google 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

<!--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>

      <servlet-mapping>
        <servlet-name>kaptcha</servlet-name>
        <url-pattern>/ClinicCountManager/kaptcha.jpg</url-pattern>
    </servlet-mapping>

JSP页面：

    <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：

<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：

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：

 <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：

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

如果需要纯数字：

        <init-param>
            <param-name>kaptcha.textproducer.char.string</param-name>
            <param-value>0123456789</param-value>
        </init-param>

去掉干扰线：

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

转载自：http://stone02111.iteye.com/blog/1688195