验证码的显示

protected void Page_Load(object sender, EventArgs e)
       {
           try
           {
               if (!this.IsPostBack)
               {
                   this.ViewState["GUID"] = System.Guid.NewGuid().ToString();
                   this.lblGUID.Text = this.ViewState["GUID"].ToString();
                       }
           catch
           {
           }
       }

<asp:Label ID="lblGUID" runat="server" Text="Label" Style="display: none"></asp:Label>

<a id="A2" href="" onclick="ChangeCode('ImageCheck','lblGUID','Opanel/ValidateCode.aspx');return false;">
                                        <asp:Image ID="ImageCheck" runat="server" ImageAlign="AbsMiddle" ImageUrl="Opanel/ValidateCode.aspx?GUID=GUID"
                                            ToolTip="看不清，换一个" Height="26px" />
                                    </a>

第一次加载时把GUID 的值写好了。

然后赋给一个页面的隐藏控件，用于存储这个值。以后再onclick这个验证码时。我们就可以直接取值了。

System.Guid.NewGuid().ToString();
全球唯一标识

/// <summary>
        /// 验证码验证
        /// </summary>
        private Boolean CheckCode()
        {
            if (Request["checkCode"].ToString().ToLower() == Session["checkCode"].ToString().ToLower())
            {
                return true;
            }
            else
            {
                return false;
            }
        }