Maven Local Repository

Maven is a build automation tool used primarily for Java projects. One of its core features is dependency management, facilitated by repositories. A Maven repository is a directory where all the project jars, libraries, plugins, and other artifacts are stored and can be retrieved by Maven to be used in a project. This article explains the Maven Local Repository with an example.

When we create a Maven project, we need Maven dependencies to complete the software application. Maven Dependency Management first checks the local repository for dependencies. If unavailable, Maven Dependency Management downloads the required dependencies from the central repositories.

Default Location

A local repository is a directory on the developer's machine where Maven stores all the artifacts resolved from remote repositories or created by the developer. By default, this repository is located at:

Windows: C:\Users\{your-username}\.m2\repository
Unix-based systems: ~/.m2/repository

On Windows:

How the Maven Local Repository Works

When we run a Maven build command, Maven first checks if the required dependencies are available in the local repository. If not, Maven will check remote repositories. If the required dependencies are found, Maven downloads them and stores them in the local repository. Then Maven uses those dependencies from the local repository.

Explanation:

Below we provide step by step how maven local repository works for better understanding.

• Maven Build: The Maven Build process is started when you run maven build command like mvn clean and mvn install.
• Check Local Repository: After this Maven first checks local repository for required dependencies in this location ~/.m2/repository.
• Dependencies Found Locally: If required dependencies are available in the local repository then maven will use them.
• Dependency Not Found Locally: If required dependencies are not available in the local repository then Maven checks remote repositories.
• Download from Remote: If the dependency is available in a remote repository, Maven downloads it and stores it in the local repository.
• Use Downloaded Dependency: Once downloaded, Maven uses the dependency from the local repository for the build process.

This workflow ensures that Maven projects can be built efficiently by reusing previously downloaded dependencies and only downloading missing ones when necessary.

Example Maven Project

Main Application Class:

package com.app;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.security.servlet.SecurityAutoConfiguration;

@SpringBootApplication
public class MavenApp {

    public static void main(String[] args) {
        SpringApplication.run(MavenApp.class, args);
      System.out.println("Welcome to GeeksForGeeks")
    }

}

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 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>3.2.6</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.app</groupId>
    <artifactId>mavencommends</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>mavencommends</name>
    <description>Spring Reactive</description>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

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

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

</project>

Applications of Maven Local Repository

The Maven provide lot application for make development easy.

• Dependency Management: Simplifies dependency management by automatically handling downloads and updates.
• Offline Builds: Allows for offline builds using previously downloaded dependencies.
• Custom Repositories
  • Supports custom local repositories for internal libraries and artifacts.
  • Enables the use of proprietary or internal artifacts that are not available in public repositories.
• Build Performance: Speeds up builds by reusing previously downloaded dependencies and Reduces the need to download dependencies multiple times.
• Version Control: Facilitates easy rollback to previous versions if needed.