package cn.emay.sdk.util;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 * md5特征码工具
 * 
 * @author Frank
 *
 */
public class Md5 {

	/**
	 * MD5
	 * @param bytes
	 * @return
	 */
	public static String md5(byte[] bytes) {
		if (bytes == null || bytes.length == 0)
			return null;
		String s = null;
		char hexDigits[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
		try {
			MessageDigest md = MessageDigest.getInstance("MD5");
			md.update(bytes);
			byte tmp[] = md.digest();
			char str[] = new char[16 * 2];
			int k = 0;
			for (int i = 0; i < 16; i++) {
				byte byte0 = tmp[i];
				str[k++] = hexDigits[byte0 >>> 4 & 0xf];
				str[k++] = hexDigits[byte0 & 0xf];
			}
			s = new String(str);
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		}
		return s;
	}

	/**
	 * MD5[16位]
	 * 
	 * @param bytes
	 * @return
	 */
	public static String md5For16(byte[] bytes) {
		return md5(bytes).substring(8,24);
	}
	
}