kaptcha验证码组件使用简介解析

<!-- kaptcha --> <dependency>   <groupId>com.google.code.kaptcha</groupId>   <artifactId>kaptcha</artifactId>   <version>2.3.2</version> </dependency> 

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

<servlet>   <servlet-name>Kaptcha</servlet-name>   <servlet-class>com.google.code.kaptcha.servlet.KaptchaServlet</servlet-class>   <init-param>     <param-name>kaptcha.image.width</param-name>     <param-value>200</param-value>     <description>Width in pixels of the kaptcha image.</description>   </init-param>   <init-param>     <param-name>kaptcha.image.height</param-name>     <param-value>50</param-value>     <description>Height in pixels of the kaptcha image.</description>   </init-param>   <init-param>     <param-name>kaptcha.textproducer.char.length</param-name>     <param-value>4</param-value>     <description>The number of characters to display.</description>   </init-param>   <init-param>     <param-name>kaptcha.noise.impl</param-name>     <param-value>com.google.code.kaptcha.impl.NoNoise</param-value>     <description>The noise producer.</description>   </init-param> </servlet> 

<form action="submit.action">   <input type="text" name="kaptcha" value="" /><img src="kaptcha.jpg" /> </form> 

//从session中取出servlet生成的验证码text值 String kaptchaExpected = (String)request.getSession().getAttribute(com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY); //获取用户页面输入的验证码 String kaptchaReceived = request.getParameter("kaptcha"); //校验验证码是否正确 if (kaptchaReceived == null || !kaptchaReceived.equalsIgnoreCase(kaptchaExpected)){   setError("kaptcha", "Invalid validation code."); } 

<img src="kaptcha.jpg" width="200" id="kaptchaImage" title="看不清，点击换一张" /> <script type="text/javascript">   $(function() {     $('#kaptchaImage').click(function() {$(this).attr('src','kaptcha.jpg?' + Math.floor(Math.random() * 100));});   }); </script> <br /><small>看不清，点击换一张</small> 

<!-- 配置kaptcha验证码 --> <bean id="captchaProducer" class="com.google.code.kaptcha.impl.DefaultKaptcha">   <property name="config">     <bean class="com.google.code.kaptcha.util.Config">       <constructor-arg type="java.util.Properties">         <props>           <prop key="kaptcha.image.width">100</prop>           <prop key="kaptcha.image.height">50</prop>           <prop key="kaptcha.noise.impl">com.google.code.kaptcha.impl.NoNoise</prop>           <prop key="kaptcha.textproducer.char.string">0123456789abcdefghijklmnopqrstuvwxyz</prop>           <prop key="kaptcha.textproducer.char.length">4</prop>         </props>       </constructor-arg>     </bean>   </property> </bean> 

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;  /**  * ClassName: CaptchaImageCreateController <br/>  * Function: 生成验证码Controller. <br/>  * date: 2013-12-10 上午11:37:42 <br/>  *  * @author chenzhou1025@126.com  */ @Controller public class CaptchaImageCreateController {   private Producer captchaProducer = null;    @Autowired   public void setCaptchaProducer(Producer captchaProducer){     this.captchaProducer = captchaProducer;   }    @RequestMapping("/kaptcha.jpg")   public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception{     // Set to expire far in the past.     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;   } } 

/** * ClassName: LoginController <br/> * Function: 登录Controller. <br/> * date: 2013-12-10 上午11:41:43 <br/> * * @author chenzhou1025@126.com */@Controller@RequestMapping("/login")public class LoginController {	/**	 * loginCheck:ajax异步校验登录请求. <br/>	 *	 * @author chenzhou1025@126.com	 * @param request	 * @param username 用户名	 * @param password 密码	 * @param kaptchaReceived 验证码	 * @return 校验结果	 * @since 2013-12-10	 */	@RequestMapping(value = "check", method = RequestMethod.POST)	@ResponseBody	public String loginCheck(HttpServletRequest request,			@RequestParam(value = "username", required = true) String username,			@RequestParam(value = "password", required = true) String password,			@RequestParam(value = "kaptcha", required = true) String kaptchaReceived){		//用户输入的验证码的值		String kaptchaExpected = (String) request.getSession().getAttribute(				com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY);		//校验验证码是否正确		if (kaptchaReceived == null || !kaptchaReceived.equals(kaptchaExpected)) {			return "kaptcha_error";//返回验证码错误		}		//校验用户名密码		// ……		// ……		return "success"; //校验通过返回成功	}}