public class Md5Util {

     private String Md5Util(String s) {

         try {

             MessageDigest md = MessageDigest.getInstance("MD5");

             byte[] bytes = md.digest(s.getBytes("utf-8"));

             return toHex(bytes);

         } catch (Exception e) {

             throw new RuntimeException(e);

         }

     }

     private static String toHex(byte[] bytes) {

         final char[] HEX_DIGITS = "0123456789abcdef".toCharArray();

         StringBuilder ret = new StringBuilder(bytes.length * 2);

         for (int i = 0; i < bytes.length; i++) {

             ret.append(HEX_DIGITS[(bytes[i] >> 4) & 0x0f]);

             ret.append(HEX_DIGITS[bytes[i] & 0x0f]);

         }

         return ret.toString();

     }

 }