JNI基本数据类型转换

/*******************************************************************
*char*----->jstring
*******************************************************************/
jstring c2js( const char* pat)
{
   JNIEnv* env = AndroidRuntime::getJNIEnv();
   jclass strClass = env->FindClass("java/lang/String");
   jmethodID ctorID = env->GetMethodID(strClass, "",
           "([BLjava/lang/String;)V");
   jbyteArray bytes = env->NewByteArray(strlen(pat));
   env->SetByteArrayRegion(bytes, 0, strlen(pat), (jbyte*) pat);
   jstring encoding = env->NewStringUTF("utf-8");
   return (jstring) env->NewObject(strClass, ctorID, bytes, encoding);
}
/******************************************************************
*jstring ----->char*
********************************************************************/
char* js2c( jstring jstr)
{
   JNIEnv* env = AndroidRuntime::getJNIEnv();
   char* rtn = NULL;
   jclass clsstring = env->FindClass("java/lang/String");
   jstring strencode = env->NewStringUTF("utf-8");
   jmethodID mid = env->GetMethodID(clsstring, "getBytes",
           "(Ljava/lang/String;)[B");
   jbyteArray barr = (jbyteArray) env->CallObjectMethod(jstr, mid, strencode);
   jsize alen = env->GetArrayLength(barr);
   jbyte* ba = env->GetByteArrayElements(barr, JNI_FALSE);
   if (alen > 0)
   {
       rtn = (char*) malloc(alen + 1);
       memcpy(rtn, ba, alen);
       rtn[alen] = 0;
   }
   env->ReleaseByteArrayElements(barr, ba, 0);
   return rtn;
}
/*****************************************************************
*wchar_t* ----->jstring
*******************************************************************/
jstring w2js( wchar_t* str)
{
   JNIEnv* env = AndroidRuntime::getJNIEnv();
   size_t len = wcslen(str);
   jchar* str2 = (jchar*) malloc(sizeof(jchar) * (len + 1));
   int i;
   for (i = 0; i < len; i++)
       str2[i] = str[i];
   str2[len] = 0;
   jstring js = env->NewString(str2, len);
   free(str2);
   return js;
}

/*****************************************************************
*XWCHAR* ----->jstring
*******************************************************************/
jstring xw2js( XWCHAR* str)
{
   JNIEnv* env = AndroidRuntime::getJNIEnv();
   size_t len = gg_wcslen(str);
   jchar* str2 = (jchar*) malloc(sizeof(jchar) * (len + 1));
   int i;
   for (i = 0; i < len; i++)
       str2[i] = str[i];
   str2[len] = 0;
   jstring js = env->NewString(str2, len);
   free(str2);
   return js;
}

/******************************************************************
*jstring----->wchar_t*
********************************************************************/
wchar_t* js2w( jstring str)
{
   JNIEnv* env = AndroidRuntime::getJNIEnv();
   int len = env->GetStringLength(str);
   wchar_t *w_buffer = new wchar_t[len];
   memset(w_buffer, 0, len + 1);
   w_buffer[len] = '\0';
   wcsncpy(w_buffer, (wchar_t *) env->GetStringChars(str, 0), len);
   env->ReleaseStringChars(str, (const unsigned short *) w_buffer);
   return w_buffer;
}

/******************************************************************
*jstring----->XWCHAR*
********************************************************************/
XWCHAR* js2xw( jstring str)
{
   JNIEnv* env = AndroidRuntime::getJNIEnv();

   int len = env->GetStringLength(str);

   XWCHAR *w_buffer = new XWCHAR[len + 1];
   memset(w_buffer, 0, (len+1) * 2 );

   const jchar* tmp = env->GetStringChars(str, false);
   memcpy(w_buffer, tmp, len * 2 );

   env->ReleaseStringChars(str, tmp);

   return w_buffer;
}

char* ------------> jbyteArray

   jbyteArray RtnArr = NULL; //下面一系列操作把btPath转成jbyteArray 返回出去
    RtnArr =env->NewByteArray(strlen(btPath));
    env->SetByteArrayRegion(RtnArr, 0, strlen(btPath), (jbyte*)btPath );

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