Set Android.mk flag through Gradle depending on build type

问题

I need to set a flag inside Android.mk file which tells to the C code whether it's debug mode or not.

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)

The problem is that I often forget to change the value when building a release and viceversa so I'm looking forward to a way that does it automatically.

I tried changing Android.mk to:

LOCAL_CFLAGS := -DDEBUG_MODE

And changed the build.gradle to the following:

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
}

This was not enough, the flag is not changing depending on build type. I found few information about this and the above code is the result of what I read on the internet. Do you have any suggestion about how to get it to work properly?

回答1:

Use externalNativeBuild { ndkBuild { within the build type. Note that the flags will be added to APP_CFLAGS (i.e. all modules), not LOCAL_CFLAGS.

build.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)

native-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());
}

回答2:

You can do it in you Application.mk file with just these few lines.

## DEBUG MODE
APP_ABI := armeabi-v7a  #Add your target ABI's or change, it's up to you.
APP_CFLAGS += -UNDEBUG -O0 -g -ggdb 
APP_OPTIM := debug
APP_CPPFLAGS += -DDMZ_DEBUG=1

来源：https://stackoverflow.com/questions/44084950/set-android-mk-flag-through-gradle-depending-on-build-type

标签

android

android-ndk

android-gradle-plugin

build.gradle