jcaptcha学习

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

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

<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>  
  <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

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
运行http://localhost:8081/jcaptcha/login.html运行看到了吧(我的TOMCAT 端口是8081，默认是8080)