Can Native and JNI Libraries Be Packaged Together in a JAR for Simplified Distribution?

Encapsulating Native and JNI Libraries Within a Single JAR

Problem:

Incorporating the Tokyo Cabinet library into a JAR to simplify distribution while avoiding the need for manual library redistribution. The current available solution faces limitations in including the native library and restricting its use to a specific plugin.

Solution: Can Native and JNI Libraries Be Packaged Together in a JAR?

Yes, creating a unified JAR containing the native JNI library for various platforms is feasible. System.load(File) can be used to load the library, bypassing the usual System.loadLibrary(String) and eliminating the requirement for system-level library installation. The drawback lies in potential platform incompatibility, as the JAR may not include libraries for all supported platforms.

Process:

1. JAR Assembly: Include native JNI libraries within the JAR at a platform-specific location, such as "NATIVE/${os.arch}/${os.name}/libname.lib".

2. Static Initialization: Implement a static initializer within the main class that:

   • Determines the current os.arch and os.name
   • Searches for the library within the JAR using Class.getResource(String)
   • Extracts the library to a temporary file and loads it via System.load(File) if present

Hybrid Solution:

A hybrid approach can be employed, allowing for both embedded library loading and system-wide library search along the java.library.path. This ensures compatibility for platforms where the embedded library is unavailable.

Example Implementation:

The jzmq Java bindings of ZeroMQ showcase this functionality. Its code, available [here](link to jzmq code), provides a seamless loading experience while maintaining platform flexibility.

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