Servlet 转发问题

XML中的配置
  <servlet-mapping>
    <servlet-name>UserRegistServlet</servlet-name>
    <url-pattern>/UserRegistServlet</url-pattern>
  </servlet-mapping>
  
  <servlet-mapping>
    <servlet-name>UserLonginServlet</servlet-name>
    <url-pattern>/UserLonginServlet</url-pattern>
  </servlet-mapping>AJAX请求Servlet
        ......
xmlHttp.onreadystatechange=callBack;
xmlHttp.open("post","UserRegistServlet?rel="+rel,true);
xmlHttp.send(null);Servlet doPost方法代码 public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {

Logger logger=Logger.getLogger(UserRegistServlet.class.getName());
response.setContentType("text/html;charset=GBK");
PrintWriter out = response.getWriter();
HttpSession session=request.getSession();
UseInfo registInfo=new UseInfo();
String userRegist=GBK.check(request.getParameter("rel"));//得到注册页面数据(Json类型)
String codeNum=null;
try {
JSONObject UserRegist=new JSONObject(userRegist); // 将Json类型转换成Object类型
codeNum=UserRegist.getString("codeNum");
if(!(codeNum.equals(session.getAttribute("codeNum")))){
//判断注册页面验证码是否正确
out.println("codeNumsuccess");
}else{
//通过Json获得注册页面的数据并保存到java Bean 中
logger.debug("正在往 javaben 插入数据");
registInfo.setU_userNum(UserRegist.getString("userNum"));
registInfo.setU_pwd(UserRegist.getString("pwd"));
registInfo.setU_question(UserRegist.getString("question"));
registInfo.setU_key(UserRegist.getString("key"));
registInfo.setU_name(UserRegist.getString("name"));
registInfo.setU_carNum(UserRegist.getString("carNum"));
registInfo.setU_post(UserRegist.getString("post"));
registInfo.setU_schoolNum(UserRegist.getString("schoolNum"));
registInfo.setU_phone(UserRegist.getString("phone"));
registInfo.setU_email(UserRegist.getString("email"));
registInfo.setU_provinces(UserRegist.getString("provinces"));
registInfo.setU_city(UserRegist.getString("city"));
registInfo.setU_address(UserRegist.getString("address"));
registInfo.setU_postNum(UserRegist.getString("postNum"));
logger.debug("往 javaben 插入数据成功！");
RegistSQL registSQL=new RegistSQL();
boolean flag=registSQL.RegistResult(registInfo);
if(flag){
//见用户名字和会员号保存 在注册成功页面取出
session.setAttribute("name",registInfo.getU_name());
session.setAttribute("userNum", registInfo.getU_userNum());
// RequestDispatcher dispatcher=request.getRequestDispatcher("/registSuccess.jsp");
//dispatcher.forward(request, response);
//response.sendRedirect("registSuccess.jsp");
request.getRequestDispatcher("registSuccess.jsp").forward(request, response);
System.out.println("转到了registSuccess页面");
}else{
out.println("false");
}
}
} catch (JSONException e) {

e.printStackTrace();
}

}
数据库插入成功 System.out.println("转到了registSuccess页面"); 这句页执行了