实现登陆校验- Filter过滤器

Q：这个人没有登陆，我不想让ta访问我的页面

A：简单实现

先创建一个Filter过滤器

1. 起名为LoginCheckFilter ，然后实现Filter 接口

   /**
    * @author JUNHAO
    * 检查用户是否已经登陆
    */
   @WebFilter(filterName = "LoginCheckFilter", urlPatterns = "/*")
   @Slf4j
   @Component
   public class LoginCheckFilter implements Filter {
       /**
        * 路径匹配器，支持通配符
        */
       public static final AntPathMatcher PATH_MATCHER = new AntPathMatcher();
       @Override
       public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
           HttpServletRequest request = (HttpServletRequest)servletRequest;
           HttpServletResponse response = (HttpServletResponse) servletResponse;
           // 获取本次请求路径
           String requestURI = request.getRequestURI();
           // 哪些请求不需要处理
           String[] urls = new String[] {
                   "/employee/login",
                   "/backend/**",
                   "/front/**"
           };
           // 判断本次请求是否需要处理
           boolean check = check(requestURI, urls);
           //不需要处理，直接放行
           if (check) {
               log.info("本次请求不需要处理");
               filterChain.doFilter(request, response);
               return;
           }
           // 判断登陆状态，如果已登录，直接放行
           if (request.getSession().getAttribute("employee") != null) {
               filterChain.doFilter(request, response);
               log.info("已登录，放行");
               return;
           }
           // 未登录，返回未登录结果，通过输出流方式向客户端响应数据
           response.getWriter().write(JSON.toJSONString(R.error("NOTLOGIN")));
           log.info("未登录");
           return;
   
   
       }
   
       /**
        * 检查本次请求是否需要放行
        * @param requestURI
        * @param urls
        * @return
        */
       public boolean check(String requestURI, String[] urls) {
           for (String url : urls) {
               boolean match = PATH_MATCHER.match(url, requestURI);
               if (match) {
                   return true;
               }
           }
           return false;
       }
   }
   

   emd…