求怎么获取GridView里面的数据。。然后把数据导出为Excel或txt文档的ASP.NET源码

简单代码:

Response.ClearContent();
Response.AddHeader("content-disposition", "attachment; filename=ExportFile.xls");
Response.ContentType = "application/excel";
StringWriter sw = new StringWriter();
HtmlTextWriter htw = new HtmlTextWriter(sw);
GridView1.RenderControl(htw);
Response.Write(sw.ToString());
Response.End();