通过Session案例分析一次性验证码登录

验证码的实现原理：

在一个Servlet中生成验证，并把验证码上的数据保存在Session，用户提交验证码之后，会提交给另外一个Servlet程序。在获取用户提交数据的Servlet中的从Session中把验证码取出，在取出的同时从Session中把验证码删除。

1.注册页面：register.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

<%String path = request.getContextPath();

String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";

%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

<head>

<base href="<%=basePath%>" rel="external nofollow" >

<title>My JSP 'login.jsp' starting page</title>

<meta http-equiv="pragma" content="no-cache">

<meta http-equiv="cache-control" content="no-cache">

<meta http-equiv="expires" content="0">

<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">

<meta http-equiv="description" content="This is my page">

<!--

<link rel="stylesheet" type="text/css" href="styles.css" rel="external nofollow" >

-->

<script type="text/javascript">

function _changImg(){

document.getElementById("myimg").src = "/day11/checkImg?" + new Date().getMilliseconds();

}

</script>

</head>

<body>

<center>

<form action="/day11/regist" method="post">

<table>

<tr>

<td>用户名<font color="red">*</font></td>

<td><input type="text" name="name"/></td>

</tr>

<tr>

<td>密码</td>

<td><input type="password" name="password"/></td>

</tr>

<tr>

<td>输入验证码</td>

<td>

<input type="text" name="form_checkcode" />

<img style="cursor: pointer;" alt="" src="/day11/checkImg" id="myimg" onclick="_changImg();"/>

<a href="javascript:void(0);" rel="external nofollow" onclick="_changImg();">看不清，换一张</a>

<font color="red">${imgError }</font>

</td>

</tr>

<tr>

<td><input type="submit" value="注册" /></td>

</tr>

</table>

</form>

</center>

</body>

</html>

2.生成验证码参考：cn.itcast.session.CheckImgServlet

public class CheckImgServlet extends HttpServlet {

public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

int width = 120;

int height = 40;

// 先生成一张纸

BufferedImage bufi = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

// 画笔

Graphics g = bufi.getGraphics();

// 设置背景颜色

// 修改画笔颜色

g.setColor(Color.white);

// 填充

g.fillRect(0, 0, width, height);

// 绘制边框

// 设置边框颜色

g.setColor(Color.red);

// 画边框

g.drawRect(0, 0, width - 1, height - 1);

// 准备一些数据

String data = "ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890abcdefghijklmnopqrstuvwxyz";

// 生成随机对象

Random r = new Random();

String checkcode = "";

// 生成4个随机的数字

for (int i = 0; i < 4; i++) {

// 生成随机颜色

g.setColor(new Color(r.nextInt(255), r.nextInt(255), r.nextInt(255)));

// 设置字体

g.setFont(new Font("宋体", Font.ITALIC, 25));

String c = data.charAt(r.nextInt(data.length())) + "";

g.drawString(c, 10 + (20 * i), 30);

checkcode += c;

}

// 将生成的验证码放到 session中

request.getSession().setAttribute("session_checkcode", checkcode);

// 画干扰线

for (int i = 0; i < 8; i++) {

// 设置随机颜色

g.setColor(new Color(r.nextInt(255), r.nextInt(255), r.nextInt(255)));

// 画线两点确定一线

g.drawLine(r.nextInt(width), r.nextInt(height), r.nextInt(width), r.nextInt(height));

}

// 将图片输出到浏览器

ImageIO.write(bufi, "jpg", response.getOutputStream());

}

public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

}

3.验证码的验证参考：cn.itcast.session.RegistServlet

通过Session案例分析一次性验证码登录

相关文章

快网idc优惠网

相关文章

微信

快网idc优惠网

QQ交流群