public static void main(String[] args) throws NoSuchAlgorithmException {

       MessageDigest digest = MessageDigest.getInstance("md5");

       String password = "123456";

       byte [] result = digest.digest(password.getBytes());

       StringBuffer buffer  = new StringBuffer();

       for(byte b : result){

           //0xff是十六进制，十进制为255

          int nuber =  b & 0xff;

          String str = Integer.toHexString(nuber);

          if(str.length()==1){

             buffer.append("0");

          }

          buffer.append(str);

       }

       //这就是MD5加密得到的值

       System.out.println(buffer);

    }