How to specify a value to password , PasswordBox Control

How to save textbox viewstate that modetype is password, Show password

<asp:TextBox runat="server" ID="txtPassword" TextMode="Password" Value='<%#Eval("Password") %>'></asp:TextBox>

Or

txtPassword.Attributes.Add("Value", password);

See  AddAttributesToRender method you can find the answer. because the control is check modetype if modetype is password
that don't add the Attribute.

如何让asp.net 密码框****不会消失掉。

使用Reflector 我们可以看到它的控件会判断 Mode是不是password是的话就不把值写进来了

我们可以自己绕过这一层用txtPassword.Attributes.Add("Value", password);这样就可以把password写进来.

也可以自己弄一个小控件

以下就是PasswordBox的代码

 public class PasswordBox:TextBox,IPostBackDataHandler,ITextControl
    {
        protected override HtmlTextWriterTag TagKey
        {
            get
            {
                return HtmlTextWriterTag.Input;
            }
        }

        protected override void OnPreRender(EventArgs e)
        {
            //base.OnPreRender(e);
            this.Page.RegisterRequiresPostBack(this);

        }

        protected override void AddAttributesToRender(HtmlTextWriter writer)
        {
            writer.AddAttribute(HtmlTextWriterAttribute.Name, this.UniqueID);
            writer.AddAttribute(HtmlTextWriterAttribute.Value, this.Text);
            writer.AddAttribute(HtmlTextWriterAttribute.Type, "password");
            if (this.ID != null)
            {
                writer.AddAttribute(HtmlTextWriterAttribute.Id, this.ClientID);
            }
          
            if (!this.Enabled)
            {
                writer.AddAttribute(HtmlTextWriterAttribute.Disabled, "disabled");
            }
         
            int tabIndex = this.TabIndex;
            if (tabIndex != 0)
            {
                writer.AddAttribute(HtmlTextWriterAttribute.Tabindex, tabIndex.ToString(NumberFormatInfo.InvariantInfo));
            }
            if (!string.IsNullOrEmpty(this.CssClass))
            {
                writer.AddAttribute(HtmlTextWriterAttribute.Class, this.CssClass, false);
            }
            if (this.ControlStyleCreated && !this.ControlStyle.IsEmpty)
            {
                this.ControlStyle.AddAttributesToRender(writer, this);
            }
        }



        #region IPostBackDataHandler Members

        public new bool LoadPostData(string postDataKey, System.Collections.Specialized.NameValueCollection postCollection)
        {
            string text = this.Text;
            string str2 = postCollection[postDataKey];
            if (!text.Equals(str2, StringComparison.Ordinal))
            {
                this.Text = str2;
                return true;
            }
            return false;

        }

      
        #endregion
    }

原文地址:http://www.cnblogs.com/lovebanyi/archive/2008/10/29/1322151.html