oa系统禁止用户直接通过url去访问的页面

/**
 * @author chenfeng
 * 登陆系统拦截器，验证登陆
 */

public class LoginInterceptor implements HandlerInterceptor {
    private static Logger logger = LoggerFactory.getLogger(LoginInterceptor.class);
    @Override
    public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o) throws Exception {
        logger.info("====================拦截器启动======================");
        httpServletRequest.setAttribute("starttime",System.currentTimeMillis());

        HttpSession session=httpServletRequest.getSession();
        SystemUser systemUser= (SystemUser) session.getAttribute("loginUser");
        if (systemUser!=null){
            String s=httpServletRequest.getHeader("Referer");
            if (s==null){
                httpServletRequest.getRequestDispatcher("/login/toLogin").forward(httpServletRequest,httpServletResponse);
                return true;
            }else {
                return true;
            }

        }else {
            httpServletRequest.getRequestDispatcher("/login/toLogin").forward(httpServletRequest,httpServletResponse);
            return true;
        }
    }

    @Override
    public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {
        logger.info("===================执行处理完毕======================");
        long starttime= (long) httpServletRequest.getAttribute("starttime");
        httpServletRequest.removeAttribute("starttime");
        long endtime=System.currentTimeMillis();
        logger.info("=========请求地址:"+httpServletRequest.getRequestURI()+":处理时间:{}",(endtime-starttime)+"ms");
    }

    @Override
    public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {
        logger.info("=====================拦截器关闭=========================");
    }
}

先上代码，再来进行解释，