使用开源工具制作网页验证码的方法
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 alt="random" 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/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();
}
}
}
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来客网网站的支持！
