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Hash算法有很多很多种类。具体的可以参考之前我写的Hash算法的一些分析。本处给大家提供一个集合了很多使用的Hash算法的类，应该可以满足不少人的需要的：Java代码/*** 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; }
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/** * 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; }}
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