001/** 002 * 003 * Copyright the original author or authors 004 * 005 * Licensed under the Apache License, Version 2.0 (the "License"); 006 * you may not use this file except in compliance with the License. 007 * You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.jivesoftware.smackx.jingleold; 018 019import org.jivesoftware.smack.SmackException; 020import org.jivesoftware.smack.packet.IQ; 021 022import org.jivesoftware.smackx.jingleold.packet.Jingle; 023 024/** 025 * Implement the Jingle Session state using the State Behavioral pattern. 026 * (From the book Design Patterns, AKA GoF.) 027 * These classes also employ the Flyweight and Singleton patterns as recommended for the State pattern by GoF. 028 * 029 * There seems to be three ways to go with the State pattern in Java: interface, abstract class and enums. 030 * Most of the accepted models use abstract classes. It wasn't clear to me that any of the three models was 031 * superior, so I went with the most common example. 032 * 033 * @author Jeff Williams 034 */ 035public abstract class JingleSessionState { 036 037 /** 038 * Called when entering the state. 039 */ 040 public static JingleSessionState getInstance() { 041 // Since we can never instantiate this class there is nothing to return (ever). 042 return null; 043 } 044 045 /** 046 * Called when entering the state. 047 */ 048 public abstract void enter(); 049 050 /** 051 * Called when exiting the state. 052 */ 053 public abstract void exit(); 054 055 /** 056 * Process an incoming Jingle Packet. 057 * When you look at the GoF State pattern this method roughly corresponds to example on p310: ProcessOctect(). 058 * @throws InterruptedException 059 */ 060 public abstract IQ processJingle(JingleSession session, Jingle jingle, JingleActionEnum action) throws SmackException, InterruptedException; 061 062 /** 063 * For debugging just emit the short name of the class. 064 */ 065 @Override 066 public String toString() { 067 return this.getClass().getSimpleName(); 068 } 069}