使用开源工具制作网页验证码的方法
2016年11月26日
开发工具：eclipse、kaptcha-2.3.jar包。
一、创建Web项目；
二、新建一个Jsp页面（内容有，一个文本框，一个图片容器，一个提交按钮)
<body> <img src="randomcode.jpg" onclick="changeR(this)" style="cursor: pointer;"> <form action="check.jsp"> <input type="text" name="r"> <input type="submit" value="s"> </form> </body>三、可以看出图片验证码来源（src=“randomcode.jpg”）需配置Web.xml文件。（交给Servlet（该servlet在kaptcha-2.3.jar）处理）
<servlet> <servlet-name>Kaptcha</servlet-name> <servlet-class>com.google.code.kaptcha.servlet.KaptchaServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>Kaptcha</servlet-name> <url-pattern>/randomcode.jpg</url-pattern> </servlet-mapping>四、由于需要kaptcha-2.3.jar包，所以将下载好的jar包导入在lib中。（复制黏贴即可）
其他：
一、网页验证码的属性
（一）添加边框
<servlet> <init-param> <description>图片边框，合法值：yes , no</description> <param-name>kaptcha.border</param-name> <param-value>yes</param-value> <!-- yes 或者 no--> </init-param> </servlet>（二）边框颜色
<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>（三）边框厚度
<init-param> <description>边框厚度，合法值：>大于0 </description> <param-name>kaptcha.border.thickness</param-name> <param-value>1</param-value> </init-param>（四）图片宽度
<init-param> <description>图片宽 200</description> <param-name>kaptcha.image.width</param-name> <param-value>200</param-value> </init-param>（五）图片高度
<init-param> <description>图片高 50</description> <param-name>kaptcha.image.height</param-name> <param-value>50</param-value> </init-param>（六）验证码集合
<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> <!--纯数字 --> //<param-value>abcde2345678gfynmnpwx</param-value> <!-- 文字加英文--> </init-param>（七）验证码长度
<init-param> <description>验证码长度 默认是5 </description> <param-name>kaptcha.textproducer.char.length</param-name> <param-value>2</param-value> </init-param>（八）字体
<init-param> <description>字体 Arial, Courier</description> <param-name>kaptcha.textproducer.font.names</param-name> <param-value>Arial, Courier</param-value> </init-param>（九）字体大小
<init-param> <description>字体大小 40px.</description> <param-name>kaptcha.textproducer.font.size</param-name> <param-value>40</param-value> </init-param>（十）字体颜色
<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>（十一）每个验证码之间的间隔
<init-param> <description>文字间隔 2</description> <param-name>kaptcha.textproducer.char.space</param-name> <param-value>2</param-value> </init-param>（十二）干扰实现
<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>（十三）干扰颜色
<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>（十四）背景样式
<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>（十五）背景实现类
<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>（十六）背景渐变颜色
<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>（十七）文字渲染器
<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>（十八）图片的验证码会保存在Session中，其中的值为
<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>（十九）图片实现类别
<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>（二十）文本实现类（可通过重写该类来实现验证码为中文）
<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>重写文本实现类，实现验证码为中文：
1.创建一个类别，继承Configurable 实现TextProducer（在jar包中）
import com.google.code.kaptcha.text.TextProducer; import com.google.code.kaptcha.util.Configurable; import java.util.Random; public class ChineseText extends Configurable implements TextProducer { public String getText() { int length = getConfig().getTextProducerCharLength(); String finalWord = "", firstWord = ""; int tempInt = 0; String[] array = { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" }; Random rand = new Random(); for (int i = 0; i < length; i++) { switch (rand.nextInt(array.length)) { case 1: tempInt = rand.nextInt(26) + 65; firstWord = String.valueOf((char) tempInt); break; case 2: int r1, r2, r3, r4; String strH, strL;// high&low r1 = rand.nextInt(3) + 11; // 前闭后开[11,14) if (r1 == 13) { r2 = rand.nextInt(7); } else { r2 = rand.nextInt(16); } r3 = rand.nextInt(6) + 10; if (r3 == 10) { r4 = rand.nextInt(15) + 1; } else if (r3 == 15) { r4 = rand.nextInt(15); } else { r4 = rand.nextInt(16); } strH = array[r1] + array[r2]; strL = array[r3] + array[r4]; byte[] bytes = new byte[2]; bytes[0] = (byte) (Integer.parseInt(strH, 16)); bytes[1] = (byte) (Integer.parseInt(strL, 16)); firstWord = new String(bytes); break; default: tempInt = rand.nextInt(10) + 48; firstWord = String.valueOf((char) tempInt); break; } finalWord += firstWord; } return finalWord; } }2.修改Web.xml配置
<init-param> <description>文本实现类</description> <param-name>kaptcha.textproducer.impl</param-name> <param-value> ChineseText </param-value> </init-param> 五、验证码的校验（本文是利用check.jsp来校验的）保存在Session中，其中的键值为（第十八个属性） [html] view plain copy <body> <% // 检查是否是正确的验证码 String k = (String) session.getAttribute(com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY); String str = request.getParameter("r"); if (k.equals(str)) out.print("true"); out.print(k + "---" + str); %> </body>六、扩展（加法验证码的实现）
1.重写KaptchaServlet类
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; import javax.servlet.http.HttpSession; 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/jpg"); 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(); } } }2.修改配置文件
<servlet> <servlet-name>Kaptcha</servlet-name> <servlet-class>KaptchaServlet</servlet-class> </servlet>以上所述是小编给大家介绍的使用开源工具制作网页验证码的方法，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对网站的支持！
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