在 Android 项目中链接共享库 [英] Linking shared library in Android project

问题描述

我需要在 android studio 项目中导入一个用 C 文件编写的函数.此函数调用位于其他文件中的其他函数(总共 50 多个 C 文件和头文件).

I need to import a single function written in a C file in an android studio project. This function call others functions located in anothers files (50+ C files and headers in total).

这个项目已经包含一个 C++ 文件，因为我正在使用 NDK 编译 OpenCV4android.

This project already contains a single C++ file as I am using NDK to compile OpenCV4android.

我已经使用 Mingw 和 GCC 编译了一个共享库 (libfinal.so)，但是一旦我尝试导入它们，感谢 NDKbuild 我得到了这个毫无意义的错误:

I've used Mingw and GCC to compile a shared libraries (libfinal.so) but once i try to import them thanks to NDKbuild i got this meaningless error :

Error:Execution failed for task ':app:ndkBuild'.
> Process 'command 'C:/SDK/ndk-bundle/ndk-build.cmd'' finished with non-zero exit value 2

这是 Android.mk 文件:

Here is the Android.mk file :

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

/some opencv stuff/

include $(CLEAR_VARS)
LOCAL_MODULE := final
LOCAL_SRC_FILES := libfinal.so
LOCAL_EXPORT_C_INCLUDES := C:\SDK\NDKOpencvTest1\app\src\main\jni\include
include $(PREBUILT_SHARED_LIBRARY)

最后一行是给我错误的那一行.

The last line is the one giving me the error.

这是树层次结构:

http://imgur.com/a/G3I0y

我也试过这个解决方案但没有成功:如何在 Android Studio (ver 2.1.2) 上构建 FFmpeg (ver 3.1.1)

I've also tried this solution without success: How to build FFmpeg (ver 3.1.1) on Android Studio (ver 2.1.2)

几个小时以来，我一直在寻找我做错了什么..

I've been searching what I am doing wrong for hours..

非常感谢您的帮助！

推荐答案

您的层次结构错误.请按照以下步骤操作:

Your hierarchy is wrong. Follow these steps:

1. 在 jni 文件夹中创建lib"文件夹，并根据目标文件夹放置共享库.这应该类似于:'jni/lib/armeabi-v7a/libfinal.so'.

1. Create 'lib' folder in jni folder and put your shared libraries according target folders. This should look like: 'jni/lib/armeabi-v7a/libfinal.so'.

仅预构建 jni/lib 文件夹中的这些 .so 库.为此，将这一行 LOCAL_SRC_FILES := libfinal.so 更改为 LOCAL_SRC_FILES := lib/$(TARGET_ARCH_ABI)/libfinal.so.这将在 jni 文件夹中搜索 lib 文件夹，然后将根据您的 CPU 架构在目标文件夹中搜索 libfinal.so lib.

Prebuilt only these .so libs which are in jni/lib folder. For this, change this line LOCAL_SRC_FILES := libfinal.so to LOCAL_SRC_FILES := lib/$(TARGET_ARCH_ABI)/libfinal.so. This will search lib folder in jni folder, and then this will search libfinal.so lib in targetted folder according your cpu architecture.

注意你的 gradle 脚本.你应该像这样添加你的 Android.mk 文件，

Be aware of your gradle scripts. You should add your Android.mk file like this,

externalNativeBuild {
ndkBuild {
    path 'src/main/jni/Android.mk'
    }
}

构建 Android.mk 文件后，gradle 会根据目标 archs 将您的预构建库放在 main/jni 文件夹中.为此，将此行添加到 gradle，

After building Android.mk file, gradle puts your prebuilt libraries in main/jni folder according to targetted archs. For this, add this line to gradle,

sourceSets.main {
        jni.srcDirs = []
        jniLibs.srcDir 'src/main/libs'
    }

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