Can I add jars to Maven 2 build classpath without installing them?

java

maven-plugins

dependency-management

build-process

byAlex Kataev·Jan 31, 2025

You can swiftly include a local JAR to your Maven project through the definition of a system scope dependency in your pom.xml. Substitute placeholders with your JAR data and utilize the ${basedir} variable for referring to the relative path of the JAR.

<dependency>
  <groupId>custom-jar</groupId>
  <artifactId>mylocaljar</artifactId>
  <version>1.0</version>
  <scope>system</scope>
  <systemPath>${basedir}/lib/mylocaljar.jar</systemPath>
</dependency>

This offers an efficient, project-focused solution.

Introduce Your Local JARs Cleverly

Managing local JARs without junking up your Maven local repository is a classic challenge. So, how do we manage and simplify these dependencies within our project?

Homemade Dependency Directory

Keep your JARs in a format akin to the Maven repository structure (e.g., /groupId/artifactId/version/). This mimics Maven's structure, foster better organization.

Deploy Maven Plugins to Your Advantage

The Assembly or OneJar plugins can bundle all dependencies into a single archive, including your local JARs. Watch these transform your build and packaging phases:

<plugins>
  <!-- Just like Dr. Strange in Avengers, wave your magic coding wand and pick the right plugin here -->
</plugins>

Turn `pom.xml` into Your Local Repository

You can incorporate a local repository directly into your pom.xml. For each local dependency, define distinct groupId and artifactId. Keeps things clean and project-specific.

Add Some Automation Magic

Move away from the drag of manual dependency installation using utility scripts or Maven plugins. Get rid of individual pom.xml files for every JAR. (Nobody got time for that!)

Utility Scripts: Your New Best Friend

Create a script to batch install the JARs into your project's repository—consistent, efficient, and no more ad-hoc installs.

Modern problems, Maven solutions

Plugins such as maven-install-plugin helps to install JARs directly. Optionally, consider developing custom Maven plugins to simplify and automate the process, no POM changes required.

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-install-plugin</artifactId>
  <!--Slide in some configurations here, just like sliding into those DMs-->
</plugin>

Overcoming Common Hurdles

Roadblocks are common when adding JARs without installation. Allow me to be your traffic cop. Here's a brief navigation guide through these challenges:

Absolute Paths: Friend or Foe?

The system scope craves absolute paths, for better or worse. Use the ${basedir} variable for maintaining relative paths within your project. Think relative, not absolute.

Grouping JARs: United We Stand

Combine multiple JARs under a single Maven dependency for simple version management. This unites versions and ensures consistency in your dependency definitions.

Scripted Installation: A Double-Edged Sword

Scripts may simplify installation, but remember system scope dependencies are not transitively included in WAR or JAR assemblies. Ensure you have a plan B for distributing your project.

explain-codes / Java / Can I add jars to Maven 2 build classpath without installing them?

Linked

Maven: best way of linking custom external JAR to my project?



Maven compile with multiple src directories



Maven: add a dependency to a jar by relative path



How to build JARs from IntelliJ IDEA properly?



How can I create an executable/runnable JAR with dependencies using Maven?

