Hash算法

C# code

Hash算法有很多很多种类。 /*** Hash算法大全<br>* 推荐使用FNV1算法* @algorithm None* @author Goodzzp 2006-11-20* @lastEdit Goodzzp 2006-11-20 * @editDetail Create*/public class HashAlgorithms{/*** 加法hash* @param key 字符串* @param prime 一个质数* @return hash结果*/public static int additiveHash(String key, int prime){   int hash, i;   for (hash = key.length(), i = 0; i < key.length(); i++)    hash += key.charAt(i);   return (hash % prime);}/*** 旋转hash* @param key 输入字符串* @param prime 质数* @return hash值*/public static int rotatingHash(String key, int prime){   int hash, i;   for (hash=key.length(), i=0; i<key.length(); ++i)     hash = (hash<<4)^(hash>>28)^key.charAt(i);   return (hash % prime);//   return (hash ^ (hash>>10) ^ (hash>>20));}// 替代：// 使用：hash = (hash ^ (hash>>10) ^ (hash>>20)) & mask;// 替代：hash %= prime;/*** MASK值，随便找一个值，最好是质数*/static int M_MASK = 0x8765fed1;/*** 一次一个hash* @param key 输入字符串* @return 输出hash值*/public static int oneByOneHash(String key){   int   hash, i;   for (hash=0, i=0; i<key.length(); ++i)   {     hash += key.charAt(i);     hash += (hash << 10);     hash ^= (hash >> 6);   }   hash += (hash << 3);   hash ^= (hash >> 11);   hash += (hash << 15);//   return (hash & M_MASK);   return hash;}/*** Bernstein's hash* @param key 输入字节数组* @param level 初始hash常量* @return 结果hash*/public static int bernstein(String key){   int hash = 0;   int i;   for (i=0; i<key.length(); ++i) hash = 33*hash + key.charAt(i);   return hash;}////// Pearson's Hash// char pearson(char[]key, ub4 len, char tab[256])// {//   char hash;//   ub4 i;//   for (hash=len, i=0; i<len; ++i) //     hash=tab[hash^key[i]];//   return (hash);// }//// CRC Hashing，计算crc,具体代码见其他// ub4 crc(char *key, ub4 len, ub4 mask, ub4 tab[256])// {//   ub4 hash, i;//   for (hash=len, i=0; i<len; ++i)//     hash = (hash >> 8) ^ tab[(hash & 0xff) ^ key[i]];//   return (hash & mask);// }/*** Universal Hashing*/public static int universal(char[]key, int mask, int[] tab){   int hash = key.length, i, len = key.length;   for (i=0; i<(len<<3); i+=8)   {     char k = key[i>>3];     if ((k&0x01) == 0) hash ^= tab[i+0];     if ((k&0x02) == 0) hash ^= tab[i+1];     if ((k&0x04) == 0) hash ^= tab[i+2];     if ((k&0x08) == 0) hash ^= tab[i+3];     if ((k&0x10) == 0) hash ^= tab[i+4];     if ((k&0x20) == 0) hash ^= tab[i+5];     if ((k&0x40) == 0) hash ^= tab[i+6];     if ((k&0x80) == 0) hash ^= tab[i+7];   }   return (hash & mask);}/*** Zobrist Hashing*/ public static int zobrist( char[] key,int mask, int[][] tab){   int hash, i;   for (hash=key.length, i=0; i<key.length; ++i)     hash ^= tab[i][key[i]];   return (hash & mask);}// LOOKUP3 // 见Bob Jenkins(3).c文件// 32位FNV算法static int M_SHIFT = 0;/*** 32位的FNV算法* @param data 数组* @return int值*/    public static int FNVHash(byte[] data)    {        int hash = (int)2166136261L;        for(byte b : data)            hash = (hash * 16777619) ^ b;        if (M_SHIFT == 0)            return hash;        return (hash ^ (hash >> M_SHIFT)) & M_MASK;    }    /**     * 改进的32位FNV算法1     * @param data 数组     * @return int值     */    public static int FNVHash1(byte[] data)    {        final int p = 16777619;        int hash = (int)2166136261L;        for(byte b:data)            hash = (hash ^ b) * p;        hash += hash << 13;        hash ^= hash >> 7;        hash += hash << 3;        hash ^= hash >> 17;        hash += hash << 5;        return hash;    }    /**     * 改进的32位FNV算法1     * @param data 字符串     * @return int值     */    public static int FNVHash1(String data)    {        final int p = 16777619;        int hash = (int)2166136261L;        for(int i=0;i<data.length();i++)            hash = (hash ^ data.charAt(i)) * p;        hash += hash << 13;        hash ^= hash >> 7;        hash += hash << 3;        hash ^= hash >> 17;        hash += hash << 5;        return hash;    }    /**     * Thomas Wang的算法，整数hash     */     public static int intHash(int key)    {      key += ~(key << 15);      key ^= (key >>> 10);      key += (key << 3);      key ^= (key >>> 6);      key += ~(key << 11);      key ^= (key >>> 16);      return key;    }    /**     * RS算法hash     * @param str 字符串     */    public static int RSHash(String str)    {        int b    = 378551;        int a    = 63689;        int hash = 0;       for(int i = 0; i < str.length(); i++)       {          hash = hash * a + str.charAt(i);          a    = a * b;       }       return (hash & 0x7FFFFFFF);    }    /* End Of RS Hash Function */    /**     * JS算法     */    public static int JSHash(String str)    {       int hash = 1315423911;       for(int i = 0; i < str.length(); i++)       {          hash ^= ((hash << 5) + str.charAt(i) + (hash >> 2));       }       return (hash & 0x7FFFFFFF);    }    /* End Of JS Hash Function */    /**     * PJW算法     */    public static int PJWHash(String str)    {        int BitsInUnsignedInt = 32;        int ThreeQuarters     = (BitsInUnsignedInt * 3) / 4;        int OneEighth         = BitsInUnsignedInt / 8;        int HighBits          = 0xFFFFFFFF << (BitsInUnsignedInt - OneEighth);        int hash              = 0;        int test              = 0;       for(int i = 0; i < str.length();i++)       {          hash = (hash << OneEighth) + str.charAt(i);          if((test = hash & HighBits) != 0)          {             hash = (( hash ^ (test >> ThreeQuarters)) & (~HighBits));          }       }       return (hash & 0x7FFFFFFF);    }    /* End Of P. J. Weinberger Hash Function */    /**     * ELF算法     */    public static int ELFHash(String str)    {        int hash = 0;        int x    = 0;       for(int i = 0; i < str.length(); i++)       {          hash = (hash << 4) + str.charAt(i);          if((x = (int)(hash & 0xF0000000L)) != 0)          {             hash ^= (x >> 24);             hash &= ~x;          }       }       return (hash & 0x7FFFFFFF);    }    /* End Of ELF Hash Function */    /**     * BKDR算法     */    public static int BKDRHash(String str)    {        int seed = 131; // 31 131 1313 13131 131313 etc..        int hash = 0;       for(int i = 0; i < str.length(); i++)       {          hash = (hash * seed) + str.charAt(i);       }       return (hash & 0x7FFFFFFF);    }    /* End Of BKDR Hash Function */    /**     * SDBM算法     */    public static int SDBMHash(String str)    {        int hash = 0;       for(int i = 0; i < str.length(); i++)       {          hash = str.charAt(i) + (hash << 6) + (hash << 16) - hash;       }       return (hash & 0x7FFFFFFF);    }    /* End Of SDBM Hash Function */    /**     * DJB算法     */    public static int DJBHash(String str)    {       int hash = 5381;       for(int i = 0; i < str.length(); i++)       {          hash = ((hash << 5) + hash) + str.charAt(i);       }       return (hash & 0x7FFFFFFF);    }    /* End Of DJB Hash Function */    /**     * DEK算法     */    public static int DEKHash(String str)    {        int hash = str.length();       for(int i = 0; i < str.length(); i++)       {          hash = ((hash << 5) ^ (hash >> 27)) ^ str.charAt(i);       }       return (hash & 0x7FFFFFFF);    }    /* End Of DEK Hash Function */    /**     * AP算法     */    public static int APHash(String str)    {        int hash = 0;       for(int i = 0; i < str.length(); i++)       {          hash ^= ((i & 1) == 0) ? ( (hash << 7) ^ str.charAt(i) ^ (hash >> 3)) :                                   (~((hash << 11) ^ str.charAt(i) ^ (hash >> 5)));       }//       return (hash & 0x7FFFFFFF);       return hash;    }    /* End Of AP Hash Function */        /**     * JAVA自己带的算法     */    public static int java(String str){   int h = 0;   int off = 0;   int len = str.length();   for (int i = 0; i < len; i++)   {    h = 31 * h + str.charAt(off++);   }   return h;}        /**     * 混合hash算法，输出64位的值     */    public static long mixHash(String str)    {    long hash = str.hashCode();    hash <<= 32;    hash |= FNVHash1(str);    return hash;    }}