Android JNI char* 和jstring类型相互转换函数。

//jstring to char*

char* jstringTostring(JNIEnv* env, jstring jstr)

{

       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;

}

//char* to jstring

jstring stoJstring(JNIEnv* env, const char* pat)

{

       jclass strClass = env->FindClass("Ljava/lang/String;");

       jmethodID ctorID = env->GetMethodID(strClass, "<init>", "([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);

}