Java常用HASH算法总结【经典实例】

 /** * Hash算法大全
 * 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 >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> 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> 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> 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> 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 > 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 > 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 > 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 > 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 > 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