转载：GridView 空记录时显示 Header

public class GridViewEx : GridView
{

// 用于保存 Columns 中列
private ArrayList _columns;

[DefaultValue(true)]
public bool ForceShowHeader
{
get
{
object o = ViewState["ForceShowHeader"];
if (o != null)
return (bool)o;

return true;
}
set
{
ViewState["ForceShowHeader"] = value;
}
}

protected override ICollection CreateColumns(PagedDataSource dataSource, bool useDataSource)
{
if (_columns != null)
return _columns;

_columns = (ArrayList)base.CreateColumns(dataSource, useDataSource);
return _columns;
}

protected override int CreateChildControls(IEnumerable dataSource, bool dataBinding)
{
int count = base.CreateChildControls(dataSource, dataBinding);

if (ForceShowHeader && count == 0)
{
Table table;
if (Controls.Count == 0)
{
table = CreateChildTable();
Controls.Add(table);
}
else
{
table = Controls[0] as Table;
if (table == null)
throw new ApplicationException("第一个子控件不为 Table 控件");
}

DataControlField[] fields = new DataControlField[_columns.Count];
_columns.CopyTo(fields, 0);

// 创建表示头并初始化此行
GridViewRow headerRow = CreateRow(-1, -1, DataControlRowType.Header, DataControlRowState.Normal);
InitializeRow(headerRow, fields);

// 引发 RowCreated 事件
GridViewRowEventArgs args = new GridViewRowEventArgs(headerRow);
OnRowCreated(args);

// 把表头行添加到表格中
table.Rows.AddAt(0, headerRow);
}

return count;
}
}