android-gradle-plugin - Gradle : how to use BuildConfig in an android-library with a flag that gets set in an app

Question

我的基于(gradle 1.10 和 gradle 插件 0.8)的 android 项目包含一个大型 android 库，它依赖于 3 个不同的 android 应用程序

在我的图书馆中，我希望能够使用这样的结构

if (BuildConfig.SOME_FLAG) {
    callToBigLibraries()
}

因为 proguard 能够根据 SOME_FLAG 的最终值减小生成的 apk 的大小

但我不知道如何使用 gradle 来做到这一点:

* the BuildConfig produced by the library doesn't have the same package name than the app
* I have to import the BuildConfig with the library package in the library
* The apk of an apps includes the BuildConfig with the package of the app but not the one with the package of the library.

我尝试使用 BuildTypes 和类似的东西，但没有成功

release {
    // packageNameSuffix "library"
    buildConfigField "boolean", "SOME_FLAG", "true"
}
debug {
    //packageNameSuffix "library"
    buildConfigField "boolean", "SOME_FLAG", "true"
}

为我的库和应用程序构建共享 BuildConfig 的正确方法是什么？其标志将在应用程序中的构建时被覆盖？

Answer 1

作为解决方法，您可以使用此方法，该方法使用反射从应用程序(而不是库)获取字段值:

/**
 * Gets a field from the project's BuildConfig. This is useful when, for example, flavors
 * are used at the project level to set custom fields.
 * @param context       Used to find the correct file
 * @param fieldName     The name of the field-to-access
 * @return              The value of the field, or {@code null} if the field is not found.
 */
public static Object getBuildConfigValue(Context context, String fieldName) {
    try {
        Class<?> clazz = Class.forName(context.getPackageName() + ".BuildConfig");
        Field field = clazz.getField(fieldName);
        return field.get(null);
    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    } catch (NoSuchFieldException e) {
        e.printStackTrace();
    } catch (IllegalAccessException e) {
        e.printStackTrace();
    }
    return null;
}

例如，要获取 DEBUG 字段，只需从您的 Activity 中调用此字段即可:

boolean debug = (Boolean) getBuildConfigValue(this, "DEBUG");

我还在 AOSP Issue Tracker 上分享了这个解决方案.