拦截非法登录

仅需一个类

@WebFilter(urlPatterns = {"/**"})
public class myfilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException, IOException {
        HttpServletRequest httpServletRequest=(HttpServletRequest) servletRequest;
        System.out.println(httpServletRequest.getRequestURI());
        if(httpServletRequest.getRequestURI().equals("/stu/login")){
            filterChain.doFilter(servletRequest,servletResponse);
            System.out.println("合法请求");
        }
        Object user = httpServletRequest.getSession().getAttribute("user");
        if(user==null){
            System.out.println("非法请求");
            httpServletRequest.getRequestDispatcher("/jsp/login.jsp").forward(servletRequest,servletResponse);
        }else{
            filterChain.doFilter(servletRequest,servletResponse);
        }
    }

    @Override
    public void destroy() {

    }
}