安插数据库出错，新手求教

插入数据库出错，新手求教
错误是：The server encountered an internal error () that prevented it from fulfilling this request.

exception  

java.lang.NullPointerException
 cn.wy.CtrlServlet.Reg.processRequest(Reg.java:63)
 cn.wy.CtrlServlet.Reg.doPost(Reg.java:86)
 javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
 javax.servlet.http.HttpServlet.service(HttpServlet.java:717)


note The full stack trace of the root cause is available in the Apache Tomcat/6.0.35 logs.
源码：
DBConnection dbc=null;
  String userEmail;
  String userName;
  String userPwd;
  //int userSex;
  //Date userbirthday = null;
  //String userSchool;
  response.setContentType("text/html;charset=UTF-8");  
  out = response.getWriter();
  try{ dbc = new DBConnection();  
  PreparedStatement ps = null;  
  userEmail = request.getParameter("userEmail");  
  userName = request.getParameter("userName");  
  userPwd = request.getParameter("userPwd");
  System.out.print(userEmail);
  System.out.print(userName);
  System.out.print(userPwd);
  //userSex = Integer.parseInt(request.getParameter("userSex"));  
   
  //userSchool = request.getParameter("userSchool");  
  if (userName != null && userPwd != null && userEmail != null)
  {
  ps = dbc.getCon().prepareStatement("insert into ceshi (userEmail,userName,userPwd)" +" values(?,?,?)"); 
  ps.setString(1, userEmail);  
  ps.setString(2, userName);  
  ps.setString(3, userPwd);  
// //ps.setDate(5, userbirthday);  
  //ps.setInt(4, userSex);  
  ps = dbc.getCon().prepareStatement("insert into ceshi values(userEmail,userName,userPwd)");
  ps.execute();
  System.out.print("新用户注册：" + request.getParameter("userName") + " ");
  out.print("<script>alert('恭喜您：注册成功！现已经登录到网站！');history.go(-1)</script>");
  }
  if (dbc != null)  
  dbc.dbClose();
  }
  catch(SQLException ex)
  { out.print("<script>alert('注册失败！数据库连接错误！');history.go(-1)</script>");  
  ex.printStackTrace();  
  if (dbc != null)  
  dbc.dbClose(); }
  }


------解决方案--------------------------------------------------------
施主...调试下吧...明显告诉你是NullPointerException ...
------解决方案--------------------------------------------------------
或者重启去吧
------解决方案--------------------------------------------------------
空指针异常cn.wy.CtrlServlet.Reg.processRequest(Reg.java:63)63行，分析下吧，别人帮不了你
------解决方案--------------------------------------------------------
首先，看你要写的几个值打印出来都不是null
其次，看看你数据库字段设的属性是什么，是否长度不够
------解决方案--------------------------------------------------------
看看这行附近的变量在使用前是不是忘记赋值了。

cn.wy.CtrlServlet.Reg.processRequest(Reg.java:63)

空指针异常 基本上都是这个原因。
------解决方案--------------------------------------------------------
空指针异常 跟踪一下你的代码 应该很快就解决了 。。