實現 HandlerInterceptor 介面

@Slf4j
public class LoginInterceptor implements HandlerInterceptor {

    /**
     * 目標方法執行之前
     * @param request
     * @param response
     * @param handler
     * @return
     * @throws Exception
     */
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {

        String requestURI = request.getRequestURI();
//        log.info("攔截的請求路徑",requestURI);

        HttpSession session = request.getSession();
        Object loginUser = session.getAttribute("loginUser");
        if(loginUser != null){
            return true;
        }
        request.setAttribute("msg","請先登入");
        request.getRequestDispatcher("/").forward(request,response);
        return false;
    }

    /**
     * 目標方法執行之後
     * @param request
     * @param response
     * @param handler
     * @param modelAndView
     * @throws Exception
     */
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {

    }

    /**
     * 頁面渲染以後
     * @param request
     * @param response
     * @param handler
     * @param ex
     * @throws Exception
     */
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {

    }
}
 

把該攔截器新增到 WebMvcConfigurer

@Configuration
public class AdminWebConfig implements WebMvcConfigurer {

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new LoginInterceptor())
                .addPathPatterns("/**")//所有請求都被攔截，包括靜態資源
                .excludePathPatterns("/","/login","/css/**","/fonts/**","/images/**","/js/**");//放行的請求
    }
}