Web用户管理之修改密码

此页面为WebControl
alterpassword.ascx

<%@ Control Language="c#" AutoEventWireup="false"
            Codebehind="alterpassword.ascx.cs" Inherits="WebApplication1.control.alterpassword"
            TargetSchema="http://schemas.microsoft.com/intellisense/ie5" %>
<LINK href="../style/css.css" type="text/css" rel="stylesheet">
<form id="form_alterpassword" method="post" runat="server">
  <table id="table1" cellSpacing="0" cellPadding="0" width="600" align="center" border="0">
      <tr>
           <td class="contexttitle" vAlign="bottom" align="center" height="100">修改密码
                    <span id="Message" runat="server"></span></td>
      </tr>
      <tr>
           <td>
                <table cellSpacing="1" cellPadding="1" width="100%" align="center" border="0">
                    <tr>
                        <td align="center">用户名<label id="LableUser" runat="server"></label>
                        </td>
                    </tr>
                    <tr>
                        <td align="center">原密码
                            <asp:textbox id="TextBoxPassPre" Runat="server" MaxLength="16" TextMode="Password">
                              </asp:textbox><asp:requiredfieldvalidator id="Requiredfieldvalidator1"
                               runat="server" ErrorMessage="请填写" ControlToValidate="TextBoxPassPre">
                               </asp:requiredfieldvalidator></td>
                    </tr>
                    <tr>
                        <td align="center">新密码
                            <asp:textbox id="TextBoxPassNew" Runat="server" MaxLength="16" TextMode="Password">
                              </asp:textbox><asp:requiredfieldvalidator id="Requiredfieldvalidator2"
                              runat="server" ErrorMessage="请填写"
                              ControlToValidate="TextBoxPassNew"></asp:requiredfieldvalidator></td>
                    </tr>
                    <tr>
                        <td align="center">确认密码
                            <asp:textbox id="TextBoxPassNewConfirm" Runat="server" MaxLength="16" TextMode="Password">
                               </asp:textbox><asp:requiredfieldvalidator id="Requiredfieldvalidator3"
                               runat="server" ErrorMessage="请填写"
                               ControlToValidate="TextBoxPassNewConfirm"></asp:requiredfieldvalidator></td>
                    </tr>
                    <tr>
                        <td align="center"><font color="blue">请记住您的密码</font></td>
                    </tr>
                    <tr>
                        <td align="center"><asp:button id="Buttonsubmit" Runat="server" Width="100"
                                 Text="修改"></asp:button></td>
                    </tr>
                    <tr>
                        <td vAlign="middle" align="center" height="220">
                            <P><FONT color="#0000ff"><asp:comparevalidator id="CompareValidator1"
                                     runat="server" ErrorMessage="两次输入的新密码不一致，请重新输入"
                                    ControlToValidate="TextBoxPassNewConfirm"
                                  ControlToCompare="TextBoxPassNew"></asp:comparevalidator></FONT></P>
                        </td>
                    </tr>
                </table>
            </td>
        </tr>
    </table>
</form>

alterpassword.ascx.cs

namespace WebApplication1.control
{
    using System;
    using System.Data;
    using System.Drawing;
    using System.Web;
    using System.Web.UI.WebControls;
    using System.Web.UI.HtmlControls;
    using System.Data.SqlClient;
    using System.Text;

    /**//// <summary>
    ///        alterpassword 的摘要说明。
    /// </summary>
    public class alterpassword : System.Web.UI.UserControl
    {
        protected System.Web.UI.WebControls.Button Buttonsubmit;
        protected System.Web.UI.WebControls.TextBox TextBoxPassPre;
        protected System.Web.UI.HtmlControls.HtmlGenericControl LableUser;
        protected System.Web.UI.WebControls.TextBox TextBoxPassNew;
        protected System.Web.UI.WebControls.RequiredFieldValidator Requiredfieldvalidator1;
        protected System.Web.UI.WebControls.RequiredFieldValidator Requiredfieldvalidator2;
        protected System.Web.UI.WebControls.TextBox TextBoxPassNewConfirm;
        protected System.Web.UI.WebControls.RequiredFieldValidator Requiredfieldvalidator3;
        protected System.Web.UI.WebControls.CompareValidator CompareValidator1;
        protected System.Data.SqlClient.SqlConnection sqlConnection1;
        protected System.Data.SqlClient.SqlCommand sqlCommand1;
        protected System.Web.UI.HtmlControls.HtmlGenericControl Message;

        private void Page_Load(object sender, System.EventArgs e)
        {
            // 在此处放置用户代码以初始化页面
            if(string.Empty==((control.User)(this.Session["user"])).UserName)
            {
                System.Configuration.AppSettingsReader asr=new System.Configuration.AppSettingsReader();
                string strURLPre=((string)(asr.GetValue("urllocation",typeof(string))));
                this.Response.Redirect(strURLPre+"index.aspx",true);
                this.Response.End();
            }
        }

        Web 窗体设计器生成的代码#region Web 窗体设计器生成的代码
        override protected void OnInit(EventArgs e)
        {
            //
            // CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。
            //
            InitializeComponent();
            base.OnInit(e);
        }
        
        /**//// <summary>
        ///        设计器支持所需的方法 - 不要使用代码编辑器
        ///        修改此方法的内容。
        /// </summary>
        private void InitializeComponent()
        {
            System.Configuration.AppSettingsReader configurationAppSettings = new System.Configuration.AppSettingsReader();
            this.sqlConnection1 = new System.Data.SqlClient.SqlConnection();
            this.sqlCommand1 = new System.Data.SqlClient.SqlCommand();
            this.Buttonsubmit.Click += new System.EventHandler(this.Buttonsubmit_Click);
            // 
            // sqlConnection1
            // 
            this.sqlConnection1.ConnectionString = ((string)(configurationAppSettings.GetValue("connectString", 
                     typeof(string))));
            // 
            // sqlCommand1
            // 
            this.sqlCommand1.Connection = this.sqlConnection1;
            this.Load += new System.EventHandler(this.Page_Load);

        }
        #endregion

        private void Buttonsubmit_Click(object sender, System.EventArgs e)
        {
            string strUser=((control.User)(this.Session["user"])).UserName;
            string strPassPre=this.TextBoxPassPre.Text.Trim();
            Encoding ascii=Encoding.ASCII;
            byte[] data=ascii.GetBytes(strPassPre);
            System.Security.Cryptography.MD5 md5=
                     new System.Security.Cryptography.MD5CryptoServiceProvider();
            byte[] result=md5.ComputeHash(data);
            string pwdmd5=Convert.ToBase64String(result);
            this.sqlCommand1.CommandText="select * from tbuser where username='"+
                strUser+"' and userpwd='"+pwdmd5+"'";
            try
            {
                this.sqlConnection1.Open();
                SqlDataReader dr=this.sqlCommand1.ExecuteReader();
                if(dr.HasRows)
                {
                    dr.Read();
                    System.Data.SqlTypes.SqlGuid guid=new System.Data.SqlTypes.SqlGuid(dr["id"].ToString());
                    this.sqlConnection1.Close();
                    data=ascii.GetBytes(this.TextBoxPassNew.Text.Trim());
                    result=md5.ComputeHash(data);
                    pwdmd5=Convert.ToBase64String(result);
                    this.sqlCommand1.CommandText="Update tbuser Set userpwd='"+pwdmd5+"' Where id='"+guid+"'";
                    this.sqlConnection1.Open();
                    this.sqlCommand1.ExecuteNonQuery();
                    this.Message.InnerHtml="<br><font size='4' color='blue'>修改成功</font>";
                }
                else
                {
                    this.Message.InnerHtml="<br><font size='4' color='red'>原密码错误，密码不能修改</font>";
                }
            }
            catch(SqlException Ex)
            {
                this.Message.InnerHtml="<br><font size='4' color='red'>错误："+Ex.Message+"</font>";
            }
            finally
            {
                this.sqlCommand1.Dispose();
                this.sqlConnection1.Close();
            }
        }
    }
}

Ja注：
数据库中的tbuser表结构，请参看 
       Web用户管理之用户注册 http://www.cnblogs.com/ja/articles/31239.aspx