各种哈希函数的java实现

//收集整理

public class HashUtils {
	private static final int crctab[] = { 0x00000000, 0x77073096, 0xee0e612c, 0x990951ba,
			0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e,
			0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2,
			0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, 0x136c9856,
			0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5,
			0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd,
			0xa50ab56b, 0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75,
			0xdcd60dcf, 0xabd13d59, 0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5,
			0x56b3c423, 0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
			0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, 0x01db7106, 0x98d220bc,
			0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433, 0x7807c9a2, 0x0f00f934,
			0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01, 0x6b6b51f4,
			0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457,
			0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3,
			0xfbd44c65, 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7,
			0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73,
			0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086,
			0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f, 0x5edef90e, 0x29d9c998, 0xb0d09822,
			0xc7d7a8b4, 0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6,
			0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12,
			0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
			0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb, 0x196c3671,
			0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9,
			0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1,
			0xa6bc5767, 0x3fb506dd, 0x48b2364b, 0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60,
			0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0,
			0x5268e236, 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28,
			0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d, 0x9b64c2b0,
			0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
			0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7,
			0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b,
			0x6fb077e1, 0x18b74777, 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff,
			0xf862ae69, 0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
			0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 0x40df0b66,
			0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9, 0xbdbdf21c, 0xcabac28a,
			0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf, 0xb3667a2e,
			0xc4614ab8, 0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d };

	public static int crc32Hash(String key) {
		int n = key.length();
		int hash = n;
		for (int i = 0; i < n; ++i)
			hash = (hash >> 8) ^ crctab[(hash & 0xff) ^ key.charAt(i)];
		return hash;
	}

	public static int additiveHash(String key) {
		int n = key.length();
		int hash = n;
		for (int i = 0; i < n; i++)
			hash += key.charAt(i);
		return hash ^ (hash >> 10) ^ (hash >> 20);
	}

	public static int rotatingHash(String key) {
		int n = key.length();
		int hash = n;
		for (int i = 0; i < n; i++)
			hash = (hash << 4) ^ (hash >> 28) ^ key.charAt(i);
		return (hash & 0x7FFFFFFF);
	}

	/**
	 * @param key
	 * @param prime
	 *            31 131 1313 13131 131313 etc..
	 * @return
	 */
	public static int BKDRHash(String key, int prime) {
		int hash = 0;
		int n = key.length();
		for (int i = 0; i < n; ++i)
			hash = prime * hash + key.charAt(i);
		return (hash & 0x7FFFFFFF);
	}

	public static int FNVHash(String key) {
		final int p = 16777619;
		int hash = (int) 2166136261L;
		int n = key.length();
		for (int i = 0; i < n; i++)
			hash = (hash ^ key.charAt(i)) * p;
		hash += hash << 13;
		hash ^= hash >> 7;
		hash += hash << 3;
		hash ^= hash >> 17;
		hash += hash << 5;
		return (hash & 0x7FFFFFFF);
	}

	public static int RSHash(String key) {
		int b = 378551;
		int a = 63689;
		int hash = 0;
		int n = key.length();
		for (int i = 0; i < n; i++) {
			hash = hash * a + key.charAt(i);
			a = a * b;
		}
		return (hash & 0x7FFFFFFF);
	}

	public static int JSHash(String key) {
		int hash = 1315423911;
		int n = key.length();
		for (int i = 0; i < n; i++) {
			hash ^= ((hash << 5) + key.charAt(i) + (hash >> 2));
		}
		return (hash & 0x7FFFFFFF);
	}

	// P. J. Weinberger Hash Function
	public static int PJWHash(String key) {
		int BitsInUnignedInt = 32;
		int ThreeQuarters = 24;
		int OneEighth = 4;
		int HighBits = (0xFFFFFFFF) << (BitsInUnignedInt - OneEighth);
		int hash = 0;
		int test = 0;
		int n = key.length();
		for (int i = 0; i < n; i++) {
			hash = (hash << OneEighth) + key.charAt(i);
			if ((test = hash & HighBits) != 0) {
				hash = ((hash ^ (test >> ThreeQuarters)) & (~HighBits));
			}
		}
		return (hash & 0x7FFFFFFF);
	}

	public static int ELFhash(String key) {
		int h = 0;
		int n = key.length();
		for (int i = 0; i < n; i++) {
			h = (h << 4) + key.charAt(i);
			long g = h & 0Xf0000000L;
			if (g != 0) {
				h ^= g >> 24;
				h &= ~g;
			}
		}
		return (h & 0x7FFFFFFF);
	}

	// SDBM Hash Function
	public static int SDBMHash(String key) {
		int hash = 0;
		int n = key.length();
		for (int i = 0; i < n; i++) {
			hash = key.charAt(i) + (hash << 6) + (hash << 16) - hash;
		}
		return (hash & 0x7FFFFFFF);
	}

	// DJB Hash Function
	public static int DJBHash(String key) {
		int hash = 5381;
		int n = key.length();
		for (int i = 0; i < n; i++) {
			hash += (hash << 5) + key.charAt(i);
		}
		return (hash & 0x7FFFFFFF);
	}

	// AP Hash Function
	public static int APHash(String key) {
		int hash = 0;
		int n = key.length();
		for (int i = 0; i < n; i++) {
			if ((i & 1) == 0) {
				hash ^= ((hash << 7) ^ key.charAt(i) ^ (hash >> 3));
			} else {
				hash ^= (~((hash << 11) ^ key.charAt(i) ^ (hash >> 5)));
			}
		}
		return (hash & 0x7FFFFFFF);
	}
}