kaptcha实现算式验证码

来源：互联网发布：三体文明等级知乎编辑：程序博客网时间：2024/06/06 04:33

1.新建一个Dynamic Web Project项目，里面新建一个servlet文件，还有两个jsp文件和一个xml文件，在lib里面加入要用到的jar包，然后导入。整体的框架图如下所示：

2.KaptchaServlet.java里面的代码如下所示：

import com.google.code.kaptcha.Producer;import com.google.code.kaptcha.util.Config;import java.awt.image.BufferedImage;import java.io.IOException;import java.util.Enumeration;import java.util.Properties;import javax.imageio.ImageIO;import javax.servlet.Servlet;import javax.servlet.ServletConfig;import javax.servlet.ServletException;import javax.servlet.ServletOutputStream;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class KaptchaServlet extends HttpServlet implements Servlet {private Properties props;private Producer kaptchaProducer;private String sessionKeyValue;public KaptchaServlet() {this.props = new Properties();this.kaptchaProducer = null;this.sessionKeyValue = null;}public void init(ServletConfig conf) throws ServletException {super.init(conf);ImageIO.setUseCache(false);Enumeration initParams = conf.getInitParameterNames();while (initParams.hasMoreElements()) {String key = (String) initParams.nextElement();String value = conf.getInitParameter(key);this.props.put(key, value);}Config config = new Config(this.props);this.kaptchaProducer = config.getProducerImpl();this.sessionKeyValue = config.getSessionKey();}public void doGet(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {resp.setDateHeader("Expires", 0L);resp.setHeader("Cache-Control", "no-store, no-cache, must-revalidate");resp.addHeader("Cache-Control", "post-check=0, pre-check=0");resp.setHeader("Pragma", "no-cache");resp.setContentType("image/jpeg");String capText = this.kaptchaProducer.createText();String s1 = capText.substring(0, 1);String s2 = capText.substring(1, 2);int r = Integer.valueOf(s1).intValue() + Integer.valueOf(s2).intValue();req.getSession().setAttribute(this.sessionKeyValue, String.valueOf(r));BufferedImage bi = this.kaptchaProducer.createImage(s1 + "+" + s2 + "=?");ServletOutputStream out = resp.getOutputStream();ImageIO.write(bi, "jpg", out);try {out.flush();} finally {out.close();}}}

3.index.jsp里面的代码如下图所示：

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>randomcode</title><script type="text/javascript">function changeR(node){node.src = "randomcode.jpg?time="+new Date().getTime() ;}</script></head><body><img alt="random" src="randomcode.jpg" onclick="changeR(this)" style="cursor: pointer;"><br><form action="check.jsp"><input type="text" name="r"><input type="submit" value="submit"></form></body></html>

4.check.jsp里面的代码如下所示：

<%@ page language="java" contentType="text/html; charset=UTF-8"pageEncoding="UTF-8"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>check</title></head><body><%String k = (String) session.getAttribute(com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY);String str = request.getParameter("r");if (k.equals(str)){out.print("验证成功！<br>");}else{out.print("验证失败！<br>");}out.print("正确的结果是：" + k + "<br>");out.print("你输入的结果是：" + str + "<br>");%></body></html>

5.web.xml里面的代码如下所示：

<?xml version="1.0" encoding="UTF-8"?><web-app version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"><!-- 登陆验证码Kaptcha 2--><servlet><servlet-name>Kaptcha</servlet-name><servlet-class>KaptchaServlet</servlet-class><init-param><description>图片边框，合法值：yes , no</description><param-name>kaptcha.border</param-name><param-value>yes</param-value></init-param><init-param><description>边框颜色，合法值： r,g,b (and optional alpha) 或者white,black,blue.</description><param-name>kaptcha.border.color</param-name><param-value>black</param-value></init-param><init-param><description>边框厚度，合法值：>0</description><param-name>kaptcha.border.thickness</param-name><param-value>1</param-value></init-param><init-param><description>图片宽 200</description><param-name>kaptcha.image.width</param-name><param-value>200</param-value></init-param><init-param><description>图片高 50</description><param-name>kaptcha.image.height</param-name><param-value>50</param-value></init-param><init-param><description>图片实现类</description><param-name>kaptcha.producer.impl</param-name><param-value>com.google.code.kaptcha.impl.DefaultKaptcha</param-value></init-param><init-param><description>文本实现类</description><param-name>kaptcha.textproducer.impl</param-name><param-value>com.google.code.kaptcha.text.impl.DefaultTextCreator</param-value></init-param><init-param><description>文本集合，验证码值从此集合中获取</description><param-name>kaptcha.textproducer.char.string</param-name><param-value>1234567890</param-value><!--<param-value>abcde2345678gfynmnpwx</param-value>--><!--<param-value>慕课网教程验证码实例</param-value> --></init-param><init-param><description>验证码长度 5</description><param-name>kaptcha.textproducer.char.length</param-name><param-value>2</param-value></init-param><init-param><description>字体 Arial, Courier</description><param-name>kaptcha.textproducer.font.names</param-name><param-value>Arial, Courier</param-value></init-param><init-param><description>字体大小 40px.</description><param-name>kaptcha.textproducer.font.size</param-name><param-value>40</param-value></init-param><init-param><description>字体颜色，合法值： r,g,b 或者 white,black,blue.</description><param-name>kaptcha.textproducer.font.color</param-name><param-value>black</param-value></init-param><init-param><description>文字间隔 2</description><param-name>kaptcha.textproducer.char.space</param-name><param-value>2</param-value></init-param><init-param><description>干扰实现类</description><param-name>kaptcha.noise.impl</param-name><param-value><!-- com.google.code.kaptcha.impl.NoNoise -->com.google.code.kaptcha.impl.DefaultNoise</param-value></init-param><init-param><description>干扰颜色，合法值： r,g,b 或者 white,black,blue.</description><param-name>kaptcha.noise.color</param-name><param-value>black</param-value></init-param><init-param><description>图片样式： 水纹com.google.code.kaptcha.impl.WaterRipple鱼眼com.google.code.kaptcha.impl.FishEyeGimpy阴影com.google.code.kaptcha.impl.ShadowGimpy</description><param-name>kaptcha.obscurificator.impl</param-name><param-value>com.google.code.kaptcha.impl.WaterRipple</param-value></init-param><init-param><description>背景实现类</description><param-name>kaptcha.background.impl</param-name><param-value>com.google.code.kaptcha.impl.DefaultBackground</param-value></init-param><init-param><description>背景颜色渐变，开始颜色</description><param-name>kaptcha.background.clear.from</param-name><param-value>green</param-value></init-param><init-param><description>背景颜色渐变，结束颜色</description><param-name>kaptcha.background.clear.to</param-name><param-value>white</param-value></init-param><init-param><description>文字渲染器</description><param-name>kaptcha.word.impl</param-name><param-value>com.google.code.kaptcha.text.impl.DefaultWordRenderer</param-value></init-param><init-param><description>session中存放验证码的key键</description><param-name>kaptcha.session.key</param-name><param-value>KAPTCHA_SESSION_KEY</param-value></init-param><init-param><description>The date the kaptcha is generated is put into theHttpSession. This is the key value for that item in thesession.</description><param-name>kaptcha.session.date</param-name><param-value>KAPTCHA_SESSION_DATE</param-value></init-param></servlet><servlet-mapping><servlet-name>Kaptcha</servlet-name><url-pattern>/randomcode.jpg</url-pattern></servlet-mapping><welcome-file-list><welcome-file>index.jsp</welcome-file></welcome-file-list></web-app>

6.在浏览器里面输入http://localhost:8080/KaptchaCode/index.jsp运行得到如下的结果：

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