我知道,调用一个JNI C法之类的名字吗? [英] Can I know the name of the class that calls a JNI C method?
问题描述
有没有什么办法可以知道叫JNI C code进行方法的类的名字吗?我可以用下面的语句获得对类的引用:
Is there any way I can know the name of the class that called a method in JNI C code ? I can obtain a reference to the class using the following statement :
jclass cls = (*env)->GetObjectClass(env,obj);
但有什么办法,我可以知道类的名字吗? 。
But is there any way I can know the name of the class ? .
推荐答案
这code会给你调用的类名称:
This code will give you the calling class name:
jclass cls = env->GetObjectClass(obj);
// First get the class object
jmethodID mid = env->GetMethodID(cls, "getClass", "()Ljava/lang/Class;");
jobject clsObj = env->CallObjectMethod(obj, mid);
// Now get the class object's class descriptor
cls = env->GetObjectClass(clsObj);
// Find the getName() method on the class object
mid = env->GetMethodID(cls, "getName", "()Ljava/lang/String;");
// Call the getName() to get a jstring object back
jstring strObj = (jstring)env->CallObjectMethod(clsObj, mid);
// Now get the c string from the java jstring object
const char* str = env->GetStringUTFChars(strObj, NULL);
// Print the class name
printf("\nCalling class is: %s\n", str);
// Release the memory pinned char array
env->ReleaseStringUTFChars(strObj, str);
请注意,我尚未采取任何行动来检查错误。这是描述如何能够做到只是一个小code片段。
Note that I haven't taken any actions to check for errors. This is just a small code snippet describing how it could be done.
另外,你可以做,而不是使用这个 GetStringUTFChars / ReleaseStringUTFChars
:
Alternatively you could do this instead of using the GetStringUTFChars/ReleaseStringUTFChars
:
// Make sure that the buffer is large enough
char str[128];
jint strlen = env->GetStringUTFLength(strObj);
env->GetStringUTFRegion(strObj, 0, strlen, str);
printf("\nCalling class is: %s\n", str);
没有必要因为字符串释放被复制到本地缓存。
No need to release since the string is copied to local buffer.
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