# jni-maven

**Repository Path**: tony.yang/jni-maven

## Basic Information

- **Project Name**: jni-maven
- **Description**: No description available
- **Primary Language**: Unknown
- **License**: MIT
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2024-03-09
- **Last Updated**: 2024-03-09

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

jni-maven
=========

jni-maven is a sample project intended to be used as a template for Java applications using JNI.

Requirements
------------

You'll need the following:
- JDK
- gcc
- maven
- ant
- make

Usage
-----

```bash
git clone https://github.com/gkubisa/jni-maven.git jni-maven
cd jni-maven
mvn package
java -cp target/jni-maven-1.0-SNAPSHOT.jar ie.agisoft.App
```

How it works
------------

[maven-antrun-plugin][] is added to the *process-classes* phase of the build. It is used to:

- generate the C++ headers using *javah*. They are created in src/main/c++. 
  I did not use *javah* ant target, because it assumes Sun JDK, while I'm using OpenJDK.
- run *make* to build the native code

The Makefile compiles the native code from src/main/c++ into \*.o files which are stored in target/c++. 
Then it runs the linker which produces a single \*.so object stored in *target/classes*.

Because the \*.so file is in *target/classes*, it's included in the final JAR file. This way the
whole project produces a single artifact and can be easily used as a dependency by other Maven projects.

The final bit is the custom module loader *LibraryLoader.loadLibrary*, which extracts the 
native library from the jar into a temporary file and loads it - the standard *System.loadLibrary* cannot do it.

Limitations / possible improvements
-----------------------------------

1. Native code build currently works only on Linux
2. Only C++ is supported as the native language
3. The paths in the Makefile are hard-coded. It would be nice to initialize them from Maven properties.

**Patches welcome!**

Credits
-------

1. <http://docs.codehaus.org/display/MAVENUSER/Projects+With+JNI> - *jni-maven* is a simplified 
   implementation of the concept presented in this article
2. <http://code.google.com/p/jav8/> - *LibraryLoader* class in based on the code from this 
   project (*V8ScriptEngineFactory.java*)

[maven-antrun-plugin]: http://maven.apache.org/plugins/maven-antrun-plugin/