工具类：MD5加密

    public class MD5Utils {
public static final String YAN = "sadf%^234h76UIywe7r8623j4h*&";

    /**
     * 对密码明文进行md5加密
     * @param passwrod
     * @return
     */
    public static String md5Encrypt(String passwrod){

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

            StringBuffer sb = new StringBuffer();

            byte[] encryptBytes = digest.digest((passwrod+YAN).getBytes());
            for (byte b : encryptBytes) {
                int i = b & 0xff; // 0xff 是   11111111  // 转换为无符号的整数

                String hexString = Integer.toHexString(i); // 转换为16进制

                if(hexString.length() == 1){  // 如果长度为1 前面补0
                    sb.append("0"+hexString);
                }else{
                    sb.append(hexString);
                }
            }
            return sb.toString();

        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
        return null;
    }
}