Smack/source/org/jivesoftware/smack/Chat.java

/**
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 *
 * Copyright (C) 2002-2003 Jive Software. All rights reserved.
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 * The Jive Software License (based on Apache Software License, Version 1.1)
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 * modification, are permitted provided that the following conditions
 * are met:
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 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
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 * 2. Redistributions in binary form must reproduce the above copyright
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 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by
 *        Jive Software (http://www.jivesoftware.com)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
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 * 4. The names "Smack" and "Jive Software" must not be used to
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 * 5. Products derived from this software may not be called "Smack",
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package org.jivesoftware.smack;

import org.jivesoftware.smack.packet.Message;
import org.jivesoftware.smack.util.StringUtils;
import org.jivesoftware.smack.filter.ThreadFilter;

/**
 * A chat is a series of messages sent between two users. Each chat has
 * a unique ID, which is used to track which messages are part of the chat.
 *
 * @see XMPPConnection#createChat(String)
 * @author Matt Tucker
 */
public class Chat {

    /**
     * A prefix helps to make sure that ID's are unique across mutliple instances.
     */
    private static String prefix = StringUtils.randomString(3);

    /**
     * Keeps track of the current increment, which is appended to the prefix to
     * forum a unique ID.
     */
    private static long id = 0;

    /**
     * Returns the next unique id. Each id made up of a short alphanumeric
     * prefix along with a unique numeric value.
     *
     * @return the next id.
     */
    private static synchronized String nextID() {
        return prefix + Long.toString(id++);
    }

    private XMPPConnection connection;
    private String chatID;
    private String participant;
    private PacketCollector messageCollector;

    /**
     * Creates a new chat with the specified user.
     *
     * @param connection the connection the chat will use.
     * @param participant the user to chat with.
     */
    public Chat(XMPPConnection connection, String participant) {
        this.connection = connection;
        this.participant = participant;
        // Automatically assign the next chat ID.
        chatID = nextID();

        messageCollector = connection.getPacketReader().createPacketCollector(
                new ThreadFilter(chatID));
    }

    /**
     * Creates a new chat with the specified user and chat ID (the XMPP "thread).
     *
     * @param connection the connection the chat will use.
     * @param participant the user to chat with.
     * @param chatID the chat ID to use.
     */
    public Chat(XMPPConnection connection, String participant, String chatID) {
        this.connection = connection;
        this.participant = participant;
        this.chatID = chatID;

        messageCollector = connection.getPacketReader().createPacketCollector(
                new ThreadFilter(chatID));
    }

    /**
     * Returns the unique id of this chat, which corresponds to the
     * <tt>thread</tt> field of XMPP messages.
     *
     * @return the unique ID of this chat.
     */
    public String getChatID() {
        return chatID;
    }

    /**
     * Returns the name of the user the chat is with.
     *
     * @return the name of the user the chat is occuring with.
     */
    public String getParticipant() {
        return participant;
    }

    /**
     * Sends the specified text as a message to the other chat participant.
     * This is a convenience method for:
     *
     * <pre>
     *     Message message = chat.createMessage();
     *     message.setBody(messageText);
     *     chat.sendMessage(message);
     * </pre>
     *
     * @param text the text to send.
     * @throws XMPPException if sending the message fails.
     */
    public void sendMessage(String text) throws XMPPException {
        Message message = createMessage();
        message.setBody(text);
        connection.getPacketWriter().sendPacket(message);
    }

    /**
     * Creates a new Message to the chat participant. The message returned
     * will have its thread property set with this chat ID.
     *
     * @return a new message addressed to the chat participant and
     *      using the correct thread value.
     * @see #sendMessage(Message)
     */
    public Message createMessage() {
        Message message = new Message(participant, Message.CHAT);
        message.setThread(chatID);
        return message;
    }

    /**
     * Sends a message to the other chat participant. The thread property of
     * the message will automatically set to this chat ID in case the Message
     * was not created using the {@link #createMessage() createMessage} method.
     *
     * @param message
     * @throws XMPPException
     */
    public void sendMessage(Message message) throws XMPPException {
        // Force the chatID since the user elected to send the message
        // through this chat object.
        message.setThread(chatID);
        connection.getPacketWriter().sendPacket(message);
    }

    /**
     * Polls for and returns the next message, or <tt>null</tt> if there isn't
     * a message immediately available. This method provides significantly different
     * functionalty than the {@link #nextMessage()} method since it's non-blocking.
     * In other words, the method call will always return immediately, whereas the
     * nextMessage method will return only when a message is available (or after
     * a specific timeout).
     *
     * @return the next message if one is immediately available and
     *      <tt>null</tt> otherwise.
     */
    public Message pollMessage() {
        return (Message)messageCollector.pollResult();
    }

    /**
     * Returns the next available message in the chat. The method will block
     * indefinitely (won't return) until a message is available.
     *
     * @return the next message.
     */
    public Message nextMessage() {
        return (Message)messageCollector.nextResult();
    }

    /**
     * Returns the next available message in the chat. The method will block
     * for up to the timeout. If a message still isn't available then, <tt>null</tt>
     * will be returned.
     *
     * @param timeout the maximum amount of time to wait for the next message.
     * @return the next message, or <tt>null</tt> if the timeout elapses without a
     *      message becoming available.
     */
    public Message nextMessage(long timeout) {
        return (Message)messageCollector.nextResult(timeout);
    }
}