判断中文是否UTF8编码

        #region 判断Url参数是否UTF8编码

        public static bool IsUTF8(string url)

        {

            byte[] buf = GetUrlCodingToBytes(url);

            return IsTextUTF8(buf);

        }

        private static bool IsTextUTF8(byte[] buf)

        {

            int i;

            byte cOctets = 0; // octets to go in this UTF-8 encoded character  

            bool bAllAscii = true;

            long iLen = buf.Length;

            for (i = 0; i < iLen; i++)

            {

                if ((buf[i] & 0x80) != 0) bAllAscii = false;



                if (cOctets == 0)

                {

                    if (buf[i] >= 0x80)

                    {

                        do

                        {

                            buf[i] <<= 1;

                            cOctets++;

                        }

                        while ((buf[i] & 0x80) != 0);



                        cOctets--;

                        if (cOctets != 2)

                            return false;

                    }

                }

                else

                {

                    if ((buf[i] & 0xC0) != 0x80)

                        return false;

                    cOctets--;

                }

            }

            if (cOctets > 0)

                return false;

            if (bAllAscii)

                return false;

            return true;

        }

        private static byte[] GetUrlCodingToBytes(string url)

        {

            StringBuilder sb = new StringBuilder();



            int i = url.IndexOf('%');

            while (i >= 0)

            {

                if (url.Length < i + 3)

                {

                    break;

                }

                sb.Append(url.Substring(i, 3));

                url = url.Substring(i + 3);

                i = url.IndexOf('%');

            }



            string urlCoding = sb.ToString();

            if (string.IsNullOrEmpty(urlCoding))

                return new byte[0];



            urlCoding = urlCoding.Replace("%", string.Empty);

            int len = urlCoding.Length / 2;

            byte[] result = new byte[len];

            len *= 2;

            for (int index = 0; index < len; index++)

            {

                string s = urlCoding.Substring(index, 2);

                int b = int.Parse(s, System.Globalization.NumberStyles.HexNumber);

                result[index / 2] = (byte)b;

                index++;

            }

            return result;

        }

        #endregion 判断Url参数是否UTF8编码

UTF-8编码规则参考

http://blog.csdn.net/sandyen/archive/2006/08/23/1108168.aspx

 上面代码是网络上找的，不过存在大部分不能识别的情况，后根据对于中文，UTF8 一定编码成 3 字节，这个原则

 修改了一下，现在大部分情况下都能正确识别