我想要来自 ndk 库的 different string value。 因为我有两种 flavor 的演示和现场直播，所以我想要值“你好，我来自演示”，用于演示 flavor ，而对于现场 flavor ，我想要“你好，我来自现场”

这是我的java文件代码

public class MainActivity extends AppCompatActivity {
    // Used to load the 'native-lib' library on application startup.
    static {
        System.loadLibrary("native-lib");
    }

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    // Example of a call to a native method
    TextView tv = (TextView) findViewById(R.id.sample_text);
    tv.setText(stringFromJNI());
}

/**
 * A native method that is implemented by the 'native-lib' native library,
 * which is packaged with this application.
 */
public native String stringFromJNI();

这是我的cpp文件代码

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

extern "C"
JNIEXPORT jstring JNICALL
Java_com_de_demo_ndk2_MainActivity_stringFromJNI(
        JNIEnv *env,
        jobject /* this */) {
    std::string hello = "hello I am from  demo";
    return env->NewStringUTF(hello.c_str());
}

这是我的build.gradle文件

apply plugin: 'com.android.application'

android {
    compileSdkVersion 26
    defaultConfig {
        applicationId "com.de.demo.ndk2"
        minSdkVersion 15
        targetSdkVersion 26
        versionCode 1
        flavorDimensions "default"
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
        externalNativeBuild {
            cmake {
                cppFlags ""
            }
        }
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
    productFlavors {

        demo
                {
                    // applicationId "com.readwhere.whitelabel.test"
                    //applicationId "com.android.rwstaging"
                    applicationId "com.android.demo"
                    versionName "2.1"
                    dimension "default"

                    externalNativeBuild {
                        cmake {

                            targets "native-lib-demo","my-executible-                   demo"

                        }}


                }
        live
                {
                    // applicationId "com.readwhere.whitelabel.test"
                    //applicationId "com.android.rwstaging"
                    applicationId "com.android.live"
                    versionName "2.1"
                    dimension "default"



                }}
    externalNativeBuild {
        cmake {
            path "CMakeLists.txt"
        }
    }
}

我在演示文件夹和主文件夹中粘贴了相同的 cpp 文件 但可以完成我的任务。任何帮助将不胜感激 这是一些引用链接

https://developer.android.com/studio/projects/gradle-external-native-builds.html

How to set CmakeLists path in product flavor for each Android ABI?

最佳答案

可能，在编译时实现您的目标的最少代码是根据口味设置 cppFLags:

productFlavors {
  demo {
    applicationId "com.android.demo"
    versionName "2.1"
    dimension "default"

    externalNativeBuild.cmake {
      cppFlags '-DDEMO'
    }
  }
  live {
     applicationId "com.android.live"
     versionName "2.1"
     dimension "default"
    externalNativeBuild.cmake {
      cppFlags '-DLIVE'
    }
  }
}

在你的cpp文件中

#ifdef DEMO
  std::string hello = "hello I am from demo";
#endif
#ifdef LIVE
  std::string hello = "hello I am from live";
#endif

或者您可以使用 stingify这样的模式 answer .

当然，您的条件编译不限于字符串变化。

关于java - NDK 支持不同的 Product Flavor，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/47350245/