Servlet + Session 验证码登录
Servlet + Session 验证码登录
Maven下新建Module，选定WebApp，修改groupID，设置name=login_check_code
Project Structure
[外链图片转存失败,源站可能有防盗链机制,建议将图片保存下来直接上传(img-lRMoB140-1594283791006)(G:\Github_code\md_photos\20200709160521847.png)]
修改web.xml文件
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee
http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
version="4.0">
web-app>
在webapp下新建css文件夹，放入css全局样式
登录界面：login.jsp
<%--
Created by IntelliJ IDEA.
User: PitYk
Date: 2020/2/22
Time: 11:35
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
管理员登录
管理员登录
${login_msg}
登录成功页面：success.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Titletitle>
head>
<body>
<h1><%=request.getSession().getAttribute("user")%>,欢迎您h1>
body>
html>
验证码生成CheckCodeServlet
package main.com.web;
@WebServlet("/checkCodeServlet")
public class CheckCodeServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("进入CheckCodeServlet代码文件！");
//服务器通知浏览器不要缓存
response.setHeader("pragma","no-cache");
response.setHeader("cache-control","no-cache");
response.setHeader("expires","0");
//在内存中创建一个长80，宽30的图片，默认黑色背景
//参数一：长
//参数二：宽
//参数三：颜色
int width = 80;
int height = 30;
BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
//获取画笔
Graphics g = image.getGraphics();
//设置画笔颜色为灰色
g.setColor(Color.GRAY);
//填充图片
g.fillRect(0,0, width,height);
//产生4个随机验证码，12Ey
String checkCode = getCheckCode();
//将验证码放入HttpSession中
request.getSession().setAttribute("CHECKCODE_SERVER",checkCode);
//设置画笔颜色为黄色
g.setColor(Color.YELLOW);
//设置字体的小大
g.setFont(new Font("黑体",Font.BOLD,24));
//向图片上写入验证码
g.drawString(checkCode,15,25);
//将内存中的图片输出到浏览器
//参数一：图片对象
//参数二：图片的格式，如PNG,JPG,GIF
//参数三：图片输出到哪里去
ImageIO.write(image,"PNG",response.getOutputStream());
}
/**
* 产生4位随机字符串
*/
private String getCheckCode() {
int codelength = 4;
String base = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
int size = base.length();
Random r = new Random();
StringBuffer sb = new StringBuffer();
for(int i=1;i<=codelength;i++){
//产生0到size-1的随机值
int index = r.nextInt(size);
//在base字符串中获取下标为index的字符
char c = base.charAt(index);
//将c放入到StringBuffer中去
sb.append(c);
}
System.out.println("验证码:" + sb);
return sb.toString();
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
this.doGet(req, resp);
}
}
用户登录LoginServlet
package main.com.web;
@WebServlet("/loginServlet")
public class LoginServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
this.doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
System.out.println("进入LoginServlet代码文件！");
//1.设置request编码
req.setCharacterEncoding("utf-8");
//2.获取参数
String username = req.getParameter("username");
String password = req.getParameter("password");
String verifycode = req.getParameter("verifycode");
System.out.println(username);
System.out.println(password);
//3.先获取生成的验证码
HttpSession session = req.getSession();
String checkCode_session = (String) session.getAttribute("CHECKCODE_SERVER");
//删除session中存储的验证码
session.removeAttribute("CHECKCODE_SERVER");
//3.先判断验证码是否正确
if(checkCode_session!=null &&checkCode_session.equalsIgnoreCase(verifycode)){
//忽略大小写比较
//验证码正确
//判断用户名和密码是否一致
if("admin".equals(username) && "123456".equals(password)){//需要调用UserDao查询数据库
//登录成功
//存储信息，用户信息
session.setAttribute("user",username);
//重定向到success.jsp
resp.sendRedirect(req.getContextPath()+"/success.jsp");
}else{
//登录失败
//存储提示信息到request
req.setAttribute("login_msg","用户名或密码错误");
//转发到登录页面
req.getRequestDispatcher("/login.jsp").forward(req,resp);
}
}else{
//验证码不一致
//存储提示信息到request
req.setAttribute("login_msg","验证码错误");
//转发到登录页面
resp.sendRedirect(req.getContextPath()+"/login.jsp");
}
}
}
index.jsp页面跳转
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%--<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>--%>
文本信息管理系统
Hello World!
5秒后自动跳转到界面
<%--content后数字表示等待时间秒数--%>
跳转到登录界面
登陆
验证码失败、密码错误
