HashAlgorithm.java

package com.github.zangxiaoqiang.dfc;

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public enum HashAlgorithm {

//	/**
//	 * MD5-based hash algorithm used by ketama.
//	 */
	KETAMA_HASH;

	public long hash(byte[] digest, int nTime) {
		long rv = ((long) (digest[3+nTime*4] & 0xFF) << 24)
				| ((long) (digest[2+nTime*4] & 0xFF) << 16)
				| ((long) (digest[1+nTime*4] & 0xFF) << 8)
				| (digest[0+nTime*4] & 0xFF);
		
		return rv & 0xffffffffL; /* Truncate to 32-bits */
	}

	/**
	 * Get the md5 of the given key.
	 */
	public byte[] computeMd5(String k) {
		MessageDigest md5;
		try {
			md5 = MessageDigest.getInstance("MD5");
		} catch (NoSuchAlgorithmException e) {
			throw new RuntimeException("MD5 not supported", e);
		}
		md5.reset();
		byte[] keyBytes = null;
		try {
			keyBytes = k.getBytes("UTF-8");
		} catch (UnsupportedEncodingException e) {
			throw new RuntimeException("Unknown string :" + k, e);
		}
		
		md5.update(keyBytes);
		return md5.digest();
	}
	
	
	public static void main(String[] args){
		System.out.println(HashAlgorithm.KETAMA_HASH.hash(HashAlgorithm.KETAMA_HASH.computeMd5("/a/b/b/c") , 0));
	}
}