用户管理的小demo--登录校检

在user里面装session

1、 LoginServlet.java

2、LoginFilter.java

3、配置路径

结果：

在user里面装session

1、 LoginServlet.java

package com.by.servlet;

import com.by.pojo.User;
import com.by.service.UserService;
import com.by.service.impl.UserServiceImpl;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;

/**
 * 注意：
 *  1、一次只写一层
 *  2、复杂的代码先写注释，后写代码
 *  web层： 接受请求 控制跳转,   并调用service层
 */
public class LoginServlet extends HttpServlet {
    private UserService userService = new UserServiceImpl();

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        try{
            String username = req.getParameter("username");
            String password = req.getParameter("password");
            User user = userService.login(username,password);
            //控制页面的跳转
            if(user != null){ //登录成功

                //在user里面 装session : session 可以设置失效时间--浏览器进行关闭
                HttpSession session = req.getSession();
                session.setAttribute("user",user);
                session.setMaxInactiveInterval(60*30); //30分钟

                //利用重定向
                //重定向到selectServlet，在selectServlet查询数据，并把数据传递到main.jsp
                resp.sendRedirect("selectUser");
//                resp.sendRedirect("deleteUser");
            }else{
                resp.sendRedirect("login.jsp"); //登录失败 去登录页面
            }
        }catch (Exception e){
            e.printStackTrace();
        }
    }
}

2、LoginFilter.java

package com.by.filter;

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class LoginFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException {

        HttpServletRequest request = (HttpServletRequest) req;
        HttpServletResponse response = (HttpServletResponse) resp;

        //直接放行: “login.jsp”和“/”
        String uri = request.getRequestURI();
        if(uri.contains("login") || uri.endsWith("/")){
            System.out.println("uri:"+uri+"中包含login或以/结尾 --> 直接放行");
            //放行
            chain.doFilter(req,resp);
            //结束
            return;
        }

        //1、从session获取user
        Object user = request.getSession().getAttribute("user");

        //2、获取到user，则放行
        if(user != null){
            System.out.println("用户已登录 --> 直接放行");
            //放行
            chain.doFilter(req,resp);
            //结束
            return;
        }else{
            System.out.println("用户未登录 --> 重定向到 login.jsp");
            //3、没有获取到user，则重定向到login.jsp
            response.sendRedirect("login.jsp");
        }
    }

    @Override
    public void destroy() {

    }
}