eml文件格式解析就这么难嘛？

private const string encodingReg = "(?<=(Content\\-Transfer\\-Encoding\\:)).*";

//c 内容

//charset,文字编码方式,utf-8/gb2312等等

//encoding,加密编码方式,包括qp和base64两种

//因为encoding获得的加密编码标志可能不同,所以用了switch.

private string TextAnalyze(string c, string charset, string encoding)

        {

            switch (encoding.ToLower())

            {

                case "quoted-printable":

                case "qp":

                case "q":

                    try { c = QDecode(Encoding.GetEncoding(charset), c); }

                    catch (Exception e) { throw new Exception("TextAnalyze(quoted-printabl)" + e.Message); }

                    break;

                case "base64":

                case "b":

                    try

                    { c = DecodeBase64(charset, encoding); }

                    catch (Exception e) { throw new Exception("TextAnalyze(DecodeBase64)" + e.Message); }

                    break;

            }

            return c;

        }

        ///   <summary>   

        ///     quoted-printable解码程序.   

        ///   </summary>   

        ///   <param   name="encoding">解码目标字符集</param>   

        ///   <param   name="data">需要解码的字符串</param>   

        ///   <returns></returns>   

        private static string QDecode(System.Text.Encoding encoding, string data)

        {

            MemoryStream strm = new MemoryStream(System.Text.Encoding.Default.GetBytes(data));

            int b = strm.ReadByte();

            MemoryStream dStrm = new MemoryStream();

            while (b > -1)

            {

                //   Hex   eg.   =E4   

                if (b == '=')

                {

                    byte[] buf = new byte[2];

                    strm.Read(buf, 0, 2);

                    if (!(buf[0] == '\r' && buf[1] == '\n'))

                    {

                        int val = int.Parse(System.Text.Encoding.Default.GetString(buf), System.Globalization.NumberStyles.HexNumber);

                        //int   val   =   int.Parse(System.Text.Encoding.Default.GetString(buf));   

                        byte[] temp = new Byte[] { (byte)val };

                        dStrm.Write(temp, 0, temp.Length);

                    }

                }

                else

                {

                    string encodedChar = encoding.GetString(new byte[] { (byte)b });

                    byte[] d = System.Text.Encoding.Default.GetBytes(encodedChar);

                    dStrm.Write(d, 0, d.Length);

                }



                b = strm.ReadByte();

            }

            return encoding.GetString(dStrm.ToArray());

        }