1.拦截器进行登录检查

/*登陆检查*/
//拦截器要注册到容器中
public class LoginHandlerInterceptor implements HandlerInterceptor {
    //目标方法执行之前
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        //获取session域，获取到loginUser，看是否登录
        HttpSession session = request.getSession();
        Object loginUser = session.getAttribute("loginUser");
        if (loginUser==null){
            //未登录，返回登录页面
            //获取转发器，并转发
            request.setAttribute("msg","没有权限请先登录");
            request.getRequestDispatcher("/index.html").forward(request,response);
            return false;
        }else {
            //已登录，放行
            return true;
        }
    }
}

@Configuration
public class MyMvcConfig implements WebMvcConfigurer {
    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
        //映射到login.html页面
        registry.addViewController("/").setViewName("login");
        registry.addViewController("/index.html").setViewName("login");
        //做重定向
        registry.addViewController("/main.html").setViewName("dashboard");
    }


    //将MyLocaleResolver加到注册
    @Bean
    public LocaleResolver localeResolver(){
        return new MyLocaleResolver();
    }

   //注册拦截器
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        //拦截器拦截所有请求，但放行以下请求
        registry.addInterceptor(new LoginHandlerInterceptor()).addPathPatterns("/**").excludePathPatterns("/","/index.html","/login.html","/user/login","/webjars/**","/asserts/**");
    }
}