001/* 002 * GWTEventService 003 * Copyright (c) 2011 and beyond, strawbill UG (haftungsbeschr?nkt) 004 * 005 * This is free software; you can redistribute it and/or modify it 006 * under the terms of the GNU Lesser General Public License as 007 * published by the Free Software Foundation; either version 3 of 008 * the License, or (at your option) any later version. 009 * Other licensing for GWTEventService may also be possible on request. 010 * Please view the license.txt of the project for more information. 011 * 012 * This software 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 GNU 015 * Lesser General Public License for more details. 016 * 017 * You should have received a copy of the GNU Lesser General Public 018 * License along with this software; if not, write to the Free 019 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 020 * 02110-1301 USA, or see the FSF site: http://www.fsf.org. 021 */ 022package de.novanic.eventservice.service.connection.id; 023 024import de.novanic.eventservice.client.config.ConfigurationException; 025 026import javax.servlet.http.HttpServletRequest; 027import java.util.Random; 028 029/** 030 * A {@link de.novanic.eventservice.service.connection.id.ConnectionIdGenerator} generates unique ids which are used to 031 * identify the connected clients / users. 032 * 033 * That implementation of {@link de.novanic.eventservice.service.connection.id.ConnectionIdGenerator} uses and extends the 034 * session ids to generate a unique connection / client id. That allows the user / client to use more than one browser 035 * instance for the same application (multiple session ids / session sharing). 036 * 037 * @author sstrohschein 038 * <br>Date: 28.03.2010 039 * <br>Time: 23:34:39 040 */ 041public class SessionExtendedConnectionIdGenerator implements ConnectionIdGenerator 042{ 043 private Random myRandomizer; 044 045 /** 046 * Creates a new instance of {@link de.novanic.eventservice.service.connection.id.SessionExtendedConnectionIdGenerator} 047 * and initializes the random number generation. 048 */ 049 public SessionExtendedConnectionIdGenerator() { 050 myRandomizer = new Random(); 051 } 052 053 /** 054 * Generates a new connection / client id. 055 * The {@link de.novanic.eventservice.service.connection.id.SessionExtendedConnectionIdGenerator} creates a new session with 056 * that call when no session is available. The session id will be extended with a random number to support multiple session ids / session sharing. 057 * @param aRequest request from the client 058 * @return unique connection / client id 059 */ 060 public String generateConnectionId(HttpServletRequest aRequest) { 061 return aRequest.getSession(true).getId() + myRandomizer.nextInt(); 062 } 063 064 /** 065 * Returns the previous generated connection / client id 066 * (see {@link de.novanic.eventservice.service.connection.id.ConnectionIdGenerator#generateConnectionId(javax.servlet.http.HttpServletRequest)}) 067 * without generating a new connection / client id. 068 * @see de.novanic.eventservice.service.connection.id.ConnectionIdGenerator#generateConnectionId(javax.servlet.http.HttpServletRequest) 069 * @param aRequest request 070 * @return the previous generated connection / client id for the specific client 071 */ 072 public String getConnectionId(HttpServletRequest aRequest) { 073 final String theConnectionId = aRequest.getParameter("id"); 074 if(theConnectionId == null) { 075 throw new ConfigurationException("A client id was requested without generating a connection id first or the connection id was not transferred with the request!"); 076 } 077 return theConnectionId; 078 } 079}