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)
            {
                if (columnName=="")
                {
                    //说明txt包含列名时，不传入列名，用过读取获得列名,一般用tab分隔
                    strLine = sr.ReadLine();
                    aryLine = strLine.Split('\t');//tab分隔符
                }
                else
                {
                    strLine = columnName;
                    aryLine = strLine.Split(',');//传入列名用逗号分隔
                }
                           
                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;
        }