这篇文章主要介绍了Java常用HASH算法,结合实例形式总结分析了Java常用的Hash算法,包括加法hash、旋转hash、FNV算法、RS算法hash、PJW算法、ELF算法、BKDR算法、SDBM算法、DJB算法、DEK算法、AP算法等,需要的朋友可以参考下
本文实例讲述了Java常用HASH算法。分享给大家供大家参考，具体如下：
/*** 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; }}
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