jcaptcha

最近学习了一下验证码实现，学习了一下jcaptcha开源验证技术，网上搜索了一下资料，学习整理了一下
1.需要的JAR
  commons-collections-3.1.jar,commons-collections-3.1.jar
Java代码
package com.code;  
 
import com.octo.captcha.service.image.DefaultManageableImageCaptchaService;  
import com.octo.captcha.service.image.ImageCaptchaService;  
 
/***********************************************************************    
*    
*   CaptchaServiceSingleton.java      
*   @copyright       Copyright:   2009-2012      
*   @creator         周辉<br/>    
*   @create-time   Jun 18, 2009   1:31:44 PM    
*   @revision         $Id:     *    
***********************************************************************/ 
public class CaptchaServiceSingleton {  
    private static ImageCaptchaService instance = new DefaultManageableImageCaptchaService();     
      
    public static ImageCaptchaService getInstance(){     
        return instance;     
    }     
} 

编写一个产生图片的servlet
Java代码
package com.code;  
 
import java.awt.image.BufferedImage;  
import java.io.ByteArrayOutputStream;  
import java.io.IOException;  
 
import javax.servlet.ServletConfig;  
import javax.servlet.ServletException;  
import javax.servlet.ServletOutputStream;  
import javax.servlet.http.HttpServlet;  
import javax.servlet.http.HttpServletRequest;  
import javax.servlet.http.HttpServletResponse;  
 
import com.octo.captcha.service.CaptchaServiceException;  
import com.sun.image.codec.jpeg.JPEGCodec;  
import com.sun.image.codec.jpeg.JPEGImageEncoder;  
 
/***********************************************************************    
*    
*   ImageCaptchaServlet.java      
*   @copyright       Copyright:   2009-2012      
*   @creator         周辉<br/>    
*   @create-time   Jun 18, 2009   1:32:50 PM    
*   @revision         $Id:     *    
***********************************************************************/ 
public class ImageCaptchaServlet extends HttpServlet {  
    public void init(ServletConfig servletConfig) throws ServletException {     
            
        super.init(servletConfig);     
    
    }     
    
    
    protected void doGet(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) throws ServletException, IOException {     
             
       byte[] captchaChallengeAsJpeg = null;     
       // the output stream to render the captcha image as jpeg into     
        ByteArrayOutputStream jpegOutputStream = new ByteArrayOutputStream();     
        try {     
        // get the session id that will identify the generated captcha.      
        //the same id must be used to validate the response, the session id is a good candidate!     
        String captchaId = httpServletRequest.getSession().getId();     
        // call the ImageCaptchaService getChallenge method     
            BufferedImage challenge =     
                    CaptchaServiceSingleton.getInstance().getImageChallengeForID(captchaId,     
                            httpServletRequest.getLocale());     
                 
            // a jpeg encoder     
            JPEGImageEncoder jpegEncoder =     
                    JPEGCodec.createJPEGEncoder(jpegOutputStream);     
            jpegEncoder.encode(challenge);     
        } catch (IllegalArgumentException e) {     
            httpServletResponse.sendError(HttpServletResponse.SC_NOT_FOUND);     
            return;     
        } catch (CaptchaServiceException e) {     
            httpServletResponse.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);     
            return;     
        }     
    
        captchaChallengeAsJpeg = jpegOutputStream.toByteArray();     
    
        // flush it in the response     
        httpServletResponse.setHeader("Cache-Control", "no-store");     
        httpServletResponse.setHeader("Pragma", "no-cache");     
        httpServletResponse.setDateHeader("Expires", 0);     
        httpServletResponse.setContentType("image/jpeg");     
        ServletOutputStream responseOutputStream =     
                httpServletResponse.getOutputStream();     
        responseOutputStream.write(captchaChallengeAsJpeg);     
        responseOutputStream.flush();     
        responseOutputStream.close();     
    }    
} 
为servlet修改web.xml配置文件
Xml代码
<servlet>    
        <servlet-name>jcaptcha</servlet-name>    
        <servlet-class>com.code.ImageCaptchaServlet</servlet-class>    
        <load-on-startup>0</load-on-startup>    
    </servlet>    
    <servlet-mapping>    
        <servlet-name>jcaptcha</servlet-name>    
        <url-pattern>/jcaptcha</url-pattern>    
    </servlet-mapping>    
      
    <servlet>    
        <servlet-name>checkjcaptcha</servlet-name>    
        <servlet-class>com.code.ValidationServlet</servlet-class>    
        <load-on-startup>1</load-on-startup>    
    </servlet>    
    <servlet-mapping>    
        <servlet-name>checkjcaptcha</servlet-name>    
        <url-pattern>/validateAction</url-pattern>    
    </servlet-mapping> 
其中jcaptcha 是生成图片的Servlet
checkjcaptcha是验证用的Servlet
编写你的客户端的展示
login.html
Html代码
<html>    
  <head>    
    <title>MyHtml.html</title>    
         
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">    
    <meta http-equiv="description" content="this is my page">    
    <meta http-equiv="content-type" content="text/html; charset=UTF-8">    
         
    <!--<link rel="stylesheet" type="text/css" href="./styles.css">-->    
    
  </head>    
       
  <body>    
    <form name="f1" id="f1" action="/jcaptcha/validateAction" method="get">    
      <table border="0">    
        <tr>    
          <td>验证码:</td>    
          <td><img src="jcaptcha"><input type='text' name='j_captcha_response' value=''></td>    
        </tr>    
        <tr>    
          <td colspan="2" align="center"><input type="submit"></td>    
        </tr>    
      </table>    
           
    </form>    
  </body>    
</html>   
2 个检验成功失败的页面success.html ,failture.html 这2个页面超级简单这里略

后台逻辑验证
Java代码
package com.code;  
 
import java.io.IOException;  
 
import javax.servlet.ServletConfig;  
import javax.servlet.ServletException;  
import javax.servlet.http.HttpServlet;  
import javax.servlet.http.HttpServletRequest;  
import javax.servlet.http.HttpServletResponse;  
 
import com.octo.captcha.service.CaptchaServiceException;  
 
/***********************************************************************    
*    
*   ValidationServlet.java      
*   @copyright       Copyright:   2009-2012      
*   @creator         周辉<br/>    
*   @create-time   Jun 18, 2009   1:36:02 PM    
*   @revision         $Id:     *    
***********************************************************************/ 
public class ValidationServlet extends HttpServlet {  
    public void init(ServletConfig servletConfig) throws ServletException {     
            
        super.init(servletConfig);     
    
    }     
    
    protected void doGet(HttpServletRequest httpServletRequest,     
            HttpServletResponse httpServletResponse) throws ServletException,     
            IOException {     
    
        Boolean isResponseCorrect = Boolean.FALSE;     
        //remenber that we need an id to validate!     
        String captchaId = httpServletRequest.getSession().getId();     
        //retrieve the response     
        String response = httpServletRequest.getParameter("j_captcha_response");     
        // Call the Service method     
        try {     
            isResponseCorrect = CaptchaServiceSingleton.getInstance()     
                    .validateResponseForID(captchaId, response);   
        } catch (CaptchaServiceException e) {     
            //should not happen, may be thrown if the id is not valid      
        }     
        System.out.println(isResponseCorrect);   
       // httpServletResponse.encodeUrl("sucess.html");  
        if(isResponseCorrect.booleanValue()){  
            httpServletResponse.sendRedirect("success.html");  
        }  
        else {  
             httpServletResponse.sendRedirect("failture.html");  
        }  
    }     
} 

最后发布程序 启动TOMCAT
ps:需要注意的是 ImageCaptchaService 在使用时应该是单例的