使用导出datagrid到excel,使用下面语句:

public void savetoexcel_Click(object sender, System.EventArgs e)
{
  DataGridBind();   //捆绑数据库
  Response.Clear(); 
  Response.Buffer= true; 
  Response.Charset="gb2312";
  string Date=DateTime.Now.ToString("yyyy-MM-dd");
  string filename="单位填报表"+Date;
  Response.AddHeader("Content-Disposition","attachment;filename="+HttpUtility.UrlEncode(filename)+".xls");
  Response.ContentEncoding=System.Text.Encoding.GetEncoding("utf-8");
  Response.ContentType = "application/vnd.ms-excel";
  this.EnableViewState = false;
  System.IO.StringWriter oStringWriter = new System.IO.StringWriter(); 
  System.Web.UI.HtmlTextWriter oHtmlTextWriter = new System.Web.UI.HtmlTextWriter(oStringWriter);
  DataGrid1.RenderControl(oHtmlTextWriter);
  Response.Write(oStringWriter.ToString());
  Response.End();
  }
为什么转换的只是DataGrid1的当前页,而不是所有页???
如果能够实现所有页的转换,怎么修改呢??谢谢了!!!!