我最近在我的Sping Boot 应用程序中实现了带有Spring Security的JWT身份验证。

public class JWTAuthenticationFilter extends UsernamePasswordAuthenticationFilter {

  private AuthenticationManager authenticationManager;

  public JWTAuthenticationFilter(AuthenticationManager authenticationManager) {
    this.authenticationManager = authenticationManager;
  }

  @Override
  public Authentication attemptAuthentication(HttpServletRequest req, HttpServletResponse res)
      throws AuthenticationException {
    try {
      UserModel creds = new ObjectMapper().readValue(req.getInputStream(), UserModel.class);

      return authenticationManager.authenticate(
          new UsernamePasswordAuthenticationToken(creds.getMobileNumber(),
              creds.getPassword(), new ArrayList<>()));
    } catch (IOException e) {
      throw new RuntimeException(e);
    }
  }

  @Override
  protected void successfulAuthentication(HttpServletRequest req, HttpServletResponse res,
      FilterChain chain,
      Authentication auth) throws IOException, ServletException {

    String token = Jwts.builder().setSubject(((User) auth.getPrincipal()).getUsername())
        .setExpiration(new Date(System.currentTimeMillis() + 360000000))
        .signWith(SignatureAlgorithm.HS512, SecurityConstants.SECRET).compact();
    res.addHeader(SecurityConstants.HEADER_STRING, SecurityConstants.TOKEN_PREFIX + token);
    res.setStatus(HttpServletResponse.SC_OK);
    String tokenJsonResponse = new ObjectMapper().writeValueAsString("Ok");
    res.addHeader("Content-Type", "application/json");
    res.getWriter().print(tokenJsonResponse);
  }
}

我想在发送JWT之前向其添加角色。如何在JWT中添加角色？
我从代码中了解到，当登录请求到来时，它包含userName和password，ObjectMapper将其Map到指定的类之一。那么，我如何从数据库中提取该用户的角色呢？