MD5加密

MD5加密的本质就是把字符串的每个字节转化为int型再转化为对应的十六进制，然后存入StringBuilder中！

class Md5Utils {
        public static String getMD5String(String password) {
            try {
                MessageDigest digest = MessageDigest.getInstance("md5");
                byte[] result = digest.digest(password.getBytes());
                StringBuilder sb = new StringBuilder();
                for (byte b : result) {
                    int i = b & 0xff; // 加盐int i = b & 0xfe;
                    String str = Integer.toHexString(i);
                    if (str.length() == 1) {
                        sb.append("0");
                    }
                    sb.append(str);
                }
                return sb.toString();
            } catch (NoSuchAlgorithmException e) {
                e.printStackTrace();
                return "";
            }
        }
    }