Java tutorial
/* * Weblounge: Web Content Management System * Copyright (c) 2012 The Weblounge Team * http://weblounge.o2it.ch * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public License * as published by the Free Software Foundation; either version 2 * of the License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public License * along with this program; if not, write to the Free Software Foundation * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ package ch.entwine.weblounge.dispatcher.impl.handler; import ch.entwine.weblounge.common.request.WebloungeRequest; import ch.entwine.weblounge.common.request.WebloungeResponse; import ch.entwine.weblounge.common.site.Environment; import ch.entwine.weblounge.common.url.WebUrl; import ch.entwine.weblounge.dispatcher.RequestHandler; import ch.entwine.weblounge.dispatcher.impl.DispatchUtils; import org.apache.commons.io.IOUtils; import org.osgi.framework.BundleContext; import org.osgi.service.component.ComponentContext; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.io.IOException; import java.io.InputStream; import java.util.Date; import javax.servlet.http.HttpServletResponse; /** * This request handler deals with requests to <code>/robots.txt</code> if the * target site does not ship its own. */ public class RobotsRequestHandlerImpl implements RequestHandler { /** Logging facility */ private static final Logger logger = LoggerFactory.getLogger(RobotsRequestHandlerImpl.class); /** Request uri */ public static final String URI_PREFIX = "/robots.txt"; /** Path to restrictive robots txt */ public static final String ROBOTS_DISALLOW_TXT = "/robots/robots-disallow.txt"; /** Path to default robots txt */ public static final String ROBOTS_ALLOW_TXT = "/robots/robots-allow.txt"; /** Content of the default robots.txt */ private String allowRobotsTxt = null; /** Content of the restrictive robots.txt */ private String disallowRobotsTxt = null; /** The bundle's modification date */ private Date modificationDate = new Date(); /** * Creates a new robots.txt request handler. * * @throws IOException * if the robots.txt files could not be loaded from the bundle * resource */ public RobotsRequestHandlerImpl() throws IOException { InputStream is = null; // Read permissive robots.txt try { is = RobotsRequestHandlerImpl.class.getResourceAsStream(ROBOTS_ALLOW_TXT); allowRobotsTxt = IOUtils.toString(is); } catch (IOException e) { logger.error("Error loading {} from bundle", ROBOTS_ALLOW_TXT); } finally { IOUtils.closeQuietly(is); } // Read restrictive robots.txt try { is = RobotsRequestHandlerImpl.class.getResourceAsStream(ROBOTS_DISALLOW_TXT); disallowRobotsTxt = IOUtils.toString(is); } catch (IOException e) { logger.error("Error loading {} from bundle", ROBOTS_DISALLOW_TXT); } finally { IOUtils.closeQuietly(is); } } /** * OSGi callback upon component activation that provides access to the * component and bundle context. * * @param ctx * the context */ void activate(ComponentContext ctx) { BundleContext bundleCtx = ctx.getBundleContext(); modificationDate = new Date(bundleCtx.getBundle().getLastModified()); } /** * {@inheritDoc} * * @see ch.entwine.weblounge.dispatcher.RequestHandler#service(ch.entwine.weblounge.common.request.WebloungeRequest, * ch.entwine.weblounge.common.request.WebloungeResponse) */ public boolean service(WebloungeRequest request, WebloungeResponse response) { WebUrl url = request.getUrl(); String path = url.getPath(); // Is the request intended for this handler? if (!URI_PREFIX.equals(path)) { logger.debug("Skipping request for {}, request path does not start with {}", URI_PREFIX); return false; } // Check the request method. Only GET is supported right now. String requestMethod = request.getMethod().toUpperCase(); if ("OPTIONS".equals(requestMethod)) { String verbs = "OPTIONS,GET"; logger.trace("Answering options request to {} with {}", url, verbs); response.setHeader("Allow", verbs); response.setContentLength(0); return true; } else if (!"GET".equals(requestMethod)) { logger.debug("Robots request handler does not support {} requests", requestMethod); DispatchUtils.sendError(HttpServletResponse.SC_METHOD_NOT_ALLOWED, request, response); return true; } // Decide on which directives to send String robotsDirective = null; if (Environment.Production.equals(request.getEnvironment())) { // TODO: Get hold of the site bundle and check for an existing robots.txt robotsDirective = allowRobotsTxt; } else { robotsDirective = disallowRobotsTxt; } // Send the response try { response.setContentType("text/plain"); response.setContentLength(robotsDirective.length()); response.setModificationDate(modificationDate); IOUtils.write(robotsDirective, response.getOutputStream(), "UTF-8"); } catch (IOException e) { logger.warn("Error sending robots.txt to client: {}", e.getMessage()); } return true; } /** * {@inheritDoc} * * @see ch.entwine.weblounge.dispatcher.RequestHandler#getPriority() */ public int getPriority() { return 0; } /** * {@inheritDoc} * * @see ch.entwine.weblounge.dispatcher.RequestHandler#getName() */ public String getName() { return "robots.txt request handler"; } /** * {@inheritDoc} * * @see java.lang.Object#toString() */ @Override public String toString() { return getName(); } }