public class CSVFileHelper
{
    /// <summary>
    /// 將DataTable中資料寫入到CSV檔案中
    /// </summary>
    /// <param name="dt">提供儲存資料的DataTable</param>
    /// <param name="fileName">CSV的檔案路徑</param>
    public static void SaveCSV(DataTable dt, string fullPath)
    {
        FileInfo fi = new FileInfo(fullPath);
        if (!fi.Directory.Exists)
        {
            fi.Directory.Create();
        }
        FileStream fs = new FileStream(fullPath, System.IO.FileMode.Create, System.IO.FileAccess.Write);
        //StreamWriter sw = new StreamWriter(fs, System.Text.Encoding.Default);
        StreamWriter sw = new StreamWriter(fs, System.Text.Encoding.UTF8);
        string data = "";
        //寫出列名稱
        for (int i = 0; i < dt.Columns.Count; i++)
        {
            data += dt.Columns[i].ColumnName.ToString();
            if (i < dt.Columns.Count - 1)
            {
                data += ",";
            }
        }
        sw.WriteLine(data);
        //寫出各行資料
        for (int i = 0; i < dt.Rows.Count; i++)
        {
            data = "";
            for (int j = 0; j < dt.Columns.Count; j++)
            {
                string str = dt.Rows[i][j].ToString();
                str = str.Replace("\"", "\"\"");//替換英文冒號 英文冒號需要換成兩個冒號
                if (str.Contains(',') || str.Contains('"') 
                    || str.Contains('\r') || str.Contains('\n')) //含逗號 冒號 換行符的需要放到引號中
                {
                    str = string.Format("\"{0}\"", str);
                }


                data += str;
                if (j < dt.Columns.Count - 1)
                {
                    data += ",";
                }
            }
            sw.WriteLine(data);
        }
        sw.Close();
        fs.Close();
        DialogResult result = MessageBox.Show("CSV檔案儲存成功！");
        if (result == DialogResult.OK)
        {
            System.Diagnostics.Process.Start("explorer.exe", Common.PATH_LANG);
        }
    }


    /// <summary>
    /// 將CSV檔案的資料讀取到DataTable中
    /// </summary>
    /// <param name="fileName">CSV檔案路徑</param>
    /// <returns>返回讀取了CSV資料的DataTable</returns>
    public static DataTable OpenCSV(string filePath)
    {
        Encoding encoding = Common.GetType(filePath); //Encoding.ASCII;//
        DataTable dt = new DataTable();
        FileStream fs = new FileStream(filePath, System.IO.FileMode.Open, System.IO.FileAccess.Read);
        
        //StreamReader sr = new StreamReader(fs, Encoding.UTF8);
        StreamReader sr = new StreamReader(fs, encoding);
        //string fileContent = sr.ReadToEnd();
        //encoding = sr.CurrentEncoding;
        //記錄每次讀取的一行記錄
        string strLine = "";
        //記錄每行記錄中的各欄位內容
        string[] aryLine = null;
        string[] tableHead = null;
        //標示列數
        int columnCount = 0;
        //標示是否是讀取的第一行
        bool IsFirst = true;
        //逐行讀取CSV中的資料
        while ((strLine = sr.ReadLine()) != null)
        {
            //strLine = Common.ConvertStringUTF8(strLine, encoding);
            //strLine = Common.ConvertStringUTF8(strLine);


            if (IsFirst == true)
            {
                tableHead = strLine.Split(',');
                IsFirst = false;
                columnCount = tableHead.Length;
                //建立列
                for (int i = 0; i < columnCount; i++)
                {
                    DataColumn dc = new DataColumn(tableHead[i]);
                    dt.Columns.Add(dc);
                }
            }
            else
            {
                aryLine = strLine.Split(',');
                DataRow dr = dt.NewRow();
                for (int j = 0; j < columnCount; j++)
                {
                    dr[j] = aryLine[j];
                }
                dt.Rows.Add(dr);
            }
        }
        if (aryLine != null && aryLine.Length > 0)
        {
            dt.DefaultView.Sort = tableHead[0] + " " + "asc";
        }
        
        sr.Close();
        fs.Close();
        return dt;
    }
}