问使用类扩展网格视图作为控件

EN

using System;
using System.Data;
using System.Collections;
using System.Web.UI.WebControls;

public class GridViewEx1 : GridView
{
private DataControlFieldCollection originalColumns;

public GridViewEx1()
    : base()
{
}
public void RecordColumns()
{
    originalColumns = new DataControlFieldCollection();
    foreach (DataControlField column in Columns)
        originalColumns.Add(column as DataControlField);
}

public void ResetColumns()
{
    if (originalColumns == null)
        RecordColumns();
    else
    {
        Columns.Clear();
        foreach (DataControlField column in originalColumns)
            Columns.Add(column as DataControlField);
    }
}

protected override ICollection CreateColumns(PagedDataSource dataSource, bool useDataSource)
{
    ResetColumns();
    ICollection generatedColumns = base.CreateColumns(dataSource, useDataSource);
    foreach (DataControlField column in generatedColumns)
        if (!originalColumns.Contains(column))
            Columns.Add(column as DataControlField);
    return Columns;
}
}

gv1 = new GridViewEx1(); // gv1 is the id of my gridview