1.專案結構

2.自定義攔截器

public class LoginHandlerlnterceptor implements HandlerInterceptor {
    //目標方法執行之前
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        Object loginname = request.getSession().getAttribute("loginname");
        
 
if(loginname==null||loginname.equals("")){
            //未登入，返回登陸介面
            request.setAttribute("msg","沒有許可權，請先登陸");
            //返回登陸page並且相應
           // response.sendRedirect("/index.html");
            request.getRequestDispatcher("/").forward(request,response);
            return false;
        }
 
else
        {
            //已經登陸,放行
            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 {

    }
}

3.攔截器加入mvc

public class Mymvc implements WebMvcConfigurer {
    //註冊攔截器
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        //springboot1已經做好了靜態資源映射了，可以訪問到
        registry.addInterceptor(new LoginHandlerlnterceptor()).addPathPatterns("/**").excludePathPatterns("/", "/user/logins", "/login.html").excludePathPatterns("/img/**",
                "/css/**", "/webjars/**");
    }

}
  

ok！                     還有不明白的可以下面留言