扩展GridView，增加单选按钮列

刚写的热乎乎的代码：

/// <summary>
    /// 单选按钮列
    /// </summary>
    /// <remarks>
    /// 如果没有设置GroupName，则使用GridView的ID作为GroupName
    /// 如果没有设置DataField，则使用RowIndex作为Value
    /// 允许设置DataFormatString格式化数据
    /// </remarks>
    [AspNetHostingPermission(SecurityAction.Demand,
      Level = AspNetHostingPermissionLevel.Minimal)]
    public class RadioButtonSelectField : DataControlField
    {
        /// <summary>
        /// 单选按钮组名，默认去GridView的ClientID
        /// </summary>
        [Description("单选按钮组名，默认去GridView的ClientID")]
        public string RadioButtonGroupName
        {
            get
            {
                return this.ViewState["RadioButtonGroupName"] as string;
            }
            set
            {
                this.ViewState["RadioButtonGroupName"] = value;
            }
        }

        /// <summary>
        /// 单选按钮的样式
        /// </summary>
        [Description("单选按钮的样式")]
        public string RadioButtonCssClass
        {
            get
            {
                return this.ViewState["RadioButtonCssClass"] as string;
            }
            set
            {
                this.ViewState["RadioButtonCssClass"] = value;
            }
        }

        /// <summary>
        /// 要绑定的数据表达式
        /// </summary>
        [Description("要绑定的数据表达式")]
        public string DataField
        {
            get
            {
                return this.ViewState["DataField"] as string;
            }
            set
            {
                this.ViewState["DataField"] = value;
            }
        }

        /// <summary>
        /// 要绑定的数据表达式格式
        /// </summary>
        [Description("要绑定的数据表达式格式")]
        public string DataFormatString
        {
            get
            {
                return this.ViewState["DataFormatString"] as string;
            }
            set
            {
                this.ViewState["DataFormatString"] = value;
            }
        }

        /// <summary>
        /// return self;
        /// </summary>
        /// <returns></returns>
        protected override DataControlField CreateField()
        {
            return this;
        }

        /// <summary>
        /// 添加控件
        /// </summary>
        /// <param name="cell"></param>
        /// <param name="cellType"></param>
        /// <param name="rowState"></param>
        /// <param name="rowIndex"></param>
        public override void InitializeCell(DataControlFieldCell cell, DataControlCellType cellType, DataControlRowState rowState, int rowIndex)
        {
            base.InitializeCell(cell, cellType, rowState, rowIndex);

            if (cellType == DataControlCellType.DataCell)
            {
                var literal = new Literal();

                if (string.IsNullOrEmpty(this.DataField))
                {
                    SetLiteralHtml(literal, rowIndex.ToString());
                }
                else
                {
                    literal.DataBinding += new EventHandler(literal_DataBinding);
                }
                
                cell.Controls.Add(literal);
            }
        }

        void literal_DataBinding(object sender, EventArgs e)
        {
            if (string.IsNullOrEmpty(this.DataField))
            {
                return;
            }

            var literal = sender as Literal;
            if (literal == null)
            {
                return;
            }
            var cell = literal.Parent as TableCell;
            if (cell == null)
            {
                return;
            }
            var container = literal.NamingContainer;
            if (container == null)
            {
                return;
            }
            bool foundDataItem;
            var dataItem = DataBinder.GetDataItem(container, out foundDataItem);
            if (!foundDataItem)
            {
                return;
            }

            var dataValue = null as string;
            if (this.DataField.Contains('.'))
            {
                dataValue = DataBinder.Eval(dataItem, this.DataField, this.DataFormatString);
            }
            else
            {
                dataValue = DataBinder.GetPropertyValue(dataItem, this.DataField, this.DataFormatString);
            }

            SetLiteralHtml(literal, dataValue);
        }

        private void SetLiteralHtml(Literal literal, string dataValue)
        {
            var groupName = this.RadioButtonGroupName;
            if (string.IsNullOrEmpty(groupName))
            {
                groupName = literal.Parent.Parent.Parent.Parent.ID;
            }
            var cssClass = this.RadioButtonCssClass;
            if (!string.IsNullOrEmpty(cssClass))
            {
                cssClass = string.Format("class=\"{0}\"", this.RadioButtonCssClass);
            }

            var selected = false;
            var selectedValue = literal.Page.Request[groupName];
            if (string.IsNullOrEmpty(selectedValue) == false)
            {
                if (string.Compare(selectedValue, dataValue, true) == 0)
                {
                    selected = true;
                }
            }

            var rbHtml = string.Format("<input type=\"radio\" name=\"{0}\" value=\"{1}\" {2} {3} />",
                groupName,
                dataValue,
                cssClass,
                selected ? "checked" : string.Empty);

            literal.Text = rbHtml;
        }
    }