从 Android 中的原生 c 返回 jbyteArray
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Returning jbyteArray from native c in Android
提问by Raneez Ahmed
I use native c to read data from an audio file to jbyte pointer. Now i want to send it to java as an jbyteArray.
我使用本机 c 从音频文件读取数据到 jbyte 指针。现在我想将它作为 jbyteArray 发送到 java。
jbyteArray Java_com_app_audio_player_readData(JNIEnv * env, jobject jobj,jstring readPath)
{
FILE *fin;
const char *inFile= (*env)->GetStringUTFChars(env,readPath,0);
fin = fopen(inFile, "r");
fseek(fin, 0, SEEK_END); // seek to end of file
int size = ftell(fin); // get current file pointer
fseek(fin, 0, SEEK_SET);
jbyte *data=(jbyte *)malloc(size*sizeof(jbyte));
int charCnt = 0;
charCnt=fread(data, 1, size, fin);
jbyteArray result=(*env)->NewByteArray(env, size);
//-- I want to convert data to jbyteArray and return it to java
fclose(fin);
return result;
}
How it is done?
它是如何完成的？
回答by violet313
use SetByteArrayRegion
用 SetByteArrayRegion
charCnt=fread(data, 1, size, fin);
jbyteArray result=(*env)->NewByteArray(env, size);
(*env)->SetByteArrayRegion(env, result, 0, size, data);
one could also use GetByteArrayElementseg:
也可以使用GetByteArrayElements例如：
jboolean isCopy;
jbyte* rawjBytes = (*env)->GetByteArrayElements(env, result, &isCopy);
//do stuff to raw bytes
memcpy(rawjBytes, data, size*sizeof(jbyte));
(*env)->ReleaseByteArrayElements(env, result, rawjBytes, 0);
see herefor more details on SetByteArrayRegion, GetByteArrayElementsand ReleaseByteArrayElements.
有关SetByteArrayRegion,GetByteArrayElements和 的更多详细信息，请参见此处ReleaseByteArrayElements。
NB:this question is probably a special case of this question
注意：这个问题可能是一个特例，这个问题
