java-maven-helper

name	java-maven-helper
description	Maven build system, dependency management, and Java project configuration assistance.

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>[e-mail]</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