Android Studio3.5 JNI配置及使用

Android Studio3.5JNI配置及使用

一、下載安裝NDK以及CMake

1.1進入SDK Manager

• 主頁右上角

• File->Settings->Appearance & Behavior->System Settings->Android SDK

1.2開始下載

• 選中上方SDK Tools和下方的Show Package Details多選框
• 選中需要下載的NDK版本以及CMake版本，點擊右下角Apply即可

安裝目錄會在上方sdk目錄中的ndk目錄中

二、新建項目

1.1新建Native C++項目

1.2修改項目信息

1.3選擇C++版本

• 無特殊要求直接默認即可

1.4創建完成

• cpp目錄即爲c++代碼目錄

二、配置CMake

2.1CMakeLists.txt主配置文件

• 打開app目錄下的build.gradle文件
• path：主配置文件相對路徑
• version：版本號

externalNativeBuild {
    cmake {
        path "src/main/cpp/CMakeLists.txt"
        version "3.10.2"
    }
}

2.2CMakeLists.txt詳解

2.2.1文件解析

# 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.
# 聲明CMake版本
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.

# 創建和命名庫，將其設置爲靜態或共享，並提供到其源代碼的相對路徑。
# 您可以定義多個庫，然後CMake爲您構建它們。Gradle自動將共享庫打包到你的APK中。

# 添加cpp文件到庫中
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.

# 將log庫儲存爲一個名爲log-lib的變量
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.

# 在上方定義好的native-lib庫中引入log庫
target_link_libraries( # Specifies the target library.
        native-lib

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

2.2.2添加多個.cpp文件

add_library(
        native-lib
        SHARED
        native-lib.cpp
        one-lib.cpp
        two-lib.cpp)

2.2.3生成多個.so庫

• 在cpp目錄下新建文件夾，並在新建的文件夾下新建CMakeLists.txt文件

• 新建.cpp文件

• one目錄下CMakeLists.txt文件內容

add_library(one-lib SHARED one-lib.cpp)
target_link_libraries(one-lib log)

• two目錄下CMakeLists.txt文件內容

add_library(two-lib SHARED two-lib.cpp)
target_link_libraries(two-lib log)

• 在主配置文件下添加

add_subdirectory(one)
add_subdirectory(two)

參數傳入的是指定包含CMakeLists文件的目錄的相對路徑

• 點擊Build->Make Project
  • 打開app->build->intermediates->cmake->debug->obj中的任意文件夾

2.3詳細配置參閱官方文檔

Google Docs

CMake