001/* 002 * Shredzone Commons 003 * 004 * Copyright (C) 2012 Richard "Shred" Körber 005 * http://commons.shredzone.org 006 * 007 * This program is free software: you can redistribute it and/or modify 008 * it under the terms of the GNU Library General Public License as 009 * published by the Free Software Foundation, either version 3 of the 010 * License, or (at your option) any later version. 011 * 012 * This program is distributed in the hope that it will be useful, 013 * but WITHOUT ANY WARRANTY; without even the implied warranty of 014 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 015 * GNU General Public License for more details. 016 * 017 * You should have received a copy of the GNU Library General Public License 018 * along with this program. If not, see <http://www.gnu.org/licenses/>. 019 */ 020package org.shredzone.commons.captcha; 021 022import java.awt.image.BufferedImage; 023 024import javax.imageio.ImageIO; 025import javax.servlet.http.HttpServletRequest; 026import javax.servlet.http.HttpServletResponse; 027 028import org.springframework.web.servlet.FrameworkServlet; 029 030/** 031 * This servlet creates a random captcha image, stores the correct answer in the http 032 * session, and streams the generated captcha image as PNG. 033 * 034 * @author Richard "Shred" Körber 035 */ 036public class CaptchaServlet extends FrameworkServlet { 037 private static final long serialVersionUID = 3241024444677649962L; 038 039 @Override 040 protected void doService(HttpServletRequest request, HttpServletResponse response) 041 throws Exception { 042 if (!request.getMethod().equals("GET")) { 043 response.sendError(HttpServletResponse.SC_NOT_IMPLEMENTED, 044 request.getMethod() + " is not accepted"); 045 } 046 047 // Prepare header 048 response.setDateHeader("Date", System.currentTimeMillis()); 049 response.setHeader("Cache-Control", "no-store"); 050 response.setHeader("Pragma", "no-cache"); 051 response.setDateHeader("Expires", 0); 052 response.setContentType("image/png"); 053 054 // Write captcha image 055 CaptchaService cs = getWebApplicationContext().getBean("captchaService", CaptchaService.class); 056 BufferedImage challenge = cs.createCaptcha(request.getSession()); 057 ImageIO.write(challenge, "png", response.getOutputStream()); 058 } 059 060}