jcaptcha（转）

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Servlet Java Tomcat HTML SUN

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">

    

</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

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