Springboot配置拦截器无法跳转登录页面

Springboot配置拦截器进行登录拦截时出现了“重定向的次数过多”，原因是拦截器配置全路径，无登录用户状态下一直被拦截，导致出现了死循环。

MyInterceptor ：

@Component
public class MyInterceptor implements HandlerInterceptor {
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        HttpSession session = request.getSession();
        if (session.getAttribute("userName") == null) {
            response.sendRedirect("/login.html");
            return false;
        } else {
            System.out.println("登录用户： " + session.getAttribute("userName"));
            return true;
        }
    }

    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("postHandle method is running!");
    }

    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("afterCompletion method is running!");
    }
}

MVCConfiguration ：

@Configuration
public class MVCConfiguration implements WebMvcConfigurer{

    @Autowired
    private MyInterceptor myInterceptor;
    /**
     * 重写接口中的addInterceptors方法，添加自定义拦截器
     * @param registry
     */
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(myInterceptor).addPathPatterns("/**");
    }
}

因为配置拦截的是全路径："/**"，所以当“MyInterceptor”判断“session.getAttribute("userName") == null”时重定向到“/login.html”时也会被“MVCConfiguration”拦截，所以又跳转回“MyInterceptor”，导致出现了死循环。

然后就页面报错如下图（转发也是类似道理，也是死循环）：

 解决办法：增添被排除的路径，对“MVCConfiguration”的拦截路径进行修改。

修改后的MVCConfiguration:

@Configuration
public class MVCConfiguration implements WebMvcConfigurer {

    @Autowired
    private MyInterceptor myInterceptor;

    /**
     * 重写接口中的addInterceptors方法，添加自定义拦截器
     *
     * @param registry
     */
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(myInterceptor).addPathPatterns("/**").excludePathPatterns("/login.html");
    }
}