imagecode.java

一个留言板 系统平台： JSP+SQLServer 支持开通无限个数的留言板

/*
 * ImageCode.java
 *
 * Created on 2006年7月25日, 下午6:05
 *
 * To change this template, choose Tools | Options and locate the template under
 * the Source Creation and Management node. Right-click the template and choose
 * Open. You can then make changes to the template in the Source Editor.
 */

package tot.image;
import java.io.*;
import java.net.*;
import java.awt.image.BufferedImage;

import javax.servlet.*;
import javax.servlet.http.*;

import com.octo.captcha.service.CaptchaServiceException;
import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;
/**
 *
 * @author Administrator
 * @version
 */
public class ImageCode extends HttpServlet {
    public void init(ServletConfig servletConfig) throws ServletException {
        
        super.init(servletConfig);
        
    }
    
    /** Processes requests for both HTTP <code>GET</code> and <code>POST</code> methods.
     * @param request servlet request
     * @param response servlet response
     */
    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
    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 = request.getSession().getId();
            // call the ImageCaptchaService getChallenge method
            BufferedImage challenge =CaptchaServiceSingleton.getInstance().getImageChallengeForID(captchaId,request.getLocale());
            
            // a jpeg encoder
            JPEGImageEncoder jpegEncoder=JPEGCodec.createJPEGEncoder(jpegOutputStream);
            jpegEncoder.encode(challenge);
        } catch (IllegalArgumentException e) {
            response.sendError(response.SC_NOT_FOUND);
            return;
        } catch (CaptchaServiceException e) {
            response.sendError(response.SC_INTERNAL_SERVER_ERROR);
            return;
        }        
        captchaChallengeAsJpeg = jpegOutputStream.toByteArray();        
        // flush it in the response
        response.setHeader("Cache-Control", "no-store");
        response.setHeader("Pragma", "no-cache");
        response.setDateHeader("Expires", 0);
        response.setContentType("image/jpeg");
        ServletOutputStream responseOutputStream =response.getOutputStream();
        responseOutputStream.write(captchaChallengeAsJpeg);
        responseOutputStream.flush();
        responseOutputStream.close();
    }
    
// <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
    /** Handles the HTTP <code>GET</code> method.
     * @param request servlet request
     * @param response servlet response
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
        processRequest(request, response);
    }
    
    /** Handles the HTTP <code>POST</code> method.
     * @param request servlet request
     * @param response servlet response
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
        processRequest(request, response);
    }
    
    /** Returns a short description of the servlet.
     */
    public String getServletInfo() {
        return "Short description";
    }
// </editor-fold>
}