Contributing to Apache OpenDAL™ Java Bindings

This document covers building, testing, and styling the Java binding. For usage, see the user guide.

Build

This project provides OpenDAL Java bindings with artifact name opendal. It depends on JDK 8 or later.

You can use Maven to build both the Rust dynamic lib and JAR files with one command:

./mvnw clean package -DskipTests=true

Run tests

Currently, all tests are written in Java.

You can run the base tests with the following command:

./mvnw clean verify

Code style

This project uses spotless for code formatting so that all developers share a consistent code style without bikeshedding on it.

You can apply the code style with the following command:

./mvnw spotless:apply

Run behavior tests

Services behavior tests read necessary configs from env vars or the .env file.

You can copy .env.example to ${project.rootdir}/.env and change the values on need, or directly set env vars with export KEY=VALUE.

Take fs for example, we need to enable bench on fs on /tmp/:

OPENDAL_TEST=fs
OPENDAL_FS_ROOT=/tmp/

You can run service behavior tests of enabled services with the following command:

./mvnw test -Dtest="behavior.*Test"

Classified library

Note that the dependency without classifier ships all classes and resources except the "opendal_java" shared library. And those with classifier bundle only the shared library.

For downstream usage, it's recommended:

• Depend on the one without classifier to write code;
• Depend on the classified ones with "test" for testing.

To load the shared library correctly, you can choose one of the following approaches:

• Append the classified JARs to the classpath at the runtime;
• Depend on the classified JARs and build a fat JAR (You may need to depend on all the provided classified JARs for running on multiple platforms);
• Build your own "opendal_java" shared library and specify "-Djava.library.path" to the folder containing that shared library.

The musl native library is dynamically linked against musl libc and the GCC runtime. On Alpine Linux, install libgcc before loading the native library.