kaptcha 简单方便的验证码生成工具

Posted by 李小武 on September 11, 2010

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。

kaptcha可以配置一下信息:

1.验证码的字体
2.验证码字体的大小
3.验证码字体的字体颜色
4.验证码内容的范围(数字,字母,中文汉字!)
5.验证码图片的大小,边框,边框粗细,边框颜色
6.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)
7.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)
8.……

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

其实就是配置com.google.code.kaptcha.servlet.KaptchaServlet

<?xml version="1.0" encoding="UTF-8"?>
<web-app 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"
         version="2.4">
    <servlet>
        <servlet-name>Kaptcha</servlet-name>
        <servlet-class>com.google.code.kaptcha.servlet.KaptchaServlet</servlet-class>
        <init-param>
            <description>Border around kaptcha. Legal values are yes or no.</description>
            <param-name>kaptcha.border</param-name>
            <param-value>no</param-value>
        </init-param>
        <init-param>
            <description>Color of the border. Legal values are r,g,b (and
                optional alpha) or white,black,blue.
            </description>
            <param-name>kaptcha.border.color</param-name>
            <param-value>red</param-value>
        </init-param>
        <init-param>
            <description>Thickness of the border around kaptcha. Legal values are
                > 0.
            </description>
            <param-name>kaptcha.border.thickness</param-name>
            <param-value>5</param-value>
        </init-param>
        <init-param>
            <description>Width in pixels of the kaptcha image.</description>
            <param-name>kaptcha.image.width</param-name>
            <param-value>80</param-value>
        </init-param>
        <init-param>
            <description>Height in pixels of the kaptcha image.</description>
            <param-name>kaptcha.image.height</param-name>
            <param-value>40</param-value>
        </init-param>
        <init-param>
            <description>The image producer.</description>
            <param-name>kaptcha.producer.impl</param-name>
            <param-value>com.google.code.kaptcha.impl.DefaultKaptcha</param-value>
        </init-param>
        <init-param>
            <description>The text producer.</description>
            <param-name>kaptcha.textproducer.impl</param-name>
            <param-value>com.google.code.kaptcha.text.impl.DefaultTextCreator</param-value>
        </init-param>
        <init-param>
            <description>The characters that will create the kaptcha.</description>
            <param-name>kaptcha.textproducer.char.string</param-name>
            <param-value>abcde2345678gfynmnpwx</param-value>
        </init-param>
        <init-param>
            <description>The number of characters to display.</description>
            <param-name>kaptcha.textproducer.char.length</param-name>
            <param-value>5</param-value>
        </init-param>
        <init-param>
            <description>A list of comma separated font names.</description>
            <param-name>kaptcha.textproducer.font.names</param-name>
            <param-value>Arial, Courier</param-value>
        </init-param>
        <init-param>
            <description>The size of the font to use.</description>
            <param-name>kaptcha.textproducer.font.size</param-name>
            <param-value>23</param-value>
        </init-param>
        <init-param>
            <description>The color to use for the font. Legal values are r,g,b.</description>
            <param-name>kaptcha.textproducer.font.color</param-name>
            <param-value>black</param-value>
        </init-param>
        <init-param>
            <description>The noise producer.</description>
            <param-name>kaptcha.noise.impl</param-name>
            <param-value>com.google.code.kaptcha.impl.NoNoise</param-value>
        </init-param>
        <init-param>
            <description>The noise color. Legal values are r,g,b.</description>
            <param-name>kaptcha.noise.color</param-name>
            <param-value>black</param-value>
        </init-param>
        <init-param>
            <description>The obscurificator implementation.</description>
            <param-name>kaptcha.obscurificator.impl</param-name>
            <param-value>com.google.code.kaptcha.impl.ShadowGimpy</param-value>
        </init-param>
        <init-param>
            <description>The background implementation.</description>
            <param-name>kaptcha.background.impl</param-name>
            <param-value>com.google.code.kaptcha.impl.DefaultBackground</param-value>
        </init-param>
        <init-param>
            <description>Ending background color. Legal values are r,g,b.</description>
            <param-name>kaptcha.background.clear.to</param-name>
            <param-value>white</param-value>
        </init-param>
        <init-param>
            <description>The word renderer implementation.</description>
            <param-name>kaptcha.word.impl</param-name>
            <param-value>com.google.code.kaptcha.text.impl.DefaultWordRenderer</param-value>
        </init-param>
        <init-param>
            <description>The value for the kaptcha is generated and is put into
                the HttpSession. This is the key value for that item in the session.
            </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 the
                HttpSession. This is the key value for that item in the session.
            </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>/Kaptcha.jpg</url-pattern>
    </servlet-mapping>
    <welcome-file-list>
        <welcome-file>KaptchaExample.jsp</welcome-file>
    </welcome-file-list>
</web-app>   

编写KaptchaExample.jsp 这里用到了jQuery,所以添加了jQuery的库

<img src="Kaptcha.jpg" mce_src="Kaptcha.jpg" id="kaptchaImage"/>
<script type="text/javascript">
    $('#kaptchaImage').click(
        function () {
            $(this).hide().attr('src','Kaptcha.jpg?' + Math.floor(Math.random() **100)).fadeIn();
    })
</script>
<%
    String c = (String) session
            .getAttribute(com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY);
    String parm = (String) request.getParameter("kaptchafield");

    System.out.println(c);
    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>");
        }
    }
%>

运行测试

工程下载:http://download.csdn.net/source/2687960