我在做gridview导出excel，我是引用别人的方法，别人的都正常，我下载后的就是乱码，可穿进去的时候显示是正常的，请问应该在哪儿修改一下呢？ 

/// <summary>
  /// 导出成Excel
  /// </summary>
  /// <param name="page">要导出的页面.如:this.Page</param>
  /// <param name="tab">包含数据的DataTable</param>
  /// <param name="FileName">要保存的文件名,如test.xls</param>
  public static void Export(System.Web.UI.Page page, System.Data.DataTable tab, string FileName)
  {
  System.Web.HttpResponse httpResponse = page.Response;
  System.Web.UI.WebControls.DataGrid dataGrid = new System.Web.UI.WebControls.DataGrid();
  dataGrid.DataSource = tab.DefaultView;
  dataGrid.AllowPaging = false;
  dataGrid.HeaderStyle.BackColor = System.Drawing.Color.Transparent;
  dataGrid.HeaderStyle.HorizontalAlign = HorizontalAlign.Center;
  dataGrid.HeaderStyle.Font.Bold = true;
  dataGrid.DataBind();
  httpResponse.AppendHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(FileName, System.Text.Encoding.UTF8)); //filename="*.xls";
  httpResponse.ContentEncoding = System.Text.Encoding.GetEncoding("UTF-8") ;
  httpResponse.ContentType = "application/ms-excel";
  System.IO.StringWriter tw = new System.IO.StringWriter();
  System.Web.UI.HtmlTextWriter hw = new System.Web.UI.HtmlTextWriter(tw);
  dataGrid.RenderControl(hw);

  string filePath = page.Server.MapPath("..") + "\\" + FileName;
  System.IO.StreamWriter sw = System.IO.File.CreateText(filePath);
  sw.Write(tw.ToString());
  sw.Close();

  DownFile(httpResponse, FileName, filePath);

  httpResponse.End();
  }

private static bool DownFile(System.Web.HttpResponse Response, string fileName, string fullPath)
  {
  try
  {
  Response.ContentType = "application/octet-stream";

  Response.AppendHeader("Content-Disposition", "attachment;filename=" +
  HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8) + ";charset=GB2312");
  System.IO.FileStream fs = System.IO.File.OpenRead(fullPath);
  long fLen = fs.Length;
  int size = 102400;//每100K同时下载数据 
  byte[] readData = new byte[size];//指定缓冲区的大小 
  if (size > fLen) size = Convert.ToInt32(fLen);
  long fPos = 0;
  bool isEnd = false;
  while (!isEnd)
  {
  if ((fPos + size) > fLen)
  {
  size = Convert.ToInt32(fLen - fPos);
  readData = new byte[size];
  isEnd = true;
  }
  fs.Read(readData, 0, size);//读入一个压缩块 
  Response.BinaryWrite(readData);
  fPos += size;
  }
  fs.Close();
  System.IO.File.Delete(fullPath);
  return true;
  }
  catch
  {
  return false;
  }
  }