服务器控件数据回发实现IPostBackDataHandler需注意的

using System;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.ComponentModel;
using System.Linq;
using System.Resources;
using System.Text;
using System.Threading.Tasks;
using System.Web;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;

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

        public string ColorValue
        {
            get
            {
                string viewstr = this.ID + "_ColorValue";
                object text = ViewState[viewstr];
                if (text == null)
                    return string.Empty;
                else
                    return (string)text;
            }
            set
            {
                string viewstr = this.ID + "_ColorValue";
                ViewState[viewstr] = value;
            }
        }

        public string DivContranerID
        {
            get
            {
                string viewstr = this.ID + "_DivContranerID";
                String s = (String)ViewState[viewstr];
                return ((s == null) ? this.ID + "DecTextBox" : s);
            }

            set
            {
                string viewstr = this.ID + "_DivContranerID";
                ViewState[viewstr] = value;
            }
        }

        public string PickerBtnID
        {
            get
            {
                string viewstr = this.ID + "_PickerBtnID";
                String s = (String)ViewState[viewstr];
                return ((s == null) ? this.ID + "_PickerBtn" : s);
            }

            set
            {
                string viewstr = this.ID + "_PickerBtnID";
                ViewState[viewstr] = value;
            }
        }

        [Description("设置按钮的文本")]
        public string PickerBtnText
        {
            get
            {
                string viewstr = this.ID + "_PickerBtnText";
                String s = (String)ViewState[viewstr];
                return ((s == null) ? "选择颜色" : s);
            }

            set
            {
                string viewstr = this.ID + "_PickerBtnText";
                ViewState[viewstr] = value;
            }
        }

        [Description("是否显示按钮")]
        public bool ShowPickerBtn
        {
            get
            {
                string viewstr = this.ID + "_ShowPickerBtn";
                var s = ViewState[viewstr];
                return s == null ? true : (Convert.ToBoolean(s));
            }

            set
            {
                string viewstr = this.ID + "_ShowPickerBtn";
                ViewState[viewstr] = value;
            }
        }

        #region 选择器配置

        [Bindable(false), DefaultValue(""), Browsable(true), Description("颜色选择器的宽度"), Category("选择器设置")]
        public string PickerWidth
        {
            get
            {
                string viewstr = this.ID + "_PickerWidth";
                String s = (String)ViewState[viewstr];
                return ((s == null) ? "" : s);
            }
            set
            {
                string viewstr = this.ID + "_PickerWidth";
                ViewState[viewstr] = value;
            }
        }
        [Bindable(false), DefaultValue(""), Browsable(true), Description("颜色选择器的高度"), Category("选择器设置")]
        public string PickerHeight
        {
            get
            {
                string viewstr = this.ID + "_PickerHeight";
                String s = (String)ViewState[viewstr];
                return ((s == null) ? "" : s);
            }
            set
            {
                string viewstr = this.ID + "_PickerHeight";
                ViewState[viewstr] = value;
            }
        }

        #endregion

        public string Text
        {
            get
            {
                object text = ViewState["Text"];
                if (text == null)
                    return string.Empty;
                else
                    return (string)text;
            }
            set
            {
                ViewState["Text"] = value;
            }
        }
        public event EventHandler TextChanged;

        protected void OnTextChanged(EventArgs e)
        {
            if (TextChanged != null)
                TextChanged(this, e);
        }

        public bool LoadPostData(string postDataKey, NameValueCollection postCollection)
        {
            string postedData = postCollection[postDataKey];//回发回来的字符串

            if (!this.ColorValue.Equals(postedData))
            {
                this.ColorValue = postedData;
                return true;
            }
            else
            {
                return false;
            }
        }

        public void RaisePostDataChangedEvent()
        {
            OnTextChanged(EventArgs.Empty);
        }
        protected override void Render(HtmlTextWriter writer)
        {
            StringBuilder sb = new StringBuilder();
            sb.AppendFormat("<div id=\"{0}\">", this.DivContranerID);
            sb.AppendFormat("<script>{0}</script>", DecColorPicker.Properties.Resources.colorPicker);
            //注意此处必须为UniqueID 原因是与LoadPostData的postDataKey 一一对应 lcc
            sb.AppendFormat("<input type='text' onclick='colorPicker(event)' id='{0}' name='{0}' />", this.UniqueID);
            if (this.ShowPickerBtn)
            {
                sb.AppendFormat("<input type=\"button\" value=\"{0}\" onclick=\"document.getElementById('{1}').click();\">", this.PickerBtnText, this.UniqueID);

            }
            sb.Append("</div>");
            writer.Write(sb.ToString());

        }
    }
}