常见hash算法.docVIP

/*** 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; ikey.length(); ++i)???? hash = (hash4)^(hash28)^key.charAt(i);?? return (hash % prime);//?? return (hash ^ (hash10) ^ (hash20));}// 替代：// 使用：hash = (hash ^ (hash10) ^ (hash20)) 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; ikey.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;}/*** Bernsteins 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; ikey.length(); ++i) hash = 33*hash + key.charAt(i);?? return hash;}////// Pearsons Hash// char pearson(char[]key, ub4 len, char tab[256])// {//?? char hash;//?? ub4 i;//?? for (hash=len, i=0; ilen; ++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; ilen; ++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 = k