案例_验证码
案例需求：
- 访问带有验证码的登录页面login.jsp
- 用户输入用户名 密码以及验证码
-
- 如果用户名和密码输入有误 跳转登录页面 提示：用户名或密码错误
- 如果验证码输入有误 跳转登录页面 提示 验证码错误
- 如果全部输入正确 则跳转到主页success.jsp 显示：用户名，欢迎您
分析
java代码
验证码
package com.bai.Servlet;
import javax.imageio.ImageIO;
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.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;
@WebServlet("/CheckCodeServlet")
public class CheckCodeServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
int width = 100;
int height = 50;
//1.创建一对象 在内存中图片（验证码图片对象）
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
//2.美化图片
//2.1填充背景色
Graphics g = image.getGraphics();//画笔对象
g.setColor(Color.PINK);
g.fillRect(0,0,width,height);
//2.2画边框
g.setColor(Color.BLUE);
g.drawRect(0,0,width-1 ,height-1);
String str="ABCDEFGHIJLMNOPQRTUVWXYZabcdefghigklmnopqstuvwxyz0123456789";
//生成随机角标
Random ran = new Random();
StringBuilder sb = new StringBuilder();
for (int i=1;i<=4;i++){
int index=ran.nextInt(str.length());
//获取字符
char ch = str.charAt(index);//随机字符
sb.append(ch);
//2.3写验证码
g.drawString(ch+"",width/5*i,height/2);
}
String checkCode_session = sb.toString();
//将验证码存入session
req.getSession().setAttribute("checkCode_session",checkCode_session);
//2.4画干扰线
g.setColor(Color.GREEN);
//随机生成坐标点
for (int i = 0; i < 10; i++) {
int x1=ran.nextInt(width);
int x2=ran.nextInt(width);
int y1=ran.nextInt(height);
int y2=ran.nextInt(height);
g.drawLine(x1,x2,y1,y2);
}
//3.将图片输出到页面展示
ImageIO.write(image,"jpg",resp.getOutputStream());
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doGet(req, resp);
}
}
登录页面
<%--
Created by IntelliJ IDEA.
User: Administrator
Date: 2022/8/16
Time: 10:54
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>login</title>
<script>
window.onload=function () {
document.getElementById("img").onclick=function () {
this.src="/CheckCodeServlet?time="+new Date().getTime();
}
}
</script>
<style>
div{
color:red;
}
</style>
</head>
<body>
<form action="/loginServlet" method="post">
<table>
<tr>
<td>用户名</td>
<td><input type="text" name="username"></td>
</tr>
<tr>
<td>密码</td>
<td><input type="password" name="password"></td>
</tr>
<tr>
<td>验证码</td>
<td><input type="text" name="checkCode"></td>
</tr>
<tr>
<td colspan="2"><img id="img" src="/CheckCodeServlet"></td>
</tr>
<tr>
<td colspan="2"><input type="submit" name="登录"></td>
</tr>
</table>
</form>
<div><%=request.getAttribute("cc_error")==null ? "" :request.getAttribute("cc_error")%></div>
<div><%=request.getAttribute("login_error")==null ? "" :request.getAttribute("login_error")%></div>
</body>
</html>
业务层
package com.bai.Servlet;
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 {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//设置request编码
req.setCharacterEncoding("utf-8");
//获取参数
String username = req.getParameter("username");
String password = req.getParameter("password");
String checkCode = req.getParameter("checkCode");
//获取生成的验证码
HttpSession session = req.getSession();
String checkCode_session = (String) session.getAttribute("checkCode_session");
//判断验证码是否正确
if (checkCode_session.equals(checkCode)) {
//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 ("zhangsan".equals(username) && "123".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
resp.sendRedirect(req.getContextPath() + "/success.jsp");
} else {
//登录失败
//存储提示信息到request
req.setAttribute("login_error", "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("cc_error","验证码错误");
//转发到登录页面
req.getRequestDispatcher("/login.jsp").forward(req,resp);
}
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doGet(req, resp);
}
}
登录成功页面
<%--
Created by IntelliJ IDEA.
User: Administrator
Date: 2022/8/16
Time: 11:52
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>
<h1><%=request.getSession().getAttribute("user")%>,欢迎您</h1>
</body>
</html>
运行结果
登录页面
验证码输入错误
用户名和密码输入错误
登录成功
