关于servlet中调用数据库连接的有关问题,对数据库的操作老是无效,求

关于servlet中调用数据库连接的问题,对数据库的操作老是无效,求高手指点
我写了三个类,一个是customer类,一个是Register类(专门处理数据连接),一个是Check_validate类,用来判断一些逻辑,也引用了Register的方法
但是在Check_validate中的操作在数据库中一点反应也没有,求高手指点
package   BasementClass;
public   class   Customer{
private   String   Username;
private   String   Password;
private   String   Name;
private   String   Address;
private   String   E_mail;
public   Customer(String   Username,String   Password,String   Name,String   Address,String   E_mail){
this.Username=Username;
this.Password=Password;
this.Name=Name;
this.Address=Address;
this.E_mail=E_mail;
}
public   String   getUsername(){
return   Username;
}
public   String   getPassword(){
return   Password;
}
public   String   getName(){
return   Name;
}
public   String   getAddress(){
return   Address;
}
public   String   getE_mail(){
return   E_mail;
}
public   void   setUsername(String   username){
Username=username;
}
public   void   setPassword(String   password){
Password=password;
}
public   void   setName(String   name){
Name=name;
}
public   void   setAddress(String   address){
Address=address;
}
public   void   setE_mail(String   e_mail){
E_mail=e_mail;
}

}


package   Site_SQL;
import   BasementClass.*;

import   java.io.*;
import   javax.servlet.*;
import   javax.servlet.http.*;


public   class   Check_validate   extends   HttpServlet   {
String   user_name,pwd,re_pwd,address,name,email,note;
        Register   r;
        Customer   c;
          protected   void   doGet(HttpServletRequest   request,HttpServletResponse   response)
                              throws   ServletException,   IOException   {
                                      String   docType   =
" <!DOCTYPE   HTML   PUBLIC   \ "-//W3C//DTD   HTML   4.0   "+ "Transitional//EN\ "> \n ";

                                      response.setContentType( "text/html ");
                                      response.setCharacterEncoding( "UTF-8 ");
                                      PrintWriter   out   =   response.getWriter();
                                      user_name=request.getParameter( "user ");
                                      pwd=request.getParameter( "pwd ");
                                      re_pwd=request.getParameter( "re_pwd ");