Email中Quoted Printable的解码方法

public static string QPDecode(string content,string encodingOption)
        {
            content = content.Replace("=\r\n", ""); 

             char[] chars = content.ToCharArray(); 
 
             byte[] bytes = new byte[chars.Length]; 
 
             int bytesCount = 0; 
 
             for (int i = 0; i < chars.Length; i++) 
             { 
 
                 if (chars[i] == '=') 
                 { 
                     bytes[bytesCount++] = System.Convert.ToByte(int.Parse(chars[i + 1].ToString() + chars[i + 2].ToString(), System.Globalization.NumberStyles.HexNumber)); 
 
                     i += 2; 
                 } 
                 else 
                 { 
                     bytes[bytesCount++] = System.Convert.ToByte(chars[i]); 
                 } 
             } 
 
 
             return System.Text.Encoding.GetEncoding(encodingOption).GetString(bytes, 0, bytesCount);
        }