在Visual Studio中用CMakePresets.json交叉编译Android时如何选目标架构

问题背景 #

在Visual Studio 2022中使用CMake项目开发C++共享库，可正常编译Windows平台的.dll和WSL环境的.so，但编译Android版本时无法指定目标架构。采用Android NDK提供的工具链文件，官方要求ABI、minSdkVersion等参数需通过CMake命令行传入，但不清楚如何在CMakePresets.json中配置。曾尝试在CMakeLists.txt中设置ANDROID_ABI为arm64-v8a，但无效，编译出的库为32位，导入时抛出架构不匹配错误。

当前配置 #

CMakePresets.json 相关片段 #

{    
    "version": 3,    
    "configurePresets": [        
        {            
            "name": "android-arm64-debug",            
            "displayName": "Android Arm64 Debug",            
            "description": "Target Android with an Arm64 ABI.",            
            "generator": "Ninja",            
            "binaryDir": "${sourceDir}/out/build/${presetName}",            
            "installDir": "${sourceDir}/out/install/${presetName}",            
            "cacheVariables": { "CMAKE_BUILD_TYPE": "Debug" },            
            "toolchainFile": "C:/Program Files/Unity/Hub/Editor/2021.3.3f1/Editor/Data/PlaybackEngines/AndroidPlayer/NDK/build/cmake/android.toolchain.cmake",            
            "condition": {                
                "type": "equals",                
                "lhs": "${hostSystemName}",                
                "rhs": "Windows"            
            },            
            "vendor": { "microsoft.com/VisualStudioRemoteSettings/CMake/2.0": { "remoteSourceRootDir": "$env{HOME}/.vs/$ms{projectDirName}" } }        
        },
        // 其他配置已省略 ...    
    ]
}

根目录CMakeLists.txt 内容 #

set(MY_LIB my_lib)

## 尝试覆盖目标架构的无效代码 ##
if(ANDROID)    
    set(ANDROID_ABI arm64-v8a)
endif()
#############################

add_library(${MY_LIB} SHARED api.cpp)
target_link_libraries(${MY_LIB} core)
install(TARGETS ${MY_LIB}    
    RUNTIME DESTINATION bin    
    LIBRARY DESTINATION lib)

错误信息 #

导入库时抛出异常：

java.lang.UnsatisfiedLinkError: dlopen failed: "/data/app/~~lBHFmhfxi05kYFW9_9ewXA==/com.example.testlib-SckqPQJeKDtsvK2xuz9oBA==/base.apk!/lib/arm64-v8a/libmy_lib.so" is 32-bit instead of 64-bit

CMake输出日志 #

1> Command line: "C:\WINDOWS\system32\cmd.exe" /c "%SYSTEMROOT%\System32\chcp.com 65001 >NUL && "C:\PROGRAM FILES\MICROSOFT VISUAL STUDIO\2022\COMMUNITY\COMMON7\IDE\COMMONEXTENSIONS\MICROSOFT\CMAKE\CMake\bin\cmake.exe"  -G "Ninja"  -DCMAKE_BUILD_TYPE:STRING="Debug" -DCMAKE_INSTALL_PREFIX:PATH="C:/Users/danie/Documents/Workspace/gamechain-lib/out/install/android-arm64-debug" -DCMAKE_TOOLCHAIN_FILE:FILEPATH="C:/Program Files/Unity/Hub/Editor/2021.3.3f1/Editor/Data/PlaybackEngines/AndroidPlayer/NDK/build/cmake/android.toolchain.cmake"   -DCMAKE_MAKE_PROGRAM="C:\PROGRAM FILES\MICROSOFT VISUAL STUDIO\2022\COMMUNITY\COMMON7\IDE\COMMONEXTENSIONS\MICROSOFT\CMAKE\Ninja\ninja.exe" "C:\Users\kyo\Documents\Workspace\my-lib" 2>&1"
1> Working directory: C:/Users/kyo/Documents/Workspace/my-lib/out/build/android-arm64-debug
1> [CMake] -- ANDROID_PLATFORM not set. Defaulting to minimum supported version
1> [CMake] 16.
1> [CMake] -- Configuring done (0.0s)
1> [CMake] -- Generating done (0.0s)
1> [CMake] -- Build files have been written to: C:/Users/kyo/Documents/Workspace/my-lib/out/build/android-arm64-debug
1> Extracted CMake variables.
1> Extracted source files and headers.
1> Extracted code model.
1> Extracted toolchain configurations.
1> Extracted includes paths.

解决方案 #

关键原因 #

Android NDK工具链文件会在CMake配置阶段早期读取ANDROID_ABI等参数，而CMakeLists.txt中设置该变量的时机太晚，工具链已使用默认的32位架构（通常是armeabi-v7a）完成配置。必须在CMake启动配置前就传递这些参数。

修改CMakePresets.json #

在cacheVariables中添加ANDROID_ABI和可选的ANDROID_PLATFORM（指定minSdkVersion），修改后的配置片段：

{    
    "version": 3,    
    "configurePresets": [        
        {            
            "name": "android-arm64-debug",            
            "displayName": "Android Arm64 Debug",            
            "description": "Target Android with an Arm64 ABI.",            
            "generator": "Ninja",            
            "binaryDir": "${sourceDir}/out/build/${presetName}",            
            "installDir": "${sourceDir}/out/install/${presetName}",            
            "cacheVariables": { 
                "CMAKE_BUILD_TYPE": "Debug",
                "ANDROID_ABI": "arm64-v8a",
                "ANDROID_PLATFORM": "android-21" // 对应minSdkVersion 21，可按需调整
            },            
            "toolchainFile": "C:/Program Files/Unity/Hub/Editor/2021.3.3f1/Editor/Data/PlaybackEngines/AndroidPlayer/NDK/build/cmake/android.toolchain.cmake",            
            "condition": {                
                "type": "equals",                
                "lhs": "${hostSystemName}",                
                "rhs": "Windows"            
            },            
            "vendor": { "microsoft.com/VisualStudioRemoteSettings/CMake/2.0": { "remoteSourceRootDir": "$env{HOME}/.vs/$ms{projectDirName}" } }        
        },
        // 其他配置已省略 ...    
    ]
}

清理CMakeLists.txt中的无效代码 #

删除CMakeLists.txt中尝试设置ANDROID_ABI的代码块，避免冲突：

set(MY_LIB my_lib)

add_library(${MY_LIB} SHARED api.cpp)
target_link_libraries(${MY_LIB} core)
install(TARGETS ${MY_LIB}    
    RUNTIME DESTINATION bin    
    LIBRARY DESTINATION lib)

验证步骤 #

1. 删除旧的build目录（out/build/android-arm64-debug），清除缓存
2. 在Visual Studio中选择android-arm64-debug预设重新配置并编译
3. 用file命令检查生成的库：

   file libmy_lib.so
   

   输出应包含aarch64字样，确认是64位ARM架构库

内容的提问来源于stack exchange，提问作者Daniel Vernall