使用

環境:win10/Android studio 3.2

1.環境配置

在SDK Tools里選擇 CMAKE/LLDB/NDK點擊OK 安裝這些插件.

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2.創建CMakeLists.txt文件

在Project 目錄下,右鍵app，點擊新建File文件,命名為CMakeLists.txt

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3.配置文件

在CMakeLists.txt文件里添加如下代碼

# 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.
             test_lib #.so庫名 可自定義

             # Sets the library as a shared library.
             SHARED

             # Provides a relative path to your source file(s).
             src/main/jni/test_lib.c ) #源文件所在目錄
# 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.
                       test_lib #.so庫名 可自定義
                       # Links the target library to the log library
                       # included in the NDK.
                       ${log-lib} )

4.創建一個新的java類

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類中代碼

package com.example.myndkdemo;


public class Test_lib {
    static {
        System.loadLibrary("test_lib");//加載.so庫
    }

    public static native String getStr(String str);//調用C/C++接口函數

}

5.在main下面創建jni目錄，創建test_lib.c文件，名字必須與CMakeLists.txt文件的源文件所在目錄一致

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6.右鍵app，點擊Link C++ Project with Gradle

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顯示如下，選擇CMakeLists.txt文件所在路徑，點擊ok，等待構建完成.

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構建完成后，build.gradle文件會自動生成一些配置，如下圖:

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7.回到Test_lib.java文件,選中getStr()函數，按下Alt+Enter，點擊Create function...,如下圖。

此時會在test_lib.c文件里自動生成C/C++函數。接著就可以在.c文件里編寫C/C++接口函數了。

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此處有一個關于returnValue的報錯，不用理會，把它換掉就行。

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8.在其他java類中調用C/C++函數

在要調用的java類中導入Test_lib包:

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大功告成！

調試

如果 C 或 C++ 那邊代碼出問題了，調試起來要命的，之前只能 log，現在 Android Studio 提供了打斷點來 debug C 或 C++ 代碼，需要使用 LLDB 來檢測到 C 或 C++ 代碼中的斷點，這里要使用 externalNativeBuild 方式自動編譯 C/C++ 代碼，才能進入斷點進行調試。

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Native 模式
選擇 run 下拉 item，選 Edit Configurations，彈出配置窗體，1、添加；2、Name： app-native；3、Module 還是選擇 app；4、Debugger 選擇 Native，只想使用 LLDB 來調試代碼，忽略 Java 代碼中的斷點。

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感謝：
在Android studio 3.2 版項目中使用cmake調用C/C++
Android NDK 入門與實踐