punycode和中文相互转换

资料出处：http://blog.csdn.net/jinjazz/article/details/3981795

问题来自论坛，google了一下有java的版本，随手翻译了一下，测试没有问题

java代码来自

http://www.koders.com/java/fidA5FC1F237C9D005FD1BAD91769F8CF107601BA28.aspx

感谢原作者

 

 using System;
 using System.Collections.Generic;
 using System.Text;
 using System.Runtime.InteropServices;
 namespace ConsoleApplication9
 {
     class Program
     {
         static void Main(string[] args)
         {
             string strPunycode ="xn--"+ Punycode.encode("近身剪");
             //xn--ferv28lgza
             string strChinese = Punycode.decode("ferv28lgza");
             //近身剪
         }
     }
     class Punycode
     {
         /* Punycode parameters */
         static int TMIN = 1;
         static int TMAX = 26;
         static int BASE = 36;
         static int INITIAL_N = 128;
         static int INITIAL_BIAS = 72;
         static int DAMP = 700;
         static int SKEW = 38;
         static char DELIMITER = '-';
         /**
          * Punycodes a unicode string.
          *
          * @param input Unicode string.
          * @return Punycoded string.
          */
         public static String encode(String input)
         {
             int n = INITIAL_N;
             int delta = 0;
             int bias = INITIAL_BIAS;
             StringBuilder output = new StringBuilder();
             // Copy all basic code points to the output
             int b = 0;
             for (int i = 0; i < input.Length; i++)
             {
                 char c = input[i];
                 if (isBasic(c))
                 {
                     output.Append(c);
                     b++;
                 }
             }
             // Append delimiter
             if (b > 0)
             {
                 output.Append(DELIMITER);
             }
             int h = b;
             while (h < input.Length)
             {
                 int m = int.MaxValue;
                 // Find the minimum code point >= n
                 for (int i = 0; i < input.Length; i++)
                 {
                     int c = input[i];
                     if (c >= n && c < m)
                     {
                         m = c;
                     }
                 }
                 if (m - n > (int.MaxValue - delta) / (h + 1))
                 {
                     throw new Exception("OVERFLOW");
                 }
                 delta = delta + (m - n) * (h + 1);
                 n = m;
                 for (int j = 0; j < input.Length; j++)
                 {
                     int c = input[j];
                     if (c < n)
                     {
                         delta++;
                         if (0 == delta)
                         {
                             throw new Exception("OVERFLOW");
                         }
                     }
                     if (c == n)
                     {
                         int q = delta;
                         for (int k = BASE; ; k += BASE)
                         {
                             int t;
                             if (k <= bias)
                             {
                                 t = TMIN;
                             }
                             else if (k >= bias + TMAX)
                             {
                                 t = TMAX;
                             }
                             else
                             {
                                 t = k - bias;
                             }
                             if (q < t)
                             {
                                 break;
                             }
                             output.Append((char)digit2codepoint(t + (q - t) % (BASE - t)));
                             q = (q - t) / (BASE - t);
                         }
                         output.Append((char)digit2codepoint(q));
                         bias = adapt(delta, h + 1, h == b);
                         delta = 0;
                         h++;
                     }
                 }
                 delta++;
                 n++;
             }
             return output.ToString();
         }
         /**
          * Decode a punycoded string.
          *
          * @param input Punycode string
          * @return Unicode string.
          */
         public static String decode(String input)
         {
             int n = INITIAL_N;
             int i = 0;
             int bias = INITIAL_BIAS;
             StringBuilder output = new StringBuilder();
             int d = input.LastIndexOf(DELIMITER);
             if (d > 0)
             {
                 for (int j = 0; j < d; j++)
                 {
                     char c = input[j];
                     if (!isBasic(c))
                     {
                         throw new Exception("BAD_INPUT");
                     }
                     output.Append(c);
                 }
                 d++;
             }
             else
             {
                 d = 0;
             }
             while (d < input.Length)
             {
                 int oldi = i;
                 int w = 1;
                 for (int k = BASE; ; k += BASE)
                 {
                     if (d == input.Length)
                     {
                         throw new Exception("BAD_INPUT");
                     }
                     int c = input[d++];
                     int digit = codepoint2digit(c);
                     if (digit > (int.MaxValue - i) / w)
                     {
                         throw new Exception("OVERFLOW");
                     }
                     i = i + digit * w;
                     int t;
                     if (k <= bias)
                     {
                         t = TMIN;
                     }
                     else if (k >= bias + TMAX)
                     {
                         t = TMAX;
                     }
                     else
                     {
                         t = k - bias;
                     }
                     if (digit < t)
                     {
                         break;
                     }
                     w = w * (BASE - t);
                 }
                 bias = adapt(i - oldi, output.Length + 1, oldi == 0);
                 if (i / (output.Length + 1) > int.MaxValue - n)
                 {
                     throw new Exception("OVERFLOW");
                 }
                 n = n + i / (output.Length + 1);
                 i = i % (output.Length + 1);
                 output.Insert(i, (char)n);
                 i++;
             }
             return output.ToString();
         }
         public static int adapt(int delta, int numpoints, bool first)
         {
             if (first)
             {
                 delta = delta / DAMP;
             }
             else
             {
                 delta = delta / 2;
             }
             delta = delta + (delta / numpoints);
             int k = 0;
             while (delta > ((BASE - TMIN) * TMAX) / 2)
             {
                 delta = delta / (BASE - TMIN);
                 k = k + BASE;
             }
             return k + ((BASE - TMIN + 1) * delta) / (delta + SKEW);
         }
         public static bool isBasic(char c)
         {
             return c < 0x80;
         }
         public static int digit2codepoint(int d)
         {
             if (d < 26)
             {
                 // 0..25 : 'a'..'z'
                 return d + 'a';
             }
             else if (d < 36)
             {
                 // 26..35 : '0'..'9';
                 return d - 26 + '0';
             }
             else
             {
                 throw new Exception("BAD_INPUT");
             }
         }
         public static int codepoint2digit(int c)
         {
             if (c - '0' < 10)
             {
                 // '0'..'9' : 26..35
                 return c - '0' + 26;
             }
             else if (c - 'a' < 26)
             {
                 // 'a'..'z' : 0..25
                 return c - 'a';
             }
             else
             {
                 throw new Exception("BAD_INPUT");
             }
         }
     }
 }

 

检查结果可以用以下网站工具

http://www.nicenic.com/domain/punycode.php