代码：

public DataTable TXTToDataTable(string fileName, string columnName)
    {
      DataTable dt = new DataTable();
      FileStream fs = new FileStream(fileName, System.IO.FileMode.Open, System.IO.FileAccess.Read);
      StreamReader sr = new StreamReader(fs, System.Text.Encoding.Default);
      //记录每次读取的一行记錄
      string strLine = "";

      //記錄每行記錄中的各字段内容
      string[] aryLine;
      //标示列数      
      int columnCount = 0;
      //标示是否是读取的第一行
      bool IsFirst = true;

      if (IsFirst == true)
      {
        //strLine = "ATTENDANCE_DATE,EMP,ATTENDANCE_DEPT,EMP_TYPE,SHITF,PLANT_CODE";
        strLine = columnName;
        aryLine = strLine.Split(',');
        IsFirst = false;
        columnCount = aryLine.Length;
        //创建列
        for (int i = 0; i < columnCount; i++)
        {
          DataColumn dc = new DataColumn(aryLine[i].ToUpper());
          dt.Columns.Add(dc);
        }
      }

      //逐行读取txt中的数據
      while ((strLine = sr.ReadLine()) != null)
      {
        aryLine = strLine.Split('\t');//tab分隔符
        DataRow dr = dt.NewRow();
        for (int j = 0; j < columnCount; j++)
        {
          dr[j] = aryLine[j].ToUpper();
        }
        dt.Rows.Add(dr);
      }

      sr.Close();
      fs.Close();
      return dt;
    }