Getting Started with Maven

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Overview

If you're a Java developer, you've likely used Maven to build and manage your projects.

In this post, you'll learn the basics of using Maven in your projects.

Understanding Maven's Project Structure

• my-maven-project/pom.xml

Defines the Maven project. It includes a unique identifier for the project, properties, dependencies, and necessary modules.

• my-maven-project/src/main/java

Contains the source code of the project.

• my-maven-project/src/main/resources

Contains resource files (like application.properties).

• my-maven-project/src/test

Contains the test code.

• my-maven-project/src/it

Contains integration tests.

• my-maven-project/target

Contains compiled classes, JAR/WAR files, and other artifacts.

POM File

Key Elements

The pom.xml file holds crucial information about the project. Each project must have a unique identifier, specified by:

groupId (usually your domain name)
artifactId (usually the project name)
version (project version)

Additionally, the pom.xml can include the project's name, description, and packaging type (e.g., JAR/WAR).

Example:

<groupId>com.kramti</groupId>

<artifactId>example</artifactId>

<version>1.0</version>

<name>My Maven Example</name>

<description>This is a Maven pom.xml example</description>

<packaging>war</packaging>

<properties>

<java.version>21</java.version>

</properties>

Dependencies

Dependencies are external libraries your project requires. Instead of manually downloading and importing JAR files, Maven simplifies this by managing dependencies within the pom.xml.

To add a dependency, you need its groupId, artifactId, version (optional), and scope (optional). You can find dependencies on the Maven Repository.

Example of a dependency:

<dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-data-jpa</artifactId>

<version></version>

</dependency>

For example, if you need a dependency only for testing purposes, use the scope tag:

<dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-test</artifactId>

<scope>test</scope>

</dependency>

Maven Build Lifecycle

• validate: Checks if the project is correct and all necessary information is available.

• compile: Compiles the project's source code.

• test: Runs unit tests using a suitable testing framework.

• package: Packages the compiled code into a distributable format (e.g., JAR or WAR).

• install: Installs the package into the local repository for use by other projects.

• deploy: Deploys the built package to a remote repository for sharing with other developers.

Maven Plugins

Using Maven Plugins Maven plugins are essential for customizing the build process. You can use plugins for tasks such as compiling code, running tests, and generating reports.

Example of a compiler plugin:

<plugin>

<groupId>org.apache.maven.plugins</groupId>

<artifactId>maven-compiler-plugin</artifactId>

<version>3.8.1</version>

<configuration>

<source>1.8</source>

<target>1.8</target>

</configuration>

</plugin>

Popular plugins include:

maven-compiler-plugin: Compiles Java source code.

maven-surefire-plugin: Runs unit tests.

maven-jar-plugin: Packages the project into a JAR file.

Best Practices for Maven Projects

Keep Dependencies Up-to-Date: Regularly update your dependencies to avoid vulnerabilities.

Avoid Version Conflicts: Use the section in the parent POM to manage dependency versions in multi-module projects.

Minimize Plugin Configuration: Keep plugin configurations minimal and only configure what’s necessary for your project.

Build performance: For large projects, Maven builds can be slow. Use the -T option to enable parallel builds

Conclusion

Maven is an essential tool for Java developers. It simplifies project management by automating builds, handling dependencies and plugins. Understanding its structure, POM file, and core features allows for more efficient and organized workflows.

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Comments

[Karl Heinz Marbaise]

The given location my-maven-project/src/resources is wrong ... this should be my-maven-project/src/main/resources instead.
The idea having integration tests within my-maven-project/src/it is a bad idea...better go with src/test/java and use appropriate naming conventions which is defined by maven.apache.org/surefire/maven-fa...