JNI参数传递|Surface

最新推荐文章于 2022-10-24 15:13:30 发布

stefzeus

最新推荐文章于 2022-10-24 15:13:30 发布

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文章标签： jni primitive reference class function access

本文链接：https://blog.youkuaiyun.com/stefzeus/article/details/6622011

版权

本文深入探讨JNI中关于Surface的参数传递，重点解析GetIntField方法的使用，揭示其在JNI与Java层交互中的关键作用。

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char* Get_Surface(JNIEnv *env, jclass cls, jobject param, int sdk_version)
{
        // Java层
        jfieldID surface = env->GetFieldID(cls, "mSurface", "Landroid/view/Surface;");
      jobject surface_cls = env->GetObjectField(param, surface);

        // Native层
    jclass surface_class = env->FindClass("android/view/Surface");
   jfieldID surface_native = env->GetFieldID(surface_class, "mSurface", "I"); //"I"指整型

        // the JNI also supports other functions such as GetIntField and SetFloatField for accessing instance fields of primitive types.
        return (char*)(Surface*)env->GetIntField(surface_cls, surface_native);

}

理解GetIntField

(char*)(Surface*)env->GetIntField(surface_cls, surface_native);

Once you have obtained the field ID, you can pass the object reference and the field ID to the appropriate instance field access function:

jstr = (*env)->GetObjectField(env, obj, fid);