/**

      * 将字符串转成MD5值

      *

      * @param string

      * @return

      */

     public static String stringToMD5(String string) {

         byte[] hash;  

         try {

             hash = MessageDigest.getInstance("MD5").digest(string.getBytes("UTF-8"));

         } catch (NoSuchAlgorithmException e) {

             e.printStackTrace();

             return null;

         } catch (UnsupportedEncodingException e) {

             e.printStackTrace();

             return null;

         }  

         StringBuilder hex = new StringBuilder(hash.length * 2);

         for (byte b : hash) {

             if ((b & 0xFF) < 0x10)

                 hex.append("0");

             hex.append(Integer.toHexString(b & 0xFF));

         }  

         return hex.toString();

     }