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/
POM文件：
<!-- 中央仓库没得，必须去https://repository.sonatype.org私服拉取--> <dependency> <groupId>com.google.code.kaptcha</groupId> <artifactId>kaptcha</artifactId> <version>2.3</version> <classifier>jdk15</classifier> </dependency>
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
