在使用jni调用时经常遇到数据类型转换问题，以下是char*与jstring相互转换的代码：
//java字符串转C字符串
char* jstringTostr(JNIEnv* env, jstring jstr)
{
char* pStr = NULL;
jclass jstrObj = (*env)->FindClass(env, "java/lang/String");
jstring encode = (*env)->NewStringUTF(env, "utf-8");
jmethodID methodId = (*env)->GetMethodID(env, jstrObj, "getBytes", "(Ljava/lang/String;)[B");
jbyteArray byteArray = (jbyteArray)(*env)->CallObjectMethod(env, jstr, methodId, encode);
jsize strLen = (*env)->GetArrayLength(env, byteArray);
jbyte *jBuf = (*env)->GetByteArrayElements(env, byteArray, JNI_FALSE);
if (jBuf > 0)
{
pStr = (char*)malloc(strLen + 1);
if (!pStr)
{
return NULL;
}
memcpy(pStr, jBuf, strLen);
pStr[strLen] = 0;
}
(*env)->ReleaseByteArrayElements(env, byteArray, jBuf, 0);
return pStr;
}
//C字符串转java字符串
jstring strToJstring(JNIEnv* env, const char* pStr)
{
int strLen = strlen(pStr);
jclass jstrObj = (*env)->FindClass(env, "java/lang/String");
jmethodID methodId = (*env)->GetMethodID(env, jstrObj, "", "([BLjava/lang/String;)V");
jbyteArray byteArray = (*env)->NewByteArray(env, strLen);
jstring encode = (*env)->NewStringUTF(env, "utf-8");
(*env)->SetByteArrayRegion(env, byteArray, 0, strLen, (jbyte*)pStr);
return (jstring)(*env)->NewObject(env, jstrObj, methodId, byteArray, encode);
}