攔截器 ```java /** * 登陸檢查， */ public class LoginHandlerInterceptor implements HandlerInterceptor { //目標方法執行之前 @Override public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { Object user = request.getSession().getAttribute("loginUser"); if(user == null){ //未登陸，返回登陸頁面 request.setAttribute("msg","沒有權限請先登陸"); request.getRequestDispatcher("/index.html").forward(request,response); return false; }else{ //已登陸，放行請求 return true; } } @Override public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception { } @Override public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception { } } ``` 注冊攔截器 ```java //所有的WebMvcConfigurerAdapter組件都會一起起作用 @Bean //將組件注冊在容器 public WebMvcConfigurerAdapter webMvcConfigurerAdapter(){ WebMvcConfigurerAdapter adapter = new WebMvcConfigurerAdapter() { @Override public void addViewControllers(ViewControllerRegistry registry) { registry.addViewController("/").setViewName("login"); registry.addViewController("/index.html").setViewName("login"); registry.addViewController("/main.html").setViewName("dashboard"); } //注冊攔截器 @Override public void addInterceptors(InterceptorRegistry registry) { //super.addInterceptors(registry); //靜態資源； *.css , *.js //SpringBoot已經做好了靜態資源映射 registry.addInterceptor(new LoginHandlerInterceptor()).addPathPatterns("/**") .excludePathPatterns("/index.html","/","/user/login"); } }; return adapter; } ```