转载：GridView 空记录时显示 Header

http://www.star1168.com/blog/index.php/archives/158

 

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;
    }
}

在使用的时候，把 ForceShowHeader 属性设置为 true 即可（默认值是 true