Скачать или смотреть Linking Native Libraries in Different NDK Modules

Discover how to effectively link native libraries in different NDK modules of your Android application to enhance build performance.
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Linking Native Libraries in Different NDK Modules: A Comprehensive Guide

In modern Android app development, particularly when using the Android Native Development Kit (NDK), a common challenge arises when trying to modularize applications that heavily rely on native libraries. If your project has multiple modules—each containing its own native shared library—linking these libraries can become a complicated task, especially when they have interdependencies. Let’s break down how to effectively manage this situation.

The Problem at Hand

You may be facing a situation where you have:

A core library module at the base level.

An application library module built atop the core module.

The main application module on top of both.

Each of these modules generates its own native .so (shared object) file. For instance, let's say your application.so file needs to link to library.so and core.so, while library.so also needs to link to core.so. The challenge comes in when these files are created and you cannot find a way to have them effectively reference each other during the build process.

Understanding Build Dependencies

To clarify, when you try to set this up, you might initially consider using commands like find_library() or directly naming the libraries in target_link_libraries() within your Gradle setup. Unfortunately, these approaches may not yield the desired results. The error messages and lack of linking can be frustrating. Let’s explore a structured way to tackle it.

A Recommended Approach to Linking Native Libraries

Step 1: Combine Your Native Code

Single Gradle Module: The best practice for managing your native code is to consolidate it into a single Gradle module. This will help maximize your build performance and ensure that your project follows a supported usage model. Having separate modules for each native library typically leads to poorer performance due to the overhead created when invoking the build tools multiple times for each module.

Step 2: Use Prefab (With Caution)

Utilizing Prefabricated Libraries: You mentioned the buildFeatures setting and generating an AAR (Android Archive). It’s crucial to understand the purpose of Prefab. While it is designed for distributing independent libraries, it is typically not ideal for internal libraries. Using Prefab might complicate your project unnecessarily if you are looking to simply manage modularized source code without additional complexity.

Step 3: Direct Library Reference

Link Libraries Directly: If splitting modules is essential, and you’re adamant about keeping them separate, consider treating each as a separate project. However, this is not recommended unless absolutely necessary. You can reference the generated .so files from one module to another by using local file references in your Gradle scripts, like so:

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Conclusion: Simplifying Your Module Structure

While it may initially seem counterintuitive, simplifying your module structure can significantly enhance build performance and reduce complexity. Modulating your application into separate libraries is excellent for scalability but can lead to increased compile times, especially when native code is involved.

In summary, the key points to take away are:

Aim for a single Gradle module for your native code.

Use Prefab wisely—ideal for external libraries but overkill for internal dependencies.

Directly reference .so files if multiple modules are necessary, keeping in mind the performance implications.

By following these guidelines, you should be able to manage your NDK modules effectively and minimize the headaches associated with linking native libraries in your Android applications.