手把手教你如何扩展GridView之自带CheckBox

在页面加载的时候，注册全选脚本

 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，添加如下代码，用于创建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>全选</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);
                        }
                    }
                }

用于记录CheckBox的ID的属性

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

使用的时候，只需要设置扩展GridView的ShowCheckAll=True,设置CheckColumnAlign为Left,CheckBox列在最左边，Right在最右面，注意因为没有添加Columns，所以Columns并没有因为因为添加了CheckBox列而变化，在Column的索引中，CheckBox列不在计算范围。
在扩展的GridView的OnRowDataBound事件中，就可以通过
CheckBox cb = e.Row.FindControl(gridView.CheckBoxID) as CheckBox;
if(cb!=null)
{ 
    if(cb.Checked)
   {
        //...
   }
}
来获取是否已经选中此行。
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