kaptcha 验证码组件使用简介

kaptcha 是一个非常实用的验证码生成工具。有了它，你可以生成各种样式的验证码，因为它是可配置的。kaptcha工作的原理是调用 com.google.code.kaptcha.servlet.KaptchaServlet，生成一个图片。同时将生成的验证码字符串放到 HttpSession中。

使用kaptcha可以方便的配置：

验证码的字体
验证码字体的大小
验证码字体的字体颜色
验证码内容的范围(数字，字母，中文汉字！)
验证码图片的大小，边框，边框粗细，边框颜色
验证码的干扰线(可以自己继承com.google.code.kaptcha.NoiseProducer写一个自定义的干扰线)
验证码的样式(鱼眼样式、3D、普通模糊……当然也可以继承com.google.code.kaptcha.GimpyEngine自定义样式)

……

详细信息请看下面的web.xml文件

下面介绍一下用法:

1.首先去官网下载jar:http://code.google.com/p/kaptcha/

2.建立一个web项目，导入kaptcha-2.3.jar到环境变量中。

3.配置web.xml文件

Java代码


<!--Kaptcha 验证码 --><!--

<servlet>

<servlet-name>kaptcha</servlet-name>

<servlet-class>com.google.code.kaptcha.servlet.KaptchaServlet</servlet-class>

<init-param>

<param-name>kaptcha.border</param-name>

<param-value>no</param-value>

</init-param>

<init-param>

<param-name>kaptcha.border.color</param-name>

<param-value>105,179,90</param-value>

</init-param>

<init-param>

<param-name>kaptcha.textproducer.font.color</param-name>

<param-value>red</param-value>

</init-param>

<init-param>

<param-name>kaptcha.image.width</param-name>

<param-value>250</param-value>

</init-param>

<init-param>

<param-name>kaptcha.image.height</param-name>

<param-value>90</param-value>

</init-param>

<init-param>

<param-name>kaptcha.textproducer.font.size</param-name>

<param-value>70</param-value>

</init-param>

<init-param>

<param-name>kaptcha.session.key</param-name>

<param-value>code</param-value>

</init-param>

<init-param>

<param-name>kaptcha.textproducer.char.length</param-name>

<param-value>4</param-value>

</init-param>

<init-param>

<param-name>kaptcha.textproducer.font.names</param-name>

<param-value>宋体,楷体,微软雅黑</param-value>

</init-param>

</servlet>

Java代码


<servlet-mapping>

<servlet-name>kaptcha</servlet-name>

<url-pattern>/ClinicCountManager/kaptcha.jpg</url-pattern>

lt;/servlet-mapping>

jsp 页面使用

Java代码


<table>

<tr>

<td><img src="/ClinicCountManager/kaptcha.jpg"></td>

<td valign="top">

<form method="POST">

<br>sec code:<input type="text" name="kaptchafield"><br />

<input type="submit" name="submit">

</form>

</td>

</tr>

</table>

<br /><br /><br /><br />

<%

String c = (String)session.getAttribute(com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY);

String parm = (String) request.getParameter("kaptchafield");

out.println("Parameter: " + parm + " ? Session Key: " + c + " : ");

if (c != null && parm != null) {

if (c.equals(parm)) {

out.println("<b>true</b>");

} else {

out.println("<b>false</b>");

}

%>

上面的配置在普通jsp环境下面是有效的，如果在spring mvc环境下，则取不到session值，对于sping mvc环境验证码配置如下：

１.不用在web.xml进行相关配置，在applicationContext.xml中配置

Java代码


<bean id="captchaProducer" class="com.google.code.kaptcha.impl.DefaultKaptcha">

<property name="config">

<bean class="com.google.code.kaptcha.util.Config">

<constructor-arg>

<props>

<prop key="kaptcha.border">no</prop>

<prop key="kaptcha.border.color">105,179,90</prop>

<prop key="kaptcha.textproducer.font.color">red</prop>

<prop key="kaptcha.image.width">250</prop>

<prop key="kaptcha.textproducer.font.size">90</prop>

<prop key="kaptcha.image.height">90</prop>

<prop key="kaptcha.session.key">code</prop>

<prop key="kaptcha.textproducer.char.length">4</prop>

<prop key="kaptcha.textproducer.font.names">宋体,楷体,微软雅黑</prop>

</props>

</constructor-arg>

</bean>

</property>

</bean>

新建生成图片控制类

Java代码


import java.awt.image.BufferedImage;

import javax.imageio.ImageIO;

import javax.servlet.ServletOutputStream;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.stereotype.Controller;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.servlet.ModelAndView;

import com.google.code.kaptcha.Constants;

import com.google.code.kaptcha.Producer;

@Controller

@RequestMapping("/")

public class CaptchaImageCreateController {

private Producer captchaProducer = null;

@Autowired

public void setCaptchaProducer(Producer captchaProducer) {

this.captchaProducer = captchaProducer;

}

@RequestMapping("/captcha-image")

public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception {

response.setDateHeader("Expires", 0);

// Set standard HTTP/1.1 no-cache headers.

response.setHeader("Cache-Control", "no-store, no-cache, must-revalidate");

// Set IE extended HTTP/1.1 no-cache headers (use addHeader).

response.addHeader("Cache-Control", "post-check=0, pre-check=0");

// Set standard HTTP/1.0 no-cache header.

response.setHeader("Pragma", "no-cache");

// return a jpeg

response.setContentType("image/jpeg");

// create the text for the image

String capText = captchaProducer.createText();

// store the text in the session

request.getSession().setAttribute(Constants.KAPTCHA_SESSION_KEY, capText);

// create the image with the text

BufferedImage bi = captchaProducer.createImage(capText);

ServletOutputStream out = response.getOutputStream();

// write the data out

ImageIO.write(bi, "jpg", out);

try {

out.flush();

} finally {

out.close();

}

return null;

}

}

前台调用方式

Java代码


<div class="chknumber">

<label>验证码：

<input name="kaptcha" type="text" id="kaptcha" maxlength="4" class="chknumber_input" />

</label>

<img src="/ClinicCountManager/captcha-image.do" width="55" height="20" id="kaptchaImage" style="margin-bottom: -3px"/>

<script type="text/javascript">

$(function(){

$('#kaptchaImage').click(function () {//生成验证码

$(this).hide().attr('src', '/ClinicCountManager/captcha-image.do?' + Math.floor(Math.random()*100) ).fadeIn(); })

});

</script>

</div>

取验证码的方式

Java代码


String code = (String)session.getAttribute(com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY);

如果需要全部数字

Java代码


<init-param>

<param-name>kaptcha.textproducer.char.string</param-name>

<param-value>0123456789</param-value>

</init-param>

去掉干扰线

Java代码


<init-param>

<param-name>kaptcha.noise.impl</param-name>

<param-value>com.google.code.kaptcha.impl.NoNoise </param-value>

</init-param>