public class CSVFileHelper
{
    /// <summary>
    /// 将DataTable中数据写入到CSV文件中
    /// </summary>
    /// <param name="dt">提供保存数据的DataTable</param>
    /// <param name="fileName">CSV的文件路径</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 = "";
        //写出列名称
        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);
        //写出各行数据
        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("\"", "\"\"");//替换英文冒号 英文冒号需要换成两个冒号
                if (str.Contains(',') || str.Contains('"') 
                    || str.Contains('\r') || str.Contains('\n')) //含逗号 冒号 换行符的需要放到引号中
                {
                    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文件保存成功！");
        if (result == DialogResult.OK)
        {
            System.Diagnostics.Process.Start("explorer.exe", Common.PATH_LANG);
        }
    }

    /// <summary>
    /// 将CSV文件的数据读取到DataTable中
    /// </summary>
    /// <param name="fileName">CSV文件路径</param>
    /// <returns>返回读取了CSV数据的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;
        //记录每次读取的一行记录
        string strLine = "";
        //记录每行记录中的各字段内容
        string[] aryLine = null;
        string[] tableHead = null;
        //标示列数
        int columnCount = 0;
        //标示是否是读取的第一行
        bool IsFirst = true;
        //逐行读取CSV中的数据
        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;
                //创建列
                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;
    }
}

/// 给定文件的路径，读取文件的二进制数据，判断文件的编码类型
/// <param name="FILE_NAME">文件路径</param>
/// <returns>文件的编码类型</returns>
 
public static System.Text.Encoding GetType(string FILE_NAME)
{
    System.IO.FileStream fs = new System.IO.FileStream(FILE_NAME, System.IO.FileMode.Open,
        System.IO.FileAccess.Read);
    System.Text.Encoding r = GetType(fs);
    fs.Close();
    return r;
}
 
/// 通过给定的文件流，判断文件的编码类型
/// <param name="fs">文件流</param>
/// <returns>文件的编码类型</returns>
public static System.Text.Encoding GetType(System.IO.FileStream fs)
{
    byte[] Unicode = new byte[] { 0xFF, 0xFE, 0x41 };
    byte[] UnicodeBIG = new byte[] { 0xFE, 0xFF, 0x00 };
    byte[] UTF8 = new byte[] { 0xEF, 0xBB, 0xBF }; //带BOM
    System.Text.Encoding reVal = System.Text.Encoding.Default;
 
    System.IO.BinaryReader r = new System.IO.BinaryReader(fs, System.Text.Encoding.Default);
    int i;
    int.TryParse(fs.Length.ToString(), out i);
    byte[] ss = r.ReadBytes(i);
    if (IsUTF8Bytes(ss) || (ss[0] == 0xEF && ss[1] == 0xBB && ss[2] == 0xBF))
    {
        reVal = System.Text.Encoding.UTF8;
    }
    else if (ss[0] == 0xFE && ss[1] == 0xFF && ss[2] == 0x00)
    {
        reVal = System.Text.Encoding.BigEndianUnicode;
    }
    else if (ss[0] == 0xFF && ss[1] == 0xFE && ss[2] == 0x41)
    {
        reVal = System.Text.Encoding.Unicode;
    }
    r.Close();
    return reVal;
}
 
/// 判断是否是不带 BOM 的 UTF8 格式
/// <param name="data"></param>
/// <returns></returns>
private static bool IsUTF8Bytes(byte[] data)
{
    int charByteCounter = 1;　 //计算当前正分析的字符应还有的字节数
    byte curByte; //当前分析的字节.
    for (int i = 0; i < data.Length; i++)
    {
        curByte = data[i];
        if (charByteCounter == 1)
        {
            if (curByte >= 0x80)
            {
                //判断当前
                while (((curByte <<= 1) & 0x80) != 0)
                {
                    charByteCounter++;
                }
                //标记位首位若为非0 则至少以2个1开始 如:110XXXXX...........1111110X　
                if (charByteCounter == 1 || charByteCounter > 6)
                {
                    return false;
                }
            }
        }
        else
        {
            //若是UTF-8 此时第一位必须为1
            if ((curByte & 0xC0) != 0x80)
            {
                return false;
            }
            charByteCounter--;
        }
    }
    if (charByteCounter > 1)
    {
        throw new Exception("非预期的byte格式");
    }
    return true;
}