HashUtil.java

package rfx.server.util;

import java.nio.charset.Charset;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Date;
import java.util.zip.CRC32;
import java.util.zip.Checksum;

import org.apache.commons.codec.binary.Hex;

import com.google.common.hash.HashCode;
import com.google.common.hash.HashFunction;
import com.google.common.hash.Hashing;

/**
 * @author trieu
 * 
 *         Hash function util
 * 
 */
public class HashUtil {

	/**
	 * hash url to long number <br>
	 * 
	 * MurmurHash3 is the successor to MurmurHash2. <br>
	 * It comes in 3 variants - a 32-bit version that targets low latency for
	 * hash table use and two 128-bit versions for generating unique identifiers
	 * for large blocks of data, one each for x86 and x64 platforms.
	 * 
	 * @param url
	 * @return long number
	 */
	public static long hashUrl128Bit(String url) {
		HashFunction hf = Hashing.murmur3_128();
		HashCode hc = hf.newHasher().putString(url,Charset.forName("UTF-8")).hash();
		return hc.asLong();
	}
	
	public static long hashUrlCrc64(final String url){
		return CRC64.hashByAlgo2(url.getBytes());
		//return CRC64.hashByAlgo1(url.getBytes());
	}
	
	

	public static String crc32(String s) {
		try {
			CRC32 crc32 = new CRC32();
			crc32.update(s.getBytes());
			byte[] bytesOfMessage = s.getBytes("UTF-8");

			MessageDigest md = MessageDigest.getInstance("MD5");
			byte[] thedigest = md.digest(bytesOfMessage);
			return new String(Hex.encodeHex(thedigest));
		} catch (Exception e) {
			e.printStackTrace();
		}
		return "";
	}

	public static long crc32Number(String s) {
		try {
			// Convert string to bytes
			byte bytes[] = s.getBytes();

			Checksum checksum = new CRC32();

			/*
			 * To compute the CRC32 checksum for byte array, use
			 * 
			 * void update(bytes[] b, int start, int length) method of CRC32
			 * class.
			 */

			checksum.update(bytes, 0, bytes.length);

			/*
			 * Get the generated checksum using getValue method of CRC32 class.
			 */
			long lngChecksum = checksum.getValue();

			return lngChecksum;
		} catch (Exception e) {
			e.printStackTrace();
		}
		return 0;
	}

	public static String md5(String s) {
		try {
			MessageDigest md = MessageDigest.getInstance("MD5");
			md.update(s.getBytes());

			byte byteData[] = md.digest();

			// convert the byte to hex format method 1
			StringBuffer sb = new StringBuffer();
			for (int i = 0; i < byteData.length; i++) {
				sb.append(Integer.toString((byteData[i] & 0xff) + 0x100, 16)
						.substring(1));
			}

			// convert the byte to hex format method 2
			StringBuffer hexString = new StringBuffer();
			for (int i = 0; i < byteData.length; i++) {
				String hex = Integer.toHexString(0xff & byteData[i]);
				if (hex.length() == 1)
					hexString.append('0');
				hexString.append(hex);
			}
			return hexString.toString();
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		}
		return "";
	}
	
	public static String getHash(String secretCode, String userid ){
		String ehashed = String.valueOf(HashUtil.hashUrlCrc64(secretCode+userid+ DateTimeUtil.formatHourName(new Date())));
		return ehashed;
	}
}