实现了IPostBackEventHandler接口的TextBox

    using System;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.ComponentModel;

namespace PEONormalControl
...{
    /**//// <summary>
    /// 回传事件参数类型
    /// </summary>   
    public class EventTextBoxEventArgs:EventArgs
    ...{
        private string _ToAppend;
        EventTextBoxEventArgs()
        ...{           
           
        }       
        public EventTextBoxEventArgs(String ArgText)
        ...{
            this._ToAppend=ArgText;           
        }
        /**//// <summary>
        /// 回传事件参数
        /// </summary>
        public String ArgText
        ...{
            get...{return _ToAppend;}
            set...{_ToAppend =value;}
        }
    }
    /**//// <summary>
    /// 从TextBox继承，实现了IPostBackEventHandler接口
    /// </summary>
    [DefaultProperty("Text"),
    ToolboxData("<{0}:EventTextBox runat=server></{0}:EventTextBox>")]
    public class EventTextBox : System.Web.UI.WebControls.TextBox,IPostBackEventHandler
    ...{
        //private string text;
        private static readonly object objEventChangedKey;
        public delegate void EventChangedHandler(object sender,EventTextBoxEventArgs e);

        [Bindable(false),
            Category("Appearance"),
            DefaultValue("")]
        public string PrefixText
        ...{
            get
            ...{    if    (ViewState["PrefixText"] == null)
                    return "";
                else
                return ViewState["PrefixText"].ToString() ;
            }

            set
            ...{
                ViewState["PrefixText"] = value;
            }
        }       
        /**//// <summary>
        /// 引起回传的事件名称
        /// </summary>
        [Bindable(false),
            Category("Behavior"),
            DefaultValue(""),Description("引起回传的事件名称")]           
        public string EventName
        ...{
            get
            ...{    if    (ViewState["EventName"] == null)
                    return "";
                else
                return ViewState["EventName"].ToString() ;
            }

            set
            ...{
                ViewState["EventName"] = value;
            }
        }
        /**//// <summary>
        /// 回传事件参数
        /// </summary>
        [Bindable(false),
            Category("Behavior"),
            DefaultValue(""),Description("回传事件参数")]
        public string EventArgText
        ...{
            get
            ...{    if    (ViewState["EventArgText"] == null)
                    return "";
                else
                return ViewState["EventArgText"].ToString() ;
            }

            set
            ...{
                ViewState["EventArgText"] = value;
            }
        }
        /**//// <summary>
        /// 用户自定义的回传函数
        /// </summary>
        [Bindable(false),
            Category("Behavior"),
            DefaultValue(""),Description("用户自定义的回传函数，为空则使用标准的回传函数")]
        public String UserPostBackFunction
        ...{
            get
            ...{    if    (ViewState["UserPostBackFunction"] == null)
                    return "";
                else
                return ViewState["UserPostBackFunction"].ToString() ;
            }

            set
            ...{
                ViewState["UserPostBackFunction"] = value;
            }
        }
        protected virtual void OnEventChanged(EventTextBoxEventArgs e)
        ...{
            EventChangedHandler handler1 = (EventChangedHandler) base.Events[objEventChangedKey];
            if (handler1 != null)
            ...{
                handler1(this, e);       
            }
        }
        public void RemoveStateView(String strKey)
        ...{
            this.ViewState.Remove(strKey);
        }
        [Description("EventTextBox_OnEventChanged"), Category("Action")]
        public event EventChangedHandler EventChanged
        ...{
            add
            ...{
                base.Events.AddHandler(objEventChangedKey, value);
            }
            remove
            ...{
                base.Events.RemoveHandler(objEventChangedKey, value);
            }
        }       
       
        /**//// <summary>
        /// 将此控件呈现给指定的输出参数。
        /// </summary>
        /// <param name="output"> 要写出到的 HTML 编写器 </param>
        protected override void Render(HtmlTextWriter output)
        ...{
            EventChangedHandler handler1 = (EventChangedHandler) base.Events[objEventChangedKey];
            if (handler1 != null && EventName != String.Empty)
            ...{
                base.Attributes[EventName]=UserPostBackFunction==""? Page.GetPostBackClientEvent(this,EventArgText):UserPostBackFunction;
                if(PrefixText != "" && !base.Text.StartsWith(PrefixText)) base.Text = PrefixText + base.Text;
            }
            base.Render(output);
           
        }
        //增加自己想渲染的属性
        protected override void AddAttributesToRender(HtmlTextWriter writer)
        ...{
            //writer.AddAttribute(HtmlTextWriterAttribute.Title,"PEOControl");
           
            base.AddAttributesToRender (writer);
        }

   
        IPostBackEventHandler 成员#region IPostBackEventHandler 成员

        public void RaisePostBackEvent(string eventArgument)
        ...{
            // TODO:  添加RaisePostBackEvent 实现
            EventTextBoxEventArgs e = new EventTextBoxEventArgs(eventArgument);
            OnEventChanged(e);
        }

        #endregion
    }
}