升级自：

import org.springframework.security.authentication.encoding.PasswordEncoder;

    @Override
    public String encodePassword(String plainPassword, Object salt) {
        final String finalSalt = salt != null ? salt.toString() : "";
        return DigestUtils.md5Hex(finalSalt + plainPassword);
    }

    @Override
    public boolean isPasswordValid(String encodedPassword, String plainPassword, Object salt) {
        final String enteredPassword = encodePassword(plainPassword, salt);
        return encodedPassword.equals(enteredPassword);
    }

致：

import org.springframework.security.crypto.password.PasswordEncoder;

    @Override
    public String encode(CharSequence rawPassword) {
      final String finalSalt = salt != null ? salt.toString() : "";
      return DigestUtils.md5Hex(finalSalt + plainPassword);
    }

    @Override
    public boolean matches(CharSequence rawPassword, String encodedPassword) {
       final String enteredPassword = encodePassword(plainPassword, salt);
       return encodedPassword.equals(enteredPassword);
    }

不知道该怎么办 salt ?
我不知道我是否可以转换 rawPassword 到 String 取代 plainPassword ?