当从Angular 16向Java REST API发出请求时，我在头中接收的令牌为null。但是，如果我向Postman提出请求，它会完美地工作。
我有一个Angular的前端和一个Java的后端。Java部分通过Spring Security，OAuth2和JWT进行保护。一旦我在Angular中执行登录并检索令牌，我就试图通过在请求头中发送令牌来获取用户列表。在检查Java时，我总是发现令牌是空的。下面是Angular请求

private urlEndPointUsuarios: string = 'http://localhost:8080/api/usuarios';

  constructor(private http: HttpClient, public router: Router,
    public authService: AuthService) { }

  private agregarAuthorizationHeader() {
     let token = this.authService.token;
     if (token != null) {
      this.httpHeaders = this.httpHeaders.append('Authorization', 'Bearer ' + token);
       return this.httpHeaders;
     }
     return this.httpHeaders;
  }

  getUsuarios(): Observable<Usuario[]> {
    return this.http.get(this.urlEndPointUsuarios, { headers: this.agregarAuthorizationHeader()}).pipe(
      map(response => response as Usuario[])
    )
  }

接下来，接收请求并检查令牌的Java方法如下：

@Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {
        String authHeader = request.getHeader("Authorization");
        String token = null;
        String username = null;
        
        if (authHeader != null && authHeader.startsWith("Bearer ")) {
            token = authHeader.substring(7);
            username = jwtService.extractUsername(token);
        }

        if (username != null && SecurityContextHolder.getContext().getAuthentication() == null) {
            UserDetails userDetails = userDetailsService.loadUserByUsername(username);
            if (jwtService.validateToken(token, userDetails)) {
                UsernamePasswordAuthenticationToken authToken = new UsernamePasswordAuthenticationToken(userDetails, null, userDetails.getAuthorities());
                authToken.setDetails(new WebAuthenticationDetailsSource().buildDetails(request));
                SecurityContextHolder.getContext().setAuthentication(authToken);
            }
        }
        filterChain.doFilter(request, response);
    }

另一方面，如果我用令牌向Postman发出请求，它会完美地工作。我可以看到我如何在Java中接收令牌，我可以在Postman中查看用户列表。我很感激你的帮助。谢谢