在BearerTokenAuthenticationFilter类中，添加以下代码：

@Override
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
        throws IOException, ServletException {
    HttpServletRequest request = (HttpServletRequest) req;
    String authorizationHeader = request.getHeader("Authorization");
    if (authorizationHeader == null || !authorizationHeader.startsWith("Bearer ")) {
        HttpServletResponse response = (HttpServletResponse) res;
        response.sendError(HttpServletResponse.SC_UNAUTHORIZED, "Unauthorized");
        return;
    }
    chain.doFilter(req, res);
}

这将检查请求中是否包含Authorization头，并检查其值是否为“Bearer”。如果没有，则返回401未授权HTTP响应。如果头是存在的并且具有正确的值，则继续处理链。通过添加这些检查，将禁止请求在缺少Authorization头的情况下通过BearerTokenAuthenticationFilter。