Java web求解,急急急!!!!!!
我的JSP页面:
<body>
<form action="Ser" method="post">
<table  border="0" align="center" cellpadding="3" cellspacing="1" bgcolor="#006000">
   <tr bgcolor="#F8FFF7">
     <td colspan="2" bgcolor="#F8FFF7"><div align="center"><font size="4" color="#1D5C92">
       <input name="button222" type="submit" value=" 修改 ">
  </font> <font size="4" color="#1D5C92">
<input name="button24" type="button" value=" 返回 ">
</font></div>
  <tr bgcolor="#F6F6F6">
     <td width="78" nowrap bgcolor="#F8FFF7" class="td2">输入账号:</td>
     <td width="232" bgcolor="#F8FFF7"><input type="password" name="id"></td>
   </tr>
    <tr bgcolor="#F6F6F6">
     <td width="78" nowrap bgcolor="#F8FFF7" class="td2">输入原密码:</td>
     <td width="232" bgcolor="#F8FFF7"><input type="password" name="yuan"></td>
   </tr>
   <tr bgcolor="#F6F6F6">
     <td nowrap bgcolor="#F8FFF7" class="td2">输入新密码:</td>
     <td bgcolor="#F8FFF7"><input type="password" name="xin"></td>
   </tr>
   <tr bgcolor="#F6F6F6">
     <td nowrap bgcolor="#F8FFF7" class="td2">确认新密码:</td>
     <td bgcolor="#F8FFF7"><input type="password" name="que"></td>
   </tr>    
   <tr>
         <td align="center"><input type="submit" name="xiugai" value="修改"/></td>
         <td align="center"><input type="button" name="fanhui" value="返回"/></td>
   </tr>
</table>
</form>
</body>
我的数据连接类:
public class DBunit {		
	 private Connection con;		 	  
   public Connection getConn()
   {   try{Class.forName("com.mysql.jdbc.Driver");
	  }
	  catch(
ClassNotFoundException e){
		  System.out.print("加载驱动器有错误");
		  }
	  try{con=DriverManager.getConnection("jdbc:mysql://localhost/hr","gxp","gxp");	     
   }
  	  catch(
SQLException el){
  		  System.out.println("数据库连接有错误");
  	  }    	     	   
  	return con;
   }
   public void setConn(Connection con){
	  	this.con = con;
	  }
}
我的密码修改处理类:
public class Password {
	public String getString(String   s) {
         if(s==null)  
         { s= "";}  
         return   s;}
	public void pass(HttpServletRequest request)
	   throws SQLException, 
IOException, 
ServletException {
		// TODO Auto-generated method stub
		Str