Javaweb 登陆与验证码

　　本次记录分角色登陆以及验证码的Servlet。

1.登陆验证


<html>
<%--
  Created by IntelliJ IDEA.
  User: jiachenglin
  Date: 2022/11/11
  Time: 14:31
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<head>
    <title>Title</title>
</head>

<html>
<head>
    <title>顾客登陆</title>
    <h1 style="text-align: center">学生登陆</h1>
</head>
<body>
<form action="${pageContext.request.contextPath}/StudentServlet" method="post">
    <div style="color: red;text-align: center">${login_err}</div><br>//从Servlet中传回登陆错误信息
    学号:<input type="text" id="userne" name="id"  maxlength="20"><br> //maxlength是指此处最长输入20个字符
    <span id="ne_err" style="color: red;display:none">输入有误</span><br>
    <span id="ne_num" style="display: none">最长20位</span>
    密码:<input type="password" id="pswd" name="password"  maxlength="20"><br>
    <span id="pswd_err" style="color: red;display:none">输入有误</span><br>
    验证码:<input type="text" name="valistr">
    <image  src="code"  id="identity" onload="btn.disable=false;" style="cursor:pointer; vertical-align:middle"/>
    <input type="button" value="看不清，更换验证码" onclick="changeImageCode()" id="btn" ><br>
    <div style="color: red">${yan}</div><br>
    <input type="submit" value="登陆"><input type="reset" value="重制"><br>
    <input type="hidden" name="method" value="login"><br>
    <a href="index.jsp">点击返回</a>

</form>
<script type="text/javascript">
    <!--验证码切换-->
    function changeImageCode() {
        document.getElementById('btn').isDisabled=true;
        document.getElementById('identity').src='code?ts='+new Date().getTime();
    }

let ne_num=document.getElementById("ne_num");
ne_num.onblur=function (){
    let ne_num1=ne_num.value.trim();
    if(ne_num1.length==20){
        document.getElementById("ne_num").style.display='';
    }else{
        document.getElementById("ne_num").style.display='none';
    }
}


</script>
</body>
</html>
___________________________________________________________________________________________________________________
Servlet内容

case "login":
   String  id = request.getParameter("id");
   String password = request.getParameter("password");
    String cher = request.getParameter("valistr");
   String cher2 = request.getSession().getAttribute("randomCode").toString();
    List<Student> list1 = studentDao.login(id, password);
    if (list1.isEmpty()) {
        request.setAttribute("login_err", "用户名或密码错误");
        request.getRequestDispatcher("student.jsp").forward(request, response);
    } else if (!cher.toLowerCase().equals(cher2.toLowerCase())) {//校验验证码
        request.setAttribute("yan", "验证码不一致！");
        request.getRequestDispatcher("student.jsp").forward(request, response);
    } else {
        request.setAttribute("user", id);
        request.getRequestDispatcher("studentjm.jsp").forward(request, response);
    }
    break;

___________________________________________________________________________________________________________________


2.验证码Servlet

import javax.imageio.ImageIO;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
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.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

@WebServlet(name = "VerifyCodeServlet", urlPatterns = "/code")
public class VerifyCodeServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //防止浏览器缓存验证码
        response.setDateHeader("Expires",-1);
        response.setHeader("Cache-Control","no-Cache");
        response.setHeader("pragma","no-Cache");
        int width = 60;//验证码总宽度
        int height = 20;//验证码总高度
//         随机数
        char[] codeChar = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789".toCharArray();//字符串转换成字符数组
        String captcha = "";//定义一个临时路径
        Random random = new Random();//new 随机类Random
//         生成验证码图片
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
//         绘制矩形
        Graphics2D graphics = image.createGraphics();//绘制环境对象
        graphics.setColor(Color.WHITE);//背景色
        graphics.fillRect(0, 0, width, height);//绘制矩形
        Font font=new Font("Times New Roman",Font.PLAIN,18);
        graphics.setFont(font);
        //画边框
        graphics.setColor(Color.BLACK);
        graphics.drawRect(0,0,-1,-1);
        //随机产生160条干扰线
        graphics.setColor(Color.LIGHT_GRAY);
        for(int i=0;i<160;i++){
            int x=random.nextInt(width);
            int y=random.nextInt(height);
            int x1=random.nextInt(12);
            int y1=random.nextInt(12);
            graphics.drawLine(x,y,x+x1,y+y1);
        }
        //randomCode用于保存随机产生的验证码
        StringBuffer randomCode=new StringBuffer();
        int red=0,green=0,blue=0;
//         生成验证码图片
        for (int i = 0; i < 4; i++) {
            int strRand=random.nextInt(codeChar.length)+1;
            String s= String.valueOf(codeChar[strRand]);
            //产生随机的颜色分量来构造颜色值
            red=random.nextInt(110);
            green=random.nextInt(50);
            blue=random.nextInt(50);
            graphics.setColor(new Color(red,green,blue));
            graphics.drawString(s,13*i+6,16);
            randomCode.append(s);
//            int index = random.nextInt(codeChar.length);
//            // 设置验证码字体图片颜色
//            graphics.setColor(new Color(random.nextInt(110), random.nextInt(150), random.nextInt(200)));
//            // 每个验证码字体的宽间距，高度
//            graphics.drawString(codeChar[index] + "", (i * 20) + 15, 20);
//            captcha += codeChar[index];//把生成的验证码保存在临时变量中
        }
        //将四位验证码保存在session中
        HttpSession session= request.getSession();
        session.setAttribute("randomCode",randomCode.toString());
        //防止浏览器缓存验证码
        response.setDateHeader("Expires",-1);
        response.setHeader("Cache-Control","no-Cache");
        response.setHeader("pragma","no-Cache");
        response.setContentType("image/jpeg");
        ServletOutputStream sos=response.getOutputStream();
        // request.getSession().setAttribute("codes", captcha); //把验证码保存在Session对象中
//         利用ImageI0输出验证码
        ImageIO.write(image, "jpeg", sos);
        sos.close();

    }
}

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Javaweb 登陆与验证码

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