AbstractServlet.java

/*
 * Copyright (c) 2006-2009 by Dirk Riehle, http://dirkriehle.com
 *
 * This file is part of the Wahlzeit photo rating application.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public
 * License along with this program. If not, see
 * <http://www.gnu.org/licenses/>.
 */

package org.wahlzeit.servlets;

import org.wahlzeit.main.ServiceMain;
import org.wahlzeit.model.UserSession;
import org.wahlzeit.services.LogBuilder;
import org.wahlzeit.services.Session;
import org.wahlzeit.services.SessionManager;
import org.wahlzeit.utils.StringUtil;
import org.wahlzeit.webparts.WebPart;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.util.Iterator;
import java.util.Map;
import java.util.logging.Logger;

/**
 * A servlet class.
 */
public abstract class AbstractServlet extends HttpServlet {

	private static final Logger log = Logger.getLogger(AbstractServlet.class.getName());
	private static final long serialVersionUID = 42L; // any does; class never serialized
	/**
	 *
	 */
	protected static int lastSessionId = 0; // system and agent are named differently

	/**
	 *
	 */
	public static synchronized int getLastSessionId() {
		return lastSessionId;
	}

	/**
	 *
	 */
	public static void setLastSessionId(int newSessionId) {
		lastSessionId = newSessionId;
	}

	/**
	 *
	 */
	public static synchronized int getNextSessionId() {
		return ++lastSessionId;
	}

	/**
	 *
	 */
	public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		request.setCharacterEncoding("UTF-8");
		response.setCharacterEncoding("UTF-8");

		UserSession us = ensureUserSession(request);
		SessionManager.setThreadLocalSession(us);

		if (ServiceMain.getInstance().isShuttingDown() || (us == null)) {
			displayNullPage(request, response);
		} else {
			myGet(request, response);
		}

		SessionManager.dropThreadLocalSession();
	}

	/**
	 *
	 */
	public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		request.setCharacterEncoding("UTF-8");
		response.setCharacterEncoding("UTF-8");

		UserSession us = ensureUserSession(request);
		SessionManager.setThreadLocalSession(us);

		if (ServiceMain.getInstance().isShuttingDown() || (us == null)) {
			displayNullPage(request, response);
		} else {
			myPost(request, response);
		}

		SessionManager.dropThreadLocalSession();
	}

	/**
	 *
	 */
	protected void myPost(HttpServletRequest request, HttpServletResponse response) throws ServletException,
			IOException {
		// do nothing
	}

	/**
	 *
	 */
	protected UserSession ensureUserSession(HttpServletRequest request) {
		HttpSession httpSession = request.getSession();

		String sessionName = httpSession.getId();
		String siteUrl = getSiteUrl(request); // @TODO Application

		UserSession result = new UserSession(sessionName, siteUrl, httpSession, request.getLocale().getLanguage());

		return result;
	}

	/**
	 *
	 */
	protected void displayNullPage(HttpServletRequest request, HttpServletResponse response) throws ServletException,
			IOException {
		response.setContentType("text/html");

		PrintWriter out = response.getWriter();
		out.print("The system is undergoing maintenance and will be back in a minute. Thank you for your patience!");
		out.close();

		response.setStatus(HttpServletResponse.SC_OK);
	}

	/**
	 *
	 */
	protected void myGet(HttpServletRequest request, HttpServletResponse response) throws ServletException,
			IOException {
		// do nothing
	}

	/**
	 *
	 */
	protected String getSiteUrl(HttpServletRequest request) {
		String result = request.getRequestURL().toString();
		int lastIndex = result.lastIndexOf('/') + 1;
		return result.substring(0, lastIndex);
	}

	/**
	 *
	 */
	protected void redirectRequest(HttpServletResponse response, String link) throws IOException {
		response.setContentType("text/html");
		String newTarget = new String("/" + link + ".html");
		log.config(LogBuilder.createSystemMessage().addParameter("Redirect to", newTarget).toString());
		response.sendRedirect(newTarget);
	}

	/**
	 *
	 */
	protected void configureResponse(Session ctx, HttpServletResponse response, WebPart result) throws IOException {
		long processingTime = ctx.getProcessingTime();
		result.addString("processingTime", StringUtil.asStringInSeconds((processingTime == 0) ? 1 : processingTime));
		log.config(LogBuilder.createSystemMessage().
				addParameter("proctime", String.valueOf(processingTime)).toString());

		response.setContentType("text/html");

		PrintWriter out = response.getWriter();
		result.writeOn(out);
		out.close();

		response.setStatus(HttpServletResponse.SC_OK);
	}

	/**
	 *
	 */
	protected boolean isLocalHost(HttpServletRequest request) {
		String remoteHost = request.getRemoteHost();
		String localHost = null;
		try {
			localHost = InetAddress.getLocalHost().getHostAddress();
		} catch (Exception ex) {
			// ignore
		}
		return remoteHost.equals(localHost) || remoteHost.equals("localhost");
	}

	/**
	 *
	 */
	protected String getRequestArgsAsString(UserSession us, Map args) {
		StringBuffer result = new StringBuffer(96);
		for (Iterator i = args.keySet().iterator(); i.hasNext(); ) {
			String key = i.next().toString();
			String value = us.getAsString(args, key);
			result.append(key + "=" + value);
			if (i.hasNext()) {
				result.append("; ");
			}
		}
		return "[" + result.toString() + "]";
	}

}