首页 > 编程语言 >Javaweb基础复习------Cookie+Session案例的实现（登录注册案例）

Javaweb基础复习------Cookie+Session案例的实现（登录注册案例）

时间：2022-10-29 21:56:46浏览次数：58  
标签：Javaweb resp req 案例 Session user import servlet javax

Cookie对象的创建--Cookie cookie=new Cookie("key","value");

发送Cookie：resp.addCookie();

获取Cookie数据：req.getCookie("","");

Cookie不能直接存储中文

需要进行转码：URL编码

String value=URLEncoding.encode(value,"utf-8");

解码：
String value=URLDecoding.decode(value,"utf-8");

登录注册案例实现

//用户登录
//登录界面的实现
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
  <head>
    <title>登录界面</title>
  </head>
  <body>
  <center>
    <form action="loginServlet" method="post">
      <h1 id="loginMsg">LOGIN</h1>
      <div id="errorMsg">${login_msg}</div>
      <tr>
        <td>用户名：</td>
        <td><input type="text" name="username" placeholder="请输入用户名"></td>
      </tr>
      <p>
      <tr>
        <td>密码：</td>
        <td><input type="text" name="password" placeholder="请输入密码"></td>
      </tr>
      <p>
      <tr>
        <input type="checkbox" name="remember">记住信息
      </tr>
      <p>
      <tr>
        <button type="submit" value="登录">登录</button>
      </tr>
    </form>
  </center>
  </body>
</html>
//显示界面的实现
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%--
  Created by IntelliJ IDEA.
  User: 12140
  Date: 2022/10/27
  Time: 14:29
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>浏览界面</title>
</head>
<body>
<center>
    <h1>${user.username},欢迎你！</h1>
    <table colspan="3">
    <tr>
        <td align="center">用户名</td>
        <td align="center">密码</td>
        <td align="center">学号</td>
    </tr>
    <c:forEach items="${list}" var="user">
        <tr>
        <td>${user.username}</td>
        <td>${user.password}</td>
        <td>${user.id}</td>
        </tr>
        </c:forEach>
    </table>
</center>
</body>
</html>


//后端界面的实现

//获取到前端输入的数据，并且进行判断该用户是否存在在数据库中
package org.example.serlvet;

import org.example.Bean.User;
import org.example.mapper.UserMapper;
import org.example.service.UserService;

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

@WebServlet("/loginServlet")
public class loginServlet extends HttpServlet {
    private UserService us=new UserService();

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("utf-8");
        resp.setContentType("text/html;charset=utf-8");

        String username=req.getParameter("username");
        String password=req.getParameter("password");

        User user=us.login(username,password);

        //判断
        if(user!=null){
            HttpSession hs=req.getSession();
            hs.setAttribute("user",user);
            String contentPath=req.getContextPath();
            resp.sendRedirect(contentPath+"/allServlet");
        }
        else{
            req.setAttribute("login_msg","用户名或者密码错误！");
            req.getRequestDispatcher("index.jsp").forward(req,resp);
        }


    }

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

//查询到数据库的表中的所有数据
package org.example.serlvet;

import org.example.Bean.User;
import org.example.service.UserService;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.List;

@WebServlet("/allServlet")
public class allServlet extends HttpServlet {
    private UserService us=new UserService();
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("utf-8");
        resp.setContentType("text/html;charset=utf-8");

        List<User> list=us.selectAll();

        req.setAttribute("list",list);
        req.getRequestDispatcher("look.jsp").forward(req,resp);
    }

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

登录界面的实现：

显示界面的实现：

用户登录时需要注意到的问题

在进行用户的登录操作时，发现若是想要实现在利用c:forEach标签之前，将文本框中获取到的数据先展示在jsp页面，那么，我们需要利用
session实现存储数据的状态，到时候方便拿出来用；
因为这次的用户登录案例，在两个jsp页面之间，有两个servlet.java文件进行跳转，数据跳转就没了，需要session将数据存储起来，
到时候直接在第二个jsp页面利用一下就好！

记住用户案例的实现（复选框------记住我）

再返回到登录界面，就会显示出数据保存到这里的结果：

用户注册案例的实现（用户名不可重复）

//UserService.java(里面存放各种操作的具体实现方法)
//用户注册(添加)
    public void add(User user){
        SqlSession sqlSession=sf.openSession();

        UserMapper us=sqlSession.getMapper(UserMapper.class);

        us.add(user);

        sqlSession.commit();

    }

    //用户判断注册
    public boolean register(User user){
        SqlSession sqlSession=sf.openSession();

        UserMapper us=sqlSession.getMapper(UserMapper.class);

        User u=us.selectByUsername(user.getUsername());

        if(u==null){
            //可以注册
            us.add(user);
            sqlSession.commit();
        }
        sqlSession.close();

        return u==null;
    }

//register.java(注册功能的具体实现方法)
package org.example.serlvet;

import org.example.Bean.User;
import org.example.service.UserService;

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

@WebServlet("/registerServlet")
public class registerServlet extends HttpServlet {

    private UserService us=new UserService();
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("utf-8");
        resp.setContentType("text/html;charset=utf-8");

        String username=req.getParameter("username");
        String password=req.getParameter("password");

        User user=new User();
        user.setUsername(username);
        user.setPassword(password);

        boolean flag=us.register(user);

        if(flag){
            req.setAttribute("register_msg","注册成功！请登录！");
            //req.setAttribute("user",user);
            req.getRequestDispatcher("index.jsp").forward(req,resp);
        }else{
            req.setAttribute("register_msg","注册失败！");
            req.getRequestDispatcher("register.jsp").forward(req,resp);
        }
    }

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


//注册界面
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>注册界面</title>
</head>
<body>
<center>
  <tr>
    已有账号？<a href="index.jsp">登录</a>
  </tr>
  <form action="registerServlet" method="post">
    <tr>
      <td>用户名：</td>
      <td><input type="text" name="username" placeholder="请输入用户名"></td>
      <br>
      <div id="errorUsername">${register_msg}</div>
    </tr>
    <p>
    <tr>
      <td>密码：</td>
      <td><input type="text" name="password" placeholder="请输入密码"></td>
    </tr>
    <p>
    <tr>
      <td>验证码：</td>
      <td><input type="text" name="yan" placeholder="请输入验证码"></td>
    </tr>
    <p>
    <tr>
      <button type="submit" value="提交">提交</button>
    </tr>
  </form>
</center>
</body>
</html>

若是数据库里面有与注册界面的那个username文本框里面的相同的数据，那么会显示注册不成功，需要重新注册！

验证码案例的实现

由于验证码用时较长，决定单独出一期，给足验证码“牌面”。
移步下一篇嗷！

标签：Javaweb,resp,req,案例,Session,user,import,servlet,javax
From： https://www.cnblogs.com/liuzijin/p/16829701.html

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