jstring和char*之間的轉(zhuǎn)換方法

//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;
    }