This demo uses the gazelle extension from rules_jvm to generate rules for the maven hello world example generated with the following command.

mvn archetype:generate -DgroupId=com.mycompany.app -DartifactId=my-app -DarchetypeArtifactId=maven-archetype-quickstart -DarchetypeVersion=1.4 -DinteractiveMode=false

The following dependency was added to the pom.xml file to demonstrate the use of external dependencies.

    <dependency>
	<groupId>com.fasterxml.jackson.core</groupId>
	<artifactId>jackson-databind</artifactId>
	<version>2.15.3</version>
    </dependency>

This way, we are able to use the jackson library in the App.java file.

import com.fasterxml.jackson.databind.ObjectMapper;

To be able to use this dependency when building with Bazel, we will use rules_jvm_external and add it to the maven_install rule of the WORKSPACE file.

maven_install(
    artifacts = [
        "com.fasterxml.jackson.core:jackson-databind:2.15.3"
    ],
	...
)

As explained here Bazel can pin the external dependencies to the maven_install.json file. This is also important to let gazelle know about these external dependencies for the BUILD files generateion.

To generate the maven_install.json file, follow the instructions from the above link.

Setup gazelle as explained here : https://github.com/bazel-contrib/rules_jvm/tree/main/java/gazelle WORKSPACE file and top level BUILD files.

• Some more dependencies needed to be added in the WORKSPACE file.
• Because of the following issue this patch is added to the http_archive command that downloads the rules_jvm dependency in the WORKSPACE file.

Importantly: tell gazelle about the maven_install.json lockfile so that it can automatically add the external dependencies.

# gazelle:prefix com.mycompany.app
# gazelle:java_maven_install_file maven_install.json

bazel run //:gazelle

This will generate Bazel build file

Which contains the java_library that depends on the external jackson one, as well as a java_binary.

Which contains a java_test_suite target.