Android Studio 2.2 Jni 调试

Jni是android提供的与其他语言交互的接口，常用的就是c或c++，之前写jni代码是非常痛苦的，一方面像写记事本一样没有各种函数提示，一方面无法调试，单靠打log效率非常低，所以之前都有点不想写jni的代码，但是最近得知了jni可以像Java一样动态调试，非常感兴趣，经过一番折腾，把具体步骤介绍一下。

 

1、环境：

   Android studio 2.2以上

   Jdk 1.8以上

   NDK r12+

   安装CMake、LLDB

2、新建工程，将Include C++ Support勾上

 

 

 

 

 

 

 

3、C++ Standard选默认的就行，下面第一个“Exception Support”代表处理c++异常，最好勾上，点击Finish

 

 

4、目录主要变化，因为采用CMake,所以默认C代码放在cpp目录下，然后比较重要的一个文件是CMakeLists.txt

 

 

 

5、CMakeLists介绍，如下是CMakeLists文件的内容：

 

#Sets the minimum version of CMake required to build the native # library. You should either keep the default value or only pass a # value of 3.4.0 or lower. 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 it for you. # Gradle automatically packages shared libraries with your APK. include_directories( imported-lib/include/ ) add_library( # Sets the name of the library. native-lib2 # Sets the library as ashared library. SHARED # Provides a relative pathto your source file(s). # Associated headers in thesame location as their source # file are automaticallyincluded. src/main/cpp/native-lib.cpp) add_library(tmms-au SHARED src/main/cpp/tmms-au-jni.c) add_library(tmloader STATIC IMPORTED) set_target_properties( # Specifies the target library. tmloader # Specifies theparameter you want to define. PROPERTIESIMPORTED_LOCATION # Provides thepath to the library you want to import. src/main/cpp/libtmloader.a ) # Searches for a specified prebuilt library and stores the path as a # variable. Because system libraries are included 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 theNDK 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 the # build script, prebuilt third-party libraries, or system libraries. target_link_libraries(tmms-au tmloader ${log-lib}) target_link_libraries( # Specifies the target library. native-lib2 # Links the targetlibrary to the log library # included in theNDK. ${log-lib} )

  说明： 1、 include_directories( imported-lib/include/ )作用就是将所有头文件放在一个目录里，然后指定目录位置，以后在c代码中include就不需要加路径了。 2、 add_library(native-lib SHARED src/main/cpp/native-lib.cpp)该函数负责生成so文件相关信息，第一个参数是so文件名称，第二个是类型，比如SHARED就是动态链接库；第三个就是c文件所在路径，注意头文件可以直接在c代码中包含路径就行，可以不用在这边写。另外这个方法也可以用来导入其他的so文件，例如add_library(native-lib SHARED IMPORTED)，但是调用这个后一定要通过set_target_properties设置可执行文件的位置。 3、 find_library（log-lib log）是寻找NDK本地so文件,第一个参数是保存要找的so文件的路径变量名，下面会用到，第二个参数就是要找的NDK中的so文件名。 4、 target_link_libraries（native-lib imported-lib ... ${log-lib}）作用是将其他的库导入到你的目标so中，第一个参数就是目标so文件，后面的都是要导入的其他库。 5、 接下来就能按照上面的步骤创建多个属于自己的so文件了         6、build.gradle介绍：  

applyplugin: 'com.android.application' android { compileSdkVersion 25 buildToolsVersion "24.0.1" defaultConfig { applicationId "com.example.myapplication" minSdkVersion 17 targetSdkVersion 22 versionCode 1 versionName "1.0" testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner" externalNativeBuild { cmake { cppFlags "-fexceptions" } } ndk { // Specifies the ABIconfigurations of your native // libraries Gradle shouldbuild and package with your APK. abiFilters 'armeabi' } } buildTypes { release { minifyEnabled false proguardFilesgetDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro' } } /* externalNativeBuild { // Encapsulates your CMake buildconfigurations. cmake { // Provides a relative pathto your CMake build script. path"CMakeLists.txt" } }*/ externalNativeBuild { ndkBuild { path "src/main/jni/Android.mk" } } } dependencies { compile fileTree(dir: 'libs', include:['*.jar']) androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2',{ exclude group: 'com.android.support',module: 'support-annotations' }) compile 'com.android.support:appcompat-v7:25.0.0' testCompile 'junit:junit:4.12' }

1） defaultConfig.externalNativeBuild,里面就是之前创建项目指定的一些选项，另外defaultConfig.ndk负责指定需要创建哪些类型的so文件，最好指定一下，不然会全部创建，非常慢的。2) externalNativeBuild{        // Encapsulates your CMake buildconfigurations.        cmake {            // Provides a relative pathto your CMake build script.            path"CMakeLists.txt"        } 这个负责指定CMakeLists.txt文件路径。另外如果想要采用NDK来编译，就要改成externalNativeBuild {        ndkBuild {            path "src/main/jni/Android.mk"        }  } 7、开始调试 按照上面所有步骤配置好后就能开始调试了，比较麻烦的一点是每次修改CMakeLists.txt最好要clean project一下，不然会出现很多没必要的问题，这种方式和之前gradle-experimental创建的jni调试效果差不多，就是比较方便，不用修改插件了。好了，可以尽情的调试你的c代码了！