Java-JSP+Cookie+Session改造登录
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实现功能：
- 验证码
- 保存用户名和密码
- 提示登录错误信息
第一步定义接口，实现登录的方法
package com.mappers;
import com.pojo.Customer;
import org.apache.ibatis.annotations.Param;
public interface CustomerMapper
public Customer login(@Param("name") String name, @Param("pass")String password);
第二步在mapper里写SQL语句
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.mappers.CustomerMapper">
<select id="login" resultType="com.pojo.Customer">
select * from customer where name=#name and password=#pass
</select>
</mapper>
第三步实现service方法，实现三层架构模式
public class CustomerService
public boolean loginService(String name,String password)
SqlSession session = Utils.getSession();
Customer login = session.getMapper(CustomerMapper.class).login(name, password);
if(login==null)
return false;
return true;
第四步实现servlet
package com.Controller;
import com.Service.CustomerService;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
@WebServlet("/login")
public class loginServlet extends HttpServlet
CustomerService customerService = new CustomerService();
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException
resp.setContentType("text/html;charset=utf-8");
String username = req.getParameter("username");
String password = req.getParameter("password");
//获取请求验证码的参数
String checkCode = req.getParameter("captcha");
//获取生成的验证码
//session的应用场景，将servlet生成的验证码存储到session中。
String savedCode = (String) req.getSession().getAttribute(
"captcha");
//检验验证码是否正确，验证码不区分大小写
String error=null;
if(savedCode.equalsIgnoreCase(checkCode))
if(username!=null&&username!=""&&password!=null&&password!="")
boolean login =customerService.loginService(username,password);
if(login)
//利用cookie保存用户名和密码
String remember = req.getParameter("remember");
if(remember!=null)
Cookie cookie = new Cookie("name",username);
cookie.setPath(req.getContextPath());
cookie.setMaxAge(15*24*60*60);
resp.addCookie(cookie);
Cookie cookie2 = new Cookie("pass",password);
cookie2.setPath(req.getContextPath());
cookie2.setMaxAge(15*24*60*60);
resp.addCookie(cookie2);
req.getRequestDispatcher("/success.jsp").forward(req,resp);
else
error="用户名或者密码错误";
req.setAttribute("error",error);
req.getRequestDispatcher("login.jsp").forward(req,resp);
else
error="用户名或者密码为空";
req.setAttribute("error",error);
req.getRequestDispatcher("login.jsp").forward(req,resp);
error="验证码错误";
req.setAttribute("error",error);
req.getRequestDispatcher("login.jsp").forward(req,resp);
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException
doGet(req, resp);
最后前端代码
<%--
Created by IntelliJ IDEA.
User: 86133
Date: 2021/10/5
Time: 16:37
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<%String error = (String )request.getAttribute("error");
if(error==null)
error="";
String name=null;
String password=null;
Cookie[] cookies = request.getCookies();
for (Cookie c:cookies)
if(c!=null)
if(c.getName().equals("name"))
name=c.getValue();
if(name==null)
name="";
if(c.getName().equals("pass"))
password=c.getValue();
if(password==null)
password="";
%>
<div style="color: red"><%=error%></div>
<form action="/login" method="post" >
用户名: <input name="username" type="text" value="<%=name%>"/><br/>
密 码：<input name="password" type="password" value="<%=password%>"/><br/>
验证码：<input type="text" name="captcha">
<img src="/captcha" width="130px" height="48px" id="captcha" onClick="changeCaptche()"/><br>
<input type="checkbox" name="remember"/>记住用户名和密码<br>
<input type="submit" value="提交" /><br>
</form>
<script>
//用户点击图片实现切换图片
function changeCaptche()
console.log("点击图片了")
var imgElement = document.getElementById("captcha");
//因为当访问路径没有改变的时候，服务器会认为我们发送的是同一个请求，所以服务器会返回一个状态码304，所以服务器会从缓存中读取数据
//如果每次访问的URL有变化了，就不会从缓存中读取数据，因此可以在请求的地址后面加一个动态参数，例如时间日期。
imgElement.setAttribute("src","/captcha?date="+new Date())
</script>
</body>
</html>
提示错误信息
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