导出数据到Excel

  /// <summary>
  /// 导出数据到一个excel文件
  /// </summary>
  /// <returns>文件名称</returns>
  public string ExportToExcel()
  {
   //You use these variables throughout the application.
   string fileExcel;
   string fileName;
   string strLine;
   FileStream objFileStream;
   StreamWriter objStreamWriter;
   Random nRandom = new Random(DateTime.Now.Millisecond);
   //Create a random file name.
   fileExcel = "t" + nRandom.Next().ToString() + ".xls";                   
   //Set a virtual folder to save the file.
   fileName = filePath + "\\" + fileExcel;
   //Use FileSystem objects to create the .xls file.
   objFileStream = new FileStream(fileName, FileMode.OpenOrCreate, FileAccess.Write);         
   objStreamWriter = new StreamWriter(objFileStream,System.Text.Encoding.Default);
   objStreamWriter.WriteLine(fileHeader);
   //Reinitialize the string for data.
   strLine = "";
   //Enumerate the database that is used to populate the file.
   for (int j=0;j<=DataDt.Rows.Count-1;j++)
   {
    for (int i = 0; i <=DataDt.Columns.Count-1; i++)
    {
     strLine = strLine +DataDt.Rows[j][i].ToString()+Convert.ToChar(9);
    }                   
    objStreamWriter.WriteLine(strLine);
    strLine="";
   }
   //Clean up.
   objStreamWriter.Close();
   objFileStream.Close();
   return filePath + "\\" + fileExcel;
  //return fileExcel;
  }