GridView自定义分页

protected void Page_Load(object sender, EventArgs e)
    {
        btnFirst.Text = "最首页";
        btnPrev.Text = "前一页";
        btnNext.Text = "下一页";
        btnLast.Text = "最后页";
        GridView1.DataBind();
        ShowPageChangedStatus();

    }
   private void ShowPageChangedStatus()
  {
        lblCurrentIndex.Text = "第" + (GridView1.PageIndex + 1).ToString() + "页";
        lblPageCount.Text = "总共 " + GridView1.PageCount.ToString() + " 页";
    }
    public void PagerButtonClick(object sender, EventArgs e)
    {
        string arg = ((LinkButton)sender).CommandArgument.ToString();
        switch (arg)
        {
            case "next":
                if (GridView1.PageIndex < (GridView1.PageCount - 1))
                {
                    GridView1.PageIndex += 1;
                }
                break;
            case "prev":
                if (GridView1.PageIndex > 0)
                {
                    GridView1.PageIndex -= 1;
                }
                break;
            case "last":
                GridView1.PageIndex = (GridView1.PageCount - 1);
                break;
            default:
                GridView1.PageIndex = System.Convert.ToInt32(arg);
                break;
        }
        GridView1.DataBind();
        ShowPageChangedStatus();
    }
    protected void GridView1_PageIndexChanging(object sender, GridViewPageEventArgs e)
    {
        int startIndex;
        startIndex = GridView1.PageIndex * GridView1.PageSize;
        GridView1.PageIndex = e.NewPageIndex;
        GridView1.DataBind();
        ShowPageChangedStatus();

    }