编译Android-Object-Detection项目遇CMake编译工具未设置错误求助

问题描述 #

我最近在尝试编译开源项目Android-Object-Detection，折腾了好长时间都没法成功构建，每次都会触发CMake错误。我查过StackOverflow上的相关解答，但可能是自己对JNI和原生编译流程不太熟，没解决问题。我是JNI新手，对原生编译这块了解有限，以下是我遇到的错误信息：

Build command failed. Error while executing '/home/rudra/Android/Sdk/cmake/3.6.4111459/bin/cmake' with arguments {-H/home/rudra/Downloads/Projects/CVTEST/Android-Object-Detection-master/app -B/home/rudra/Downloads/Projects/CVTEST/Android-Object-Detection-master/app/.externalNativeBuild/cmake/release/armeabi -GAndroid Gradle - Ninja -DANDROID_ABI=armeabi -DANDROID_NDK=/home/rudra/Android/Sdk/ndk-bundle -DCMAKE_LIBRARY_OUTPUT_DIRECTORY=/home/rudra/Downloads/Projects/CVTEST/Android-Object-Detection-master/app/build/intermediates/cmake/release/obj/armeabi -DCMAKE_BUILD_TYPE=Release -DCMAKE_MAKE_PROGRAM=/home/rudra/Android/Sdk/cmake/3.6.4111459/bin/ninja -DCMAKE_TOOLCHAIN_FILE=/home/rudra/Android/Sdk/ndk-bundle/build/cmake/android.toolchain.cmake -DANDROID_NATIVE_API_LEVEL=21 -DCMAKE_CXX_FLAGS=-fexceptions} -- Configuring incomplete, errors occurred! (include) CMakeLists.txt Open File CMake Error: CMAKE_C_COMPILER not set, after EnableLanguage CMake Error: CMAKE_CXX_COMPILER not set, after EnableLanguage Build command failed. Error while executing '/home/rudra/Android/Sdk/cmake/3.6.4111459/bin/cmake' with arguments {-H/home/rudra/Downloads/Projects/CVTEST/Android-Object-Detection-master/app -B/home/rudra/Downloads/Projects/CVTEST/Android-Object-Detection-master/app/.externalNativeBuild/cmake/debug/armeabi -GAndroid Gradle - Ninja -DANDROID_ABI=armeabi -DANDROID_NDK=/home/rudra/Android/Sdk/ndk-bundle -DCMAKE_LIBRARY_OUTPUT_DIRECTORY=/home/rudra/Downloads/Projects/CVTEST/Android-Object-Detection-master/app/build/intermediates/cmake/debug/obj/armeabi -DCMAKE_BUILD_TYPE=Debug -DCMAKE_MAKE_PROGRAM=/home/rudra/Android/Sdk/cmake/3.6.4111459/bin/ninja -DCMAKE_TOOLCHAIN_FILE=/home/rudra/Android/Sdk/ndk-bundle/build/cmake/android.toolchain.cmake -DANDROID_NATIVE_API_LEVEL=21 -DCMAKE_CXX_FLAGS=-fexceptions} -- Configuring incomplete, errors occurred! (include) CMakeLists.txt Open File CMake Error: CMAKE_C_COMPILER not set, after EnableLanguage CMake Error: CMAKE_CXX_COMPILER not set, after EnableLanguage

解决方案 #

你遇到的核心问题是CMake找不到C/C++编译器，这大概率和工具版本不兼容、架构废弃或者缓存混乱有关，试试下面这些步骤：

• 更新CMake和NDK到兼容版本
  你当前用的CMake 3.6版本太老了，和ndk-bundle的兼容性很差。打开Android Studio的SDK管理器，把CMake更新到3.18以上的稳定版本，同时确认NDK版本也更新到较新的稳定版（比如25.x系列），并在app模块的build.gradle里指定对应的版本：

  android {
      ndkVersion "25.1.8937393" // 替换成你安装的NDK版本
      externalNativeBuild {
          cmake {
              path "CMakeLists.txt"
              version "3.18.1" // 替换成你安装的CMake版本
          }
      }
  }
  

• 废弃armeabi架构，改用支持的ABI
  从NDK r17开始，armeabi架构已经被官方废弃，工具链不再提供对应的编译器。修改app模块build.gradle里的abi配置：

  android {
      defaultConfig {
          ndk {
              abiFilters "armeabi-v7a", "arm64-v8a"
          }
      }
  }
  

• 手动指定编译器路径（如果更新后仍不行）
  打开项目的CMakeLists.txt，在文件最开头添加以下代码，手动指定NDK里的clang编译器路径（注意替换成你系统对应的路径，比如Windows是windows-x86_64，macOS是darwin-x86_64）：

  set(CMAKE_C_COMPILER "${ANDROID_NDK}/toolchains/llvm/prebuilt/linux-x86_64/bin/clang")
  set(CMAKE_CXX_COMPILER "${ANDROID_NDK}/toolchains/llvm/prebuilt/linux-x86_64/bin/clang++")
  

• 清理缓存后重新构建
  先通过Android Studio的File -> Invalidate Caches...清理IDE缓存，然后删除项目根目录下的.externalNativeBuild和build文件夹，最后点击Sync Project with Gradle Files，再尝试重新构建。旧缓存经常会导致配置冲突。

内容的提问来源于stack exchange，提问作者Diaz diaz