package com.myt.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 javax.servlet.http.HttpSession;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;
@WebServlet("/createImage")
public class CreateImageServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//生成验证码图片
resp.setContentType("image/jpeg");
resp.setHeader("Pragma","No-cache");
resp.setHeader("Cache-Control","no-cache,no-store,must-revalidate");
resp.setDateHeader("Expires",0);
//创建画布
int width = 100;
int height = 40;
BufferedImage image = new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB);
//获取画笔
Graphics2D grah = (Graphics2D) image.getGraphics();
grah.setColor(getRandColor(200,250));
grah.fillRect(0,0,width,height);
grah.setColor(getRandColor(160,200));
Random r = new Random();
//干扰线
for (int i = 0; i < 20; i++) {
int x = r.nextInt(width);
int y = r.nextInt(height);
int x1 = r.nextInt(12);
int y1 = r.nextInt(12);
grah.drawLine(x,y,x+x1,y+y1);
}
//画出验证码
grah.setFont(new Font("Arial",Font.BOLD,24));
StringBuilder StringBuilder = new StringBuilder();
for(int i=0;i<4;i++){
String code = String.valueOf(r.nextInt(10));
StringBuilder.append(code);
grah.setColor((getRandColor(20,130)));
//字体
grah.drawString(code,20*i+10,28);
}
//把正确的验证码值放在会话中
HttpSession session = req.getSession();
session.setAttribute("code",StringBuilder.toString());
//释放图形对象
grah.dispose();
try {
ImageIO.write(image, "JPEG", resp.getOutputStream());
} catch (IOException e) {
e.printStackTrace();
}
//把图片放在response中
ImageIO.write(image,"JPEG",resp.getOutputStream());
resp.getOutputStream().flush();
resp.getOutputStream().close();
resp.flushBuffer();
}
/**
* 随机范围生成颜色对象
* @return
*/
private Color getRandColor(int min,int max){
min = Math.min(min,255);
max = Math.min(max,255);
Random random = new Random();
int r = min+random.nextInt(max-min);
int g = min+random.nextInt(max-min);
int b = min+random.nextInt(max-min);
return new Color(r,g,b);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
this.doGet(req, resp);
}
}
```html
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
<head>
<meta charset="UTF-8">
<title>教务管理系统</title>
<%--加载了boostrap样式库--%>
<link rel="stylesheet" href="${pageContext.request.contextPath}/css/bootstrap.min.css"/>
<%--自定义的JS代码--%>
<script type="text/javascript">
function refresh() {
//点击是应该再次请求，重新画一张图片
var imgEle = document.getElementById("codeimage");//获取id获取图片标签对象
imgEle.src = "${pageContext.request.contextPath}/createImage?" + new Date();//使用new Date（）实现路径的刷新，预防缓存中图片重新加载
}
</script>
<style type="text/css">
body {
background-image: url('${pageContext.request.contextPath}/image/bg1.jpg');
background-size: cover;
}
.card {
margin-top: 85px;
background-color: rgba(0, 0, 0, 0.3);
}
</style>
</head>
<body>
<div class="container" align="center">
<div class="card col-6 p-5 ">
<h1>教务管理系统<sup>V1.0</sup></h1>
<div class="bg-info text-white p-2 mt-2" align="center">
<h4>用户登陆</h4>
</div>
<form class="form1" action="${pageContext.request.contextPath}/checkCode" method="post">
<div class="input-group mt-3">
<div class="input-group-prepend ">
<span class="input-group-text">用户名</span>
</div>
<input type="text" class="form-control" placeholder="请输入用户名" name="username" id="username"/>
</div>
<div class="input-group mt-3">
<div class="input-group-prepend ">
<span class="input-group-text">密码</span>
</div>
<input type="password" class="form-control" placeholder="请输入密码" id="password" name="password"/>
</div>
<div class="input-group mt-3">
<div class="input-group-prepend ">
<span class="input-group-text">请选择身份</span>
</div>
<select class="form-control" name="usertypes">
<option value="admin">管理员</option>
<option value="student">学生</option>
</select>
</div>
<span style="font-size:15px;color:red; ">
<%--page request session application--%>
${errorMsg}
</span>
<div class="input-group mt-3">
<div class="input-group-prepend ">
<span class="input-group-text">验证码</span>
</div>
<input type="text" class="form-control" placeholder="请输入验证码" name="code"/>
<img alt="验证码" src="${pageContext.request.contextPath}/createImage" onclick="refresh()" id="codeimage"
title="单击更换验证码"
style="height: 40px;margin-left: 5px;cursor: pointer;">
</div>
<span class="errorcode" style="font-size:15px; color:red;">${codeMsg}</span>
<br>
<button type="submit" class="btn btn-success w-100 mt-3">登陆</button>
<br/><br/>
<a href="${pageContext.request.contextPath}/public/register.jsp" class="btn btn-primary btn-sm"
role="button">没有账号？点击注册</a>
</form>
</div>
</div>
<script src="${pageContext.request.contextPath}/js/jquery-3.4.1.min.js"></script>
<script src="${pageContext.request.contextPath}/js/bootstrap.min.js"></script>
</body>
</html>
```
