Cookie和Session

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关于用Cookie和Session改进项目代码

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import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.Cookie;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;

import java.io.IOException;
@WebServlet("/cookie")
public class CookieServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        Cookie productId = new Cookie("pw", "math");
        productId.setMaxAge(60*60);
        productId.setPath("/cookie");//在cookie路径和其中子路径
        response.addCookie(productId);
    }
}

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package com.xiaoguan.oa.dept.web;

import com.xiaoguan.oa.dept.utils.DBUtil;
import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.*;

import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

@WebServlet({"/login","/logout"})
public class UserServlet extends HttpServlet {
    @Override
    protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String servletPath = request.getServletPath();
        if("/login".equals(servletPath)){
            doLogin(request,response);
        } else if ("/logout".equals(servletPath)) {
            doLogout(request,response);
        } else{
            System.out.println("用户Servlet操作错误");
        }
    }

    private void doLogout(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        HttpSession session = request.getSession(false);
        if(session!=null){
            session.invalidate();
            response.sendRedirect(request.getContextPath()+"/index.jsp");
        }
    }

    protected void doLogin(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String userName = request.getParameter("userName");
        String userPassword = request.getParameter("userPassword");
        Connection conn=null;
        PreparedStatement ps=null;
        ResultSet rs=null;
        boolean flag=false;
        int id=0;
        try {
            conn= DBUtil.getConnection();
            String sql="select id from login where 登录名=? and 登录密码=?";
            ps=conn.prepareStatement(sql);
            ps.setString(1,userName);
            ps.setString(2,userPassword);
            rs=ps.executeQuery();
            if(rs.next()){
                flag=true;
                id=rs.getInt("id");
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            DBUtil.close(conn,ps,rs);
        }
        if(flag){
            HttpSession session = request.getSession();
            session.setAttribute("id",id);
            session.setAttribute("userName",userName);
            if("1".equals(request.getParameter("flag")))
            {
                Cookie userNameLoginCookie = new Cookie("userName", userName);
                Cookie userPasswordLoginCookie = new Cookie("userPassword", userPassword);
                userNameLoginCookie.setMaxAge(60*60*24*10);
                userPasswordLoginCookie.setMaxAge(60*60*24*10);
                userNameLoginCookie.setPath(request.getContextPath());
                userPasswordLoginCookie.setPath(request.getContextPath());
                response.addCookie(userNameLoginCookie);
                response.addCookie(userPasswordLoginCookie);
            }
            response.sendRedirect(request.getContextPath()+"/list");
        }else{
            response.sendRedirect(request.getContextPath()+"/error.jsp");
        }
    }
}

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package com.xiaoguan.oa.dept.web;

import com.xiaoguan.oa.dept.utils.DBUtil;
import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.*;

import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

@WebServlet("/welcome")
public class WelcomeServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        Cookie[] cookies = request.getCookies();
        String userPassword=null;
        String userName=null;
        if (cookies != null) {
            for (Cookie cookie : cookies) {
                String name = cookie.getName();
                if("userName".equals(name)){
                     userName = cookie.getValue();
                }
                if("userPassword".equals(name)){
                     userPassword = cookie.getValue();
                }
            }
        }
        if(userName!=null&&userPassword!=null){
            Connection conn=null;
            PreparedStatement ps=null;
            ResultSet rs=null;
            boolean flag=false;
            int id=0;
            try {
                conn= DBUtil.getConnection();
                String sql="select id from login where 登录名=? and 登录密码=?";
                ps=conn.prepareStatement(sql);
                ps.setString(1,userName);
                ps.setString(2,userPassword);
                rs=ps.executeQuery();
                if(rs.next()){
                    flag=true;
                    id=rs.getInt("id");
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }finally {
                DBUtil.close(conn,ps,rs);
            }
            if(flag) {
                HttpSession session = request.getSession();
                session.setAttribute("id", id);
                session.setAttribute("userName", userName);
                response.sendRedirect(request.getContextPath() + "/list");
            }else {
                response.sendRedirect(request.getContextPath()+"/index.jsp");
            }
        }else{
            response.sendRedirect(request.getContextPath()+"/index.jsp");
        }
    }
}

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package com.xiaoguan.oa.dept.web;

import com.xiaoguan.oa.dept.bean.Dept;
import com.xiaoguan.oa.dept.utils.DBUtil;
import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import jakarta.servlet.http.HttpSession;

import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

@WebServlet({"/list","/detail","/delete","/add","/modify"})
public class DeptServlet extends HttpServlet {
    @Override
    protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        HttpSession session = request.getSession(false);
        if(session!=null&&session.getAttribute("id")!=null){
            String servletPath = request.getServletPath();
            if("/list".equals(servletPath)){
                doList(request,response);
            } else if ("/detail".equals(servletPath)) {
                doDetail(request,response);
            } else if ("/delete".equals(servletPath)) {
                doDel(request,response);
            } else if ("/add".equals(servletPath)) {
                doAdd(request,response);

            } else if ("/modify".equals(servletPath)) {
                doModify(request,response);
            } else {
                System.out.println("路径有误！");
            }
        } else {
            response.sendRedirect(request.getContextPath()+"/welcome");
        }
    }

    private void doModify(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        String deptno = request.getParameter("deptno");
        String dname = request.getParameter("dname");
        String loc = request.getParameter("loc");
        Connection conn=null;
        PreparedStatement ps=null;
        int count=0;
        try {
            conn= DBUtil.getConnection();
            String sql="update dept set dname=?,loc=? where deptno=?";
            ps=conn.prepareStatement(sql);
            ps.setString(3,deptno);
            ps.setString(1,dname);
            ps.setString(2,loc);
            count=ps.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            DBUtil.close(conn,ps,null);
        }
        if(count==1){
            response.sendRedirect(request.getContextPath()+"/list");
        }else {
            response.sendRedirect(request.getContextPath()+"/error.jsp");
        }
    }

    private void doAdd(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        String deptno = request.getParameter("deptno");
        String dname = request.getParameter("dname");
        String loc = request.getParameter("loc");
        Connection conn=null;
        PreparedStatement ps=null;
        int count=0;
        try {
            conn= DBUtil.getConnection();
            String sql="insert into dept(deptno,dname,loc) values(?,?,?)";
            ps=conn.prepareStatement(sql);
            ps.setString(1,deptno);
            ps.setString(2,dname);
            ps.setString(3,loc);
            count=ps.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            DBUtil.close(conn,ps,null);
        }
        if(count==1){
            response.sendRedirect(request.getContextPath()+"/list");
        }else {
            response.sendRedirect(request.getContextPath()+"/error.jsp");
        }
    }

    private void doDel(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String deptno = request.getParameter("deptno");
        Connection conn=null;
        PreparedStatement ps=null;
        ResultSet rs=null;
        int count=0;
        try {
            conn=DBUtil.getConnection();
            String sql="delete from dept where deptno=?";
            ps=conn.prepareStatement(sql);
            ps.setString(1,deptno);
            count=ps.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            DBUtil.close(conn,ps,rs);
        }
        if(count==1){
            response.sendRedirect(request.getContextPath()+"/list");
        }else {
            response.sendRedirect(request.getContextPath()+"/error.jsp");
        }
    }

    private void doDetail(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String deptno = request.getParameter("deptno");
        String flag = request.getParameter("f");
        Connection conn=null;
        PreparedStatement ps=null;
        ResultSet rs=null;
        Dept dept=null;
        try {
            conn=DBUtil.getConnection();
            String sql="select dname,loc from dept where deptno=?";
            ps=conn.prepareStatement(sql);
            ps.setString(1,deptno);
            rs=ps.executeQuery();
            if(rs.next()){
                String dname = rs.getString("dname");
                String loc = rs.getString("loc");
                dept=new Dept(deptno,dname,loc);
                request.setAttribute("dept",dept);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            DBUtil.close(conn,ps,rs);
        }
        if("d".equals(flag)){
            request.getRequestDispatcher("/detail.jsp").forward(request,response);
        } else if ("m".equals(flag)) {
            request.getRequestDispatcher("/edit.jsp").forward(request,response);
        }else {
            System.out.println("f传参参数有误！");
        }

    }

    private void doList(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        List<Dept> depts = new ArrayList<>();
        Connection conn=null;
        PreparedStatement ps=null;
        ResultSet rs=null;
        try {
            conn=DBUtil.getConnection();
            String sql="select deptno,dname,loc from dept";
            ps= conn.prepareStatement(sql);
            rs=ps.executeQuery();
            while (rs.next()) {
                String deptno=rs.getString("deptno");
                String dname = rs.getString("dname");
                String loc=rs.getString("loc");
                Dept dept=new Dept(deptno,dname,loc);
                depts.add(dept);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            DBUtil.close(conn,ps,rs);
        }
        request.setAttribute("deptList",depts);
        request.getRequestDispatcher("/list.jsp").forward(request,response);
    }
}

在XML里设置session存在时间代码

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<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="https://jakarta.ee/xml/ns/jakartaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="https://jakarta.ee/xml/ns/jakartaee https://jakarta.ee/xml/ns/jakartaee/web-app_6_0.xsd"
         version="6.0">
    <!--session超时时长为30分钟-->
    <welcome-file-list>
        <welcome-file>/welcome</welcome-file>
    </welcome-file-list>
    <session-config>
        <session-timeout>30</session-timeout>
    </session-config>
</web-app>