总是出现这个错误java.lang.IllegalStateException: Cannot forward after response has been committed

请帮我解决解决
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8" import="demo.*,java.util.*,java.text.SimpleDateFormat"%><%
request.setCharacterEncoding("utf-8");
String userInputValidCode=request.getParameter("checkcode");
String realValidCode=(String)session.getAttribute("validateCode");
if (null==realValidCode){
request.getRequestDispatcher("./reg.jsp").forward(request, response);
}else{
boolean result=realValidCode.equalsIgnoreCase(userInputValidCode);
if (false==result){
request.setAttribute("errorMessage", "请输入正确的验证码!");
request.getRequestDispatcher("./reg.jsp").forward(request, response);
return;
}}
User user=new User();
user.setName(request.getParameter("name"));
user.setPass(request.getParameter("pass"));
user.setQuestion(request.getParameter("question"));
user.setQues_answer(request.getParameter("ques_answer"));
SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");
try{
Date s=sdf.parse(request.getParameter("birthday"));
user.setBirthday(s);
}catch(Exception e){
e.printStackTrace();
}
user.setSex(request.getParameter("sex"));
user.setNickName(request.getParameter("nickName"));
user.setEmail(request.getParameter("email"));
UserDao dao=new UserDao();
boolean isunique=dao.checkUser(user);
if(false==isunique){

request.setAttribute("errorMessage", "用户名不唯一,请重新输入!");
request.getRequestDispatcher("./reg.jsp").forward(request, response);
return;
}
boolean status=dao.saveUser(user);
if (true==status){
request.getRequestDispatcher("./index.html").forward(request, response);
return;
}else{
request.setAttribute("errorMessage", "保存数据失败,请检查输入!");
request.getRequestDispatcher("./reg.jsp").forward(request, response);
return;
}

%>

if (null==realValidCode){
request.getRequestDispatcher("./reg.jsp").forward(request, response);
return；//这里是不是少了一个return呢
}else{

这意思是说你已经做过响应了 就不能再在做forward跳转响应了 上代码看看