public class IPScanner
{
        //私有成员#region 私有成员
        private string dataPath;
        private string ip;
        private string country;
        private string local;

        private long firstStartIp = 0;
        private long lastStartIp = 0;
        private FileStream objfs = null;
        private long startIp = 0;
        private long endIp = 0;
        private int countryFlag = 0;
        private long endIpOff = 0;
        private string errMsg = null;

        //构造函数#region 构造函数
        public IPScanner()
        {
            this.dataPath = System.Web.HttpContext.Current.Server.MapPath("/ipdata/QQWry.dat");
        }

        //公共属性#region 公共属性
        public string DataPath
        {
            set { dataPath = value; }
        }
        public string IP
        {
            set { ip = value; }
        }
        public string Country
        {
            get { return country; }
        }
        public string Local
        {
            get { return local; }
        }
        public string ErrMsg
        {
            get { return errMsg; }
        }

        //搜索匹配数据#region 搜索匹配数据
        private int QQwry()
        {
            string pattern = @"(((\\d{1,2})|(1\\d{2})|(2[0-4]\\d)|(25[0-5]))\\.){3}((\\d{1,2})|(1\\d{2})|(2[0-4]\\d)|(25[0-5]))";
            Regex objRe = new Regex(pattern);
            Match objMa = objRe.Match(ip);
            if (!objMa.Success)
            {
                this.errMsg = "IP格式错误";
                return 4;
            }

            long ip_Int = this.IpToInt(ip);
            int nRet = 0;
            if (ip_Int >= IpToInt("127.0.0.0") ip_Int = IpToInt("127.255.255.255"))
            {
                this.country = "本机内部环回地址";
                this.local = "";
                nRet = 1;
            }
            else if ((ip_Int >= IpToInt("0.0.0.0") ip_Int = IpToInt("2.255.255.255")) || (ip_Int >= IpToInt("64.0.0.0") ip_Int = IpToInt("126.255.255.255")) || (ip_Int >= IpToInt("58.0.0.0") ip_Int = IpToInt("60.255.255.255")))
            {
                this.country = "网络保留地址";
                this.local = "";
                nRet = 1;
            }
            objfs = new FileStream(this.dataPath, FileMode.Open, FileAccess.Read);
            try
            {
                objfs.Position = 0;
                byte[] buff = new Byte[8];
                objfs.Read(buff, 0, 8);
                firstStartIp = buff[0] + buff[1] * 256 + buff[2] * 256 * 256 + buff[3] * 256 * 256 * 256;
                lastStartIp = buff[4] * 1 + buff[5] * 256 + buff[6] * 256 * 256 + buff[7] * 256 * 256 * 256;
                long recordCount = Convert.ToInt64((lastStartIp - firstStartIp) / 7.0);
                if (recordCount = 1)
                {
                    country = "FileDataError";
                    objfs.Close();
                    return 2;
                }
                long rangE = recordCount;
                long rangB = 0;
                long recNO = 0;
                while (rangB rangE - 1)
                {
                    recNO = (rangE + rangB) /2;
                    this.GetStartIp(recNO);
                    if (ip_Int ==this.startIp)
                    {
                        rangB = recNO;
                        break;
                    }if (ip_Int >this.startIp)
                        rangB = recNO;
                    else
                        rangE = recNO;
                }this.GetStartIp(rangB);
                this.GetEndIp();
                if (this.startIp = ip_Int this.endIp >= ip_Int)
                {
                    this.GetCountry();
                    this.local =this.local.Replace("（我们一定要解放台湾！！！）", "");
                }else{
                    nRet =3;
                    this.country ="未知";
                    this.local ="";
                }
                objfs.Close();
                return nRet;
            }catch{
                return1;
            }
        }// IP地址转换成Int数据#region IP地址转换成Int数据 privatelong IpToInt(string ip)
        {
            char[] dot =newchar[] { '.' };
            string[] ipArr = ip.Split(dot);
            if (ipArr.Length ==3)
                ip = ip +".0";
            ipArr = ip.Split(dot);

            long ip_Int =0;
            long p1 =long.Parse(ipArr[0]) *256*256*256;
            long p2 =long.Parse(ipArr[1]) *256*256;
            long p3 =long.Parse(ipArr[2]) *256;
            long p4 =long.Parse(ipArr[3]);
            ip_Int = p1 + p2 + p3 + p4;
            return ip_Int;
        }//获取起始IP范围#region 获取起始IP范围 privatelong GetStartIp(long recNO)
        {
            long offSet = firstStartIp + recNO *7;
            //objfs.Seek(offSet,SeekOrigin.Begin);             objfs.Position = offSet;
            byte[] buff =new Byte[7];
            objfs.Read(buff, 0, 7);

            endIpOff = Convert.ToInt64(buff[4].ToString()) + Convert.ToInt64(buff[5].ToString()) *256+ Convert.ToInt64(buff[6].ToString()) *256*256;
            startIp = Convert.ToInt64(buff[0].ToString()) + Convert.ToInt64(buff[1].ToString()) *256+ Convert.ToInt64(buff[2].ToString()) *256*256+ Convert.ToInt64(buff[3].ToString()) *256*256*256;
            return startIp;
        }// 获取结束IP#region 获取结束IP privatelong GetEndIp()
        {
            //objfs.Seek(endIpOff,SeekOrigin.Begin);             objfs.Position = endIpOff;
            byte[] buff =new Byte[5];
            objfs.Read(buff, 0, 5);
            this.endIp = Convert.ToInt64(buff[0].ToString()) + Convert.ToInt64(buff[1].ToString()) *256+ Convert.ToInt64(buff[2].ToString()) *256*256+ Convert.ToInt64(buff[3].ToString()) *256*256*256;
            this.countryFlag = buff[4];
            returnthis.endIp;
        }//获取国家/区域偏移量#region 获取国家/区域偏移量 privatestring GetCountry()
        {
            switch (this.countryFlag)
            {
                case1:
                case2:
                    this.country = GetFlagStr(this.endIpOff +4);
                    this.local = (1==this.countryFlag) ?"" : this.GetFlagStr(this.endIpOff +8);
                    break;
                default:
                    this.country =this.GetFlagStr(this.endIpOff +4);
                    this.local =this.GetFlagStr(objfs.Position);
                    break;
            }return"";
        }//获取国家/区域字符串#region 获取国家/区域字符串 privatestring GetFlagStr(long offSet)
        {
            int flag =0;
            byte[] buff =new Byte[3];
            while (1==1)
            {
                objfs.Position = offSet;
                flag = objfs.ReadByte();
                if (flag ==1|| flag ==2)
                {
                    objfs.Read(buff, 0, 3);
                    if (flag ==2)
                    {
                        this.countryFlag =2;
                        this.endIpOff = offSet -4;
                    }
                    offSet = Convert.ToInt64(buff[0].ToString()) + Convert.ToInt64(buff[1].ToString()) *256+ Convert.ToInt64(buff[2].ToString()) *256*256;
                }else{
                    break;
                }
            }if (offSet 12)
                return"";
            objfs.Position = offSet;
            return GetStr();
        }//GetStr#region GetStr privatestring GetStr()
        {
            byte lowC =0;
            byte upC =0;
            string str ="";
            byte[] buff =newbyte[2];
            while (1==1)
            {
                lowC = (Byte)objfs.ReadByte();
                if (lowC ==0)
                    break;
                if (lowC >127)
                {
                    upC = (byte)objfs.ReadByte();
                    buff[0] = lowC;
                    buff[1] = upC;
                    System.Text.Encoding enc = System.Text.Encoding.GetEncoding("GB2312");
                    str += enc.GetString(buff);
                }else{
                    str += (char)lowC;
                }
            }return str;
        }publicstring IPLocation(string ip)
        {
            this.ip = ip;
            this.QQwry();
            if (this.country.Trim().Contains(this.local.Trim()))
                returnthis.country.Trim();
            returnthis.country.Trim() +this.local.Trim();
        }
}

string ip="123.81.176.99";
IPScanner ipscaner = new IPScanner();
ipscaner.IPLocation(ip); 
string strIPAddress=ipscaner.Country;