage: test
  script:
    - mvn test
    - mvn jacoco:report
  artifacts:
    reports:
      junit:
        - target/​surefire-reports/​TEST-*.xml
    paths:
      - target/​site/​jacoco

package:
  stage: package
  script:
    - mvn package -DskipTests
  artifacts:
    paths:
      - target/​*.jar

Best Practices Summary

Project Organization

  • Follow standard Maven directory layout
  • Use multi-module structure for large projects
  • Keep pom.xml clean and organized
  • Use properties for version management
  • Document custom configuration

Dependency Management

  • Use dependencyManagement for version control
  • Prefer BOMs for framework dependencies
  • Minimize dependencies
  • Regularly update dependencies
  • Use appropriate scopes
  • Exclude unnecessary transitive dependencies

Build Configuration

  • Use build profiles for different environments
  • Configure plugins properly
  • Use appropriate packaging type
  • Set Java version explicitly
  • Enable parallel builds when possible

Testing

  • Separate unit and integration tests
  • Use JaCoCo for code coverage
  • Set coverage thresholds
  • Run tests in CI/​CD pipeline
  • Use appropriate test frameworks

Performance

  • Use parallel builds (-T)
  • Enable offline mode when possible
  • Use Maven repository manager (Nexus/​Artifactory)
  • Configure appropriate memory settings
  • Cache dependencies in CI/​CD

Quick Reference Commands

# Project lifecycle
mvn clean                    # Clean build artifacts
mvn compile                  # Compile source code
mvn test                     # Run tests
mvn package                  # Create JAR/​WAR
mvn install                  # Install to local repo
mvn deploy                   # Deploy to remote repo

# Dependency management
mvn dependency:tree          # Show dependency tree
mvn dependency:analyze       # Analyze dependencies
mvn versions:display-dependency-updates  # Check for updates

# Running
mvn exec:java                # Run main class
mvn spring-boot:run          # Run Spring Boot app

# Profiles
mvn clean install -Pprod     # Activate profile

# Options
mvn clean install -DskipTests      # Skip tests
mvn clean install -T 4             # Parallel build
mvn clean install -U               # Force update
mvn clean install -o               # Offline mode

# Information
mvn help:effective-pom       # Show effective POM
mvn help:active-profiles     # Show active profiles

Notes

  • Always use dependencyManagement for multi-module projects
  • Keep Maven version up to date
  • Use Maven Wrapper (mvnw) for consistent builds
  • Configure settings.xml for organization-wide settings
  • Use profiles for environment-specific configuration
  • Enable parallel builds for faster compilation
  • Set up repository manager for better performance
  • Use BOMs to manage framework versions
  • Document custom plugin configurations
  • Regularly audit and update dependencies