webcustomcontrol1.cs

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using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Text;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Collections;
using System.Collections.Specialized;

namespace WebIpostBackDataHandler
{
    [DefaultProperty("Text")]
    [ToolboxData("<{0}:WebCustomControl1 runat=server></{0}:WebCustomControl1>")]
    public class WebCustomControl1 : WebControl, IPostBackDataHandler
    {

        public String Text
        {
            get
            {
                return (String)ViewState["Text"];
            }
            set
            {
                ViewState["Text"] = value;
            }
        }
        public event EventHandler TextChanged;//定义文本框事件
        public virtual bool LoadPostData(string postDataKey, NameValueCollection postCollection)
        {//重写方法判断文本框是否有回发数据

            String presentValue = Text;
            String postedValue = postCollection[postDataKey];

            if (presentValue == null || !presentValue.Equals(postedValue))
            {
                Text = postedValue;
                return true;//返回值为True,调用此方法后,将调用RaisePostDataChangedEvent方法引发事件
            }
            //返回值为false,调用此方法后,将不会调用RaisePostDataChangedEvent方法引发事件
            return false;
        }

        public virtual void RaisePostDataChangedEvent()//重定方法引用事件
        {
            OnTextChanged(EventArgs.Empty);
        }

        protected virtual void OnTextChanged(EventArgs e)
        {
            if (TextChanged != null)
                TextChanged(this, e);
        }
        protected override void Render(HtmlTextWriter output)
        {
            output.Write("<INPUT type= text name = " + this.UniqueID
               + " value = " + this.Text + " >");
        }
    }
}