根据构建类型通过 Gradle 设置 Android.mk 标志

我需要在里面设置一个标志Android.mk文件告诉 C 代码是否处于调试模式。

LOCAL_MODULE := auth
LOCAL_SRC_FILES := auth.c
LOCAL_CFLAGS := -DDEBUG_MODE=0
LOCAL_EXPORT_CFLAGS := $(LOCAL_CFLAGS)
LOCAL_LDLIBS := -llog
LOCAL_C_INCLUDES := auth.h

include $(BUILD_SHARED_LIBRARY)

问题是我经常忘记在构建版本时更改值，反之亦然，因此我期待一种自动执行此操作的方法。

我尝试改变Android.mk to:

LOCAL_CFLAGS := -DDEBUG_MODE

并改变了build.gradle至以下内容：

android {
    compileSdkVersion 25
    buildToolsVersion "25.0.2"
    defaultConfig {
        minSdkVersion 16
        targetSdkVersion 25
    }

    buildTypes {
        release {
            debuggable false
            minifyEnabled true
            shrinkResources true
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
            ndk {
                cFlags = " -DDEBUG_MODE=0 "
            }
        }
        debug {
            debuggable true
            minifyEnabled false
            shrinkResources false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
            ndk {
                cFlags = " -DDEBUG_MODE=1 "
            }
        }
    }

    sourceSets.main {
        jni.srcDirs = ['src/main/none']
        jniLibs.srcDirs = ["src/main/libs"]
    }

    externalNativeBuild {
        ndkBuild {
            path 'src/main/jni/Android.mk'
        }
    }
    return void
}

这还不够，标志不会根据构建类型而改变。我发现了一些关于此的信息，上面的代码是我在互联网上阅读的结果。 您对如何使其正常工作有什么建议吗？

Use externalNativeBuild { ndkBuild {在构建类型内。请注意，标志将被添加到APP_CFLAGS（即所有模块），而不是LOCAL_CFLAGS.

构建.gradle：

android {
    compileSdkVersion 25
    buildToolsVersion "25.0.2"
    defaultConfig {
        applicationId "com.example.ndkbuildtest"
        minSdkVersion 21
        targetSdkVersion 25
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
        externalNativeBuild {
            ndkBuild {
                abiFilters "armeabi-v7a"
                arguments "APP_STL:=gnustl_static"
                cppFlags "-std=c++11","-frtti","-fexceptions"
            }
        }
    }
    buildTypes {
        release {
            externalNativeBuild {
                ndkBuild {
                    cFlags "-DDEBUG_MODE=0"
                }
            }
        }
        debug {
            externalNativeBuild {
                ndkBuild {
                    cFlags "-DDEBUG_MODE=1"
                }
            }
        }
    }
    externalNativeBuild {
        ndkBuild {
            path "Android.mk"
        }
    }
}

Android.mk：

LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)

LOCAL_MODULE := native-lib
LOCAL_SRC_FILES := src/main/cpp/native-lib.cpp
include $(BUILD_SHARED_LIBRARY)

本机lib.cpp：

#include <jni.h>
#include <string>

#if DEBUG_MODE
#error "Debug mode enabled!
#endif

extern "C"
JNIEXPORT jstring JNICALL
Java_com_example_ndkbuildtest_MainActivity_stringFromJNI(
        JNIEnv *env,
        jobject /* this */) {
    std::string hello = "Hello from C++";
    return env->NewStringUTF(hello.c_str());
}