Android在Module中引入Native C++

前言

• 在新建的Lib中，As是没有Native C++项目的，需要自己手动建立
• 此方法在Project中也生效
• 环境 AS 3.5.2 ，ndk 22.1.7171670 , 23的ndk有问题暂时没用

解决方案

• 设置ndk目录

  
  步骤一

• AS下载的没有platforms文件夹(没有文件夹，选中目录会报错)，新建一个空白文件夹叫此名即可

• 项目切换到Project模式
  

  image.png

• 在main下新建cpp
  

  image.png

• 可以新建一个Native项目，把CMakeLists.txt和native-lib.cpp移动出来，此处方便我直接贴出来

# For more information about using CMake with Android Studio, read the
# documentation: https://d.android.com/studio/projects/add-native-code.html

# Sets the minimum version of CMake required to build the native library.

cmake_minimum_required(VERSION 3.4.1)

# Creates and names a library, sets it as either STATIC
# or SHARED, and provides the relative paths to its source code.
# You can define multiple libraries, and CMake builds them for you.
# Gradle automatically packages shared libraries with your APK.

add_library( # Sets the name of the library.
             native-lib

             # Sets the library as a shared library.
             SHARED

             # Provides a relative path to your source file(s).
             native-lib.cpp )

# Searches for a specified prebuilt library and stores the path as a
# variable. Because CMake includes system libraries in the search path by
# default, you only need to specify the name of the public NDK library
# you want to add. CMake verifies that the library exists before
# completing its build.

find_library( # Sets the name of the path variable.
              log-lib

              # Specifies the name of the NDK library that
              # you want CMake to locate.
              log )

# Specifies libraries CMake should link to your target library. You
# can link multiple libraries, such as libraries you define in this
# build script, prebuilt third-party libraries, or system libraries.

target_link_libraries( # Specifies the target library.
                       native-lib

                       # Links the target library to the log library
                       # included in the NDK.
                       ${log-lib} )

#include <jni.h>
#include <string>

extern "C" JNIEXPORT jstring JNICALL
Java_com_blog_hooklibrary_jni_Query_stringFromJNI(  //改名称
        JNIEnv *env,
        jobject /* this */) {
    std::string hello = "Hello from C++";
    return env->NewStringUTF(hello.c_str());
}

• 切回Android文件目录，找到Lib依赖
  image.png

• 在android{...}下添加

    externalNativeBuild {
        cmake {
            path "src/main/cpp/CMakeLists.txt"  //根据自己的目录调整
            version "3.10.2"
        }
    }

• java文件

public class Query {


    static {
        System.loadLibrary("native-lib");
    }



    public native String stringFromJNI();
}

• 最后，使用此方法

  
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