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; 
  } 
}