C# WebUI导出Excel表

DataTable dt=ds.Tables[0];
    StringWriter sw=new StringWriter();   
    string colList="";
    for(int i=0;i<dt.Columns.Count;i++)
    {
     if(dt.Columns.Count-1!=i)
      colList+=dt.Columns[i].ColumnName.ToString()+"\t";
     else
      colList+=dt.Columns[i].ColumnName.ToString();
    }
    sw.WriteLine(colList);   
    sw.Close();

    Response.AddHeader("Content-Disposition", "attachment; filename="+filename);
    Response.ContentType = "application/ms-excel";
    Response.ContentEncoding=System.Text.Encoding.GetEncoding("GB2312");
    Response.Write(sw);
    Response.End();