急救！！！！！！！！！！

1：登录的Servlet,获取当前登录的ID
package com.sorfteem.informationsystem.welcomeservlet;import java.io.IOException;import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;import com.sorfteem.informationsystem.dao.UserDAO;
import com.sorfteem.informationsystem.dto.UserDTO;public class WelcomeServlet extends HttpServlet { @Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
// TODO Auto-generated method stub
doPost(req, resp);
} @Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
// TODO Auto-generated method stub
req.setCharacterEncoding("utf-8");
String name=req.getParameter("username");
String password=req.getParameter("password");
UserDTO dto=new UserDTO(name,password);
UserDAO  dao=new UserDAO();
UserDTO flag=dao.validate(dto);
if (flag!=null) {

HttpSession session=req.getSession();
session.setAttribute("isUser", flag);
System.out.println(((UserDTO)session.getAttribute("isUser")).getId());
req.getRequestDispatcher("welcome.jsp").forward(req, resp);
}else{
resp.sendRedirect("login.jsp");
}
}
  
}
2： 增加一条记录的dao
public class ContactDAO {
Connection conn=null;
PreparedStatement ps=null;
ResultSet rs=null;
public void add(ContactDTO dto,UserDTO user_id){
conn=GetConnection.getConnection();
String sql="insert into tongxun(id,user_id,name,sex,mobile,Email,QQ,Work,Address,zip)value(null,?,?,?,?,?,?,?,?,?)";
try {
ps=conn.prepareStatement(sql);
ps.setInt(1, dto.getId());
ps.setInt(2, dto.getUser_id());
ps.setString(3, dto.getName());
ps.setString(4, dto.getSex());
ps.setString(5, dto.getMobile());
ps.setString(6, dto.getEmail());
ps.setString(7, dto.getQQ());
ps.setString(8, dto.getWork());
ps.setString(9, dto.getAddress());
ps.setString(10, dto.getZip());
boolean s=ps.execute();
System.out.println(s);
ps.close();
conn.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}3:传到添加的处理数据的Servlet中
package com.sorfteem.informationsystem.tongxunservlet;import java.io.IOException;
import java.io.PrintWriter;import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;import com.sorfteem.informationsystem.dao.ContactDAO;
import com.sorfteem.informationsystem.dto.ContactDTO;
import com.sorfteem.informationsystem.dto.UserDTO;public class AddressServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request,response); }
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setCharacterEncoding("utf-8");
String ids=request.getParameter("user_id");
String name=request.getParameter("name");
String sex=request.getParameter("sex");
String Mobile=request.getParameter("mobile");
String Email=request.getParameter("email");
String QQ=request.getParameter("qq");
String Work=request.getParameter("company");
String Address=request.getParameter("address");
String zip=request.getParameter("postcode");
ContactDAO  dao=new ContactDAO();
UserDTO user_id=(UserDTO) request.getSession().getAttribute("isUser");
ContactDTO dto=new ContactDTO(name,sex,Mobile,Email,QQ,Work,Address,zip);
dto.setId(Integer.parseInt(ids));
dao.add(dto,user_id);
request.getRequestDispatcher("Address_addServlet").forward(request, response);

}}
 为什么传不进去值 是空的 谁帮我解决下