hash

 

HashSet Set接口，元素不能重复，要确保重写hashCode（）方法和equals（）方法，这样才能比较对象的值是否相等

HashMap Map接口，key可为null
线程安全ConcurrentHashMap（Map接口）、HashTable
按次序存储LinkedHashMap（HashMap，Map接口）
排序TreeMap Map接口

 

 

package com.xmh.mq;
/** 
* 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 HashAll 
{ /**//** * 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; } 
}