char*   Jstring2CStr(JNIEnv*   env,   jstring   jstr){     char*   rtn   =   NULL;     jclass   clsstring   =   (*env)->FindClass(env,"java/lang/String");     jstring   strencode   =   (*env)->NewStringUTF(env,"GB2312");     jmethodID   mid   =   (*env)->GetMethodID(env,clsstring,   "getBytes",   "(Ljava/lang/String;)[B");     jbyteArray   barr=   (jbyteArray)(*env)->CallObjectMethod(env,jstr,mid,strencode); // String .getByte("GB2312");     jsize   alen   =   (*env)->GetArrayLength(env,barr);     jbyte*   ba   =   (*env)->GetByteArrayElements(env,barr,JNI_FALSE);     if(alen   >   0)     {      rtn   =   (char*)malloc(alen+1);         //"\0"      memcpy(rtn,ba,alen);      rtn[alen]=0;     }     (*env)->ReleaseByteArrayElements(env,barr,ba,0);  //     return rtn;}