用filter实现登陆验证

在点击有些资源时你需要先登录

点击查看代码

package servlet.filter;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;

@WebFilter("/*")
public class FilterDemo2 implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
       HttpServletRequest req =   (HttpServletRequest)   servletRequest;

        String requestURI = req.getRequestURI();
        //注意以后还要排除css/js/验证码等资源
        if(requestURI.contains("/login.jsp")||requestURI.contains("/loginServlet")){
            filterChain.doFilter(servletRequest,servletResponse);
        }else {
            Object user = req.getSession().getAttribute("user");
            if(user!=null){
                filterChain.doFilter(servletRequest,servletResponse);
            }else {
                req.setAttribute("login_msg","请先登录");
                req.getRequestDispatcher("/login.jsp").forward(req,servletResponse);
            }
        }


    }

    @Override
    public void destroy() {

    }
}