我們在使用GridView的時候，很多時候需要使用CheckBox列，比如批量刪除，批量審批，但是每每都需要記住繁瑣的實現方法。多麻煩呀！再次給GridView做個手術，讓它自己就能產生CheckBox豈不爽死了。以后您就有權利忘記怎么實現CheckBox列了。哈哈，作咱們這行的，就要學的慢慢退化，什么事情都記著，累也累死了。
      下面談談我這實現的思路:
      因為GridView是基于模板的，Columns也不能在后臺添加，所以排除通過添加Column來實現，而采用在GridView創建行的時候動態創建表單元格，在表頭行上添加一個全選CheckBox，數據行上添加選擇框，點擊全選，通過向頁面注冊的腳本來實現全選。
   下面就看看關鍵的代碼：
    為了增加靈活性，添加了一個屬性，控制是否顯示CheckBox列  

   //是否顯示全選
        [
      Description("顯示全選列"),
      Category("擴展"),
        DefaultValue(false)
      ]
        public virtual bool ShowCheckAll
        {
            get
            {
                object obj2 = this.ViewState["ShowCheckAll"];
                if (obj2 != null)
                {
                    return (bool)obj2;
                }
                return false;

            }
            set
            {
                bool aShowCheckAll = this.ShowCheckAll;
                if (value != aShowCheckAll)
                {
                    this.ViewState["ShowCheckAll"] = value;
                    if (base.Initialized)
                    {
                        base.RequiresDataBinding = true;
                    }
                }
            }
        }

用于控制選擇列是添加到表的左端還是右端的屬性

 public enum CheckColumnAlign
    {
        Left, Right
    }

   //是否顯示全選
        [
      Description("全選列的位置"),
      Category("擴展"),
      DefaultValue(CheckColumnAlign.Left)
      ]
        public virtual CheckColumnAlign CheckColumnAlign
        {
            get
            {
                object obj2 = this.ViewState["CheckColumnAlign"];
                if (obj2 != null)
                {
                    return (CheckColumnAlign)obj2;
                }
                return CheckColumnAlign.Left;
            }
            set
            {
                CheckColumnAlign aCheckColumnAlign = this.CheckColumnAlign;
                if (value != aCheckColumnAlign)
                {
                    this.ViewState["CheckColumnAlign"] = value;
                    if (base.Initialized)
                    {
                        base.RequiresDataBinding = true;
                    }
                }
            }
        }

在頁面加載的時候，注冊全選腳本

 StringBuilder sb = new StringBuilder();
            sb.Append(" <script type=\"text/javascript\">");
            sb.Append("function CheckAll(oCheckbox)");
            sb.Append("{");
            sb.Append("var GridView2 = document.getElementById(\"" + this.ClientID + "\");");
            sb.Append(" for(i = 1;i < GridView2.rows.length; i++)");
            sb.Append("{");
            sb.Append("var inputArray = GridView2.rows[i].getElementsByTagName(\"INPUT\");");
            sb.Append("for(var j=0;j<inputArray.length;j++)");
            sb.Append("{ if(inputArray[j].type=='checkbox')");
            sb.Append("{if(inputArray[j].id.indexOf('ItemCheckBox',0)>-1){inputArray[j].checked =oCheckbox.checked; }}  }");
            sb.Append("}");
            sb.Append(" }");
            sb.Append("</script>");
            ScriptManager.RegisterClientScriptBlock(this, this.GetType(), "CheckFun", sb.ToString(), false);

在GridView的RowCreate事件中，添加如下代碼，用于創建CheckBox列

   if (ShowCheckAll)
                {
                    GridViewRow row = e.Row;
                    if (row.RowType == DataControlRowType.Header)
                    {
                        TableCell cell = new TableCell();
                        cell.Wrap = Wrap;
                        cell.Width = Unit.Pixel(50);
                        cell.Text = " <input id='Checkbox2' type='checkbox' onclick='CheckAll(this)'/><label>全選</label>";
                        if (CheckColumnAlign == CheckColumnAlign.Left)
                        {
                            row.Cells.AddAt(0, cell);
                        }
                        else
                        {
                            int index = row.Cells.Count;
                            row.Cells.AddAt(index, cell);
                        }
                    }
                    else if (row.RowType == DataControlRowType.DataRow)
                    {
                        TableCell cell = new TableCell();
                        cell.Wrap = Wrap;
                        CheckBox cb = new CheckBox();
                        cell.Width = Unit.Pixel(50);
                        cb.ID = "ItemCheckBox";
                        cell.Controls.Add(cb);
                        if (CheckColumnAlign == CheckColumnAlign.Left)
                        {
                            row.Cells.AddAt(0, cell);
                        }
                        else
                        {
                            int index = row.Cells.Count;
                            row.Cells.AddAt(index, cell);
                        }
                    }
                }

用于記錄CheckBox的ID的屬性

 public string CheckBoxID
        {
            get
            {
                return "ItemCheckBox";
            }
        }

使用的時候，只需要設置擴展GridView的ShowCheckAll=True,設置CheckColumnAlign為Left,CheckBox列在最左邊，Right在最右面，注意因為沒有添加Columns，所以Columns并沒有因為因為添加了CheckBox列而變化，在Column的索引中，CheckBox列不在計算范圍。
在擴展的GridView的OnRowDataBound事件中，就可以通過
CheckBox cb = e.Row.FindControl(gridView.CheckBoxID) as CheckBox;
if(cb!=null)
{ 
    if(cb.Checked)
   {
        //...
   }
}
來獲取是否已經選中此行。
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