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在android里面用的smack包其實(shí)叫做asmack，該包提供了兩種不同的連接方式：socket和httpclient。該并且提供了很多操作xmpp協(xié)議的API，也方便各種不同自定義協(xié)議的擴(kuò)展。我們不需要自己重新去定義一套接收機(jī)制來擴(kuò)展新的協(xié)議，只需繼承然后在類里處理自己的協(xié)議就可以了。而本文今天主要說兩點(diǎn)，一點(diǎn)就是消息是如何接收的，另一點(diǎn)就是消息是如何通知事件的。

總的思路

1.使用socket連接服務(wù)器

2.將XmlPullParser的數(shù)據(jù)源關(guān)聯(lián)到socket的InputStream

3.啟動(dòng)線程不斷循環(huán)處理消息

4.將接收到的消息解析xml處理封裝好成一個(gè)Packet包

5.將包廣播給所有注冊事件監(jiān)聽的類

逐步擊破

（聲明在看下面的文章時(shí)，最好先理解一下smack的使用，這樣才能達(dá)到深入的理解）

（謹(jǐn)記：上圖只顯示本文章解釋所要用到的類和方法，減縮了一些跟本文主題無關(guān)的代碼，只留一條貫穿著從建立連接到接收消息的線。）

解析這塊東西打算從最初的調(diào)用開始作為入口，抽絲剝繭，逐步揭開。

PacketListener packetListener = new PacketListener() { @Override public void processPacket(Packet packet) { System.out .println("Activity----processPacket" + packet.toXML()); } };

PacketFilter packetFilter = new PacketFilter() {@Overridepublic boolean accept(Packet packet) {System.out.println("Activity----accept" + packet.toXML());return true;}};

解釋：創(chuàng)建包的監(jiān)聽以及包的過濾，當(dāng)有消息到時(shí)就會廣播到所有注冊的監(jiān)聽，當(dāng)然前提是要通過packetFilter的過濾。

connection = new XMPPConnection();

XMPPConnection在這構(gòu)造函數(shù)里面主要配置ip地址和端口（super(new ConnectionConfiguration("169.254.141.109", 9991));）

connection.addPacketListener(packetListener, packetFilter); connection.connect();

注冊監(jiān)聽，開始初始化連接。

public void connect() { // Stablishes the connection, readers and writers connectUsingConfiguration(config); } 5.

private void connectUsingConfiguration(ConnectionConfiguration config) { String host = config.getHost(); int port = config.getPort(); try { this.socket = new Socket(host, port); } catch (UnknownHostException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } initConnection(); } 通過之前設(shè)置的ip和端口，建立socket對象

protected void initDebugger() { Class<?> debuggerClass = null; try { debuggerClass = Class.forName("com.simualteSmack.ConsoleDebugger");

Constructor<?> constructor = debuggerClass.getConstructor(Connection.class, Writer.class, Reader.class);debugger = (SmackDebugger) constructor.newInstance(this, writer,reader);reader = debugger.getReader();} catch (ClassNotFoundException e1) {// TODO Auto-generated catch blocke1.printStackTrace();} catch (Exception e) {throw new IllegalArgumentException("Can't initialize the configured debugger!", e);} }

private void initReaderAndWriter() { try { reader = new BufferedReader(new InputStreamReader(socket .getInputStream(), "UTF-8")); } catch (UnsupportedEncodingException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } initDebugger(); } private void initConnection() { // Set the reader and writer instance variables initReaderAndWriter();

packetReader = new PacketReader(this);addPacketListener(debugger.getReaderListener(), null); // Start the packet reader. The startup() method will block until we // get an opening stream packet back from server. packetReader.startup();

} 從三個(gè)方法可以看出，建立reader和writer的對象關(guān)聯(lián)到socket的InputStream，實(shí)例化ConsoleDebugger，該類主要是打印出接收到的消息，給reader設(shè)置了一個(gè)消息的監(jiān)聽。接著建立PacketReader對象，并啟動(dòng)。PacketReader主要負(fù)責(zé)消息的處理和通知

public class PacketReader { private ExecutorService listenerExecutor; private boolean done; private XMPPConnection connection; private XmlPullParser parser; private Thread readerThread;

protected PacketReader(final XMPPConnection connection) {this.connection = connection;this.init(); }/*** Initializes the reader in order to be used. The reader is initialized* during the first connection and when reconnecting due to an abruptly* disconnection.*/ protected void init() {done = false;readerThread = new Thread() {public void run() {parsePackets(this);}};readerThread.setName("Smack Packet Reader ");readerThread.setDaemon(true);// create an executor to deliver incoming packets to listeners.// we will use a single thread with an unbounded queue.listenerExecutor = Executors.newSingleThreadExecutor(new ThreadFactory() {@Overridepublic Thread newThread(Runnable r) {Thread thread = new Thread(r,"smack listener processor");thread.setDaemon(true);return thread;}});resetParser(); }/*** Starts the packet reader thread and returns once a connection to the* server has been established. A connection will be attempted for a maximum* of five seconds. An XMPPException will be thrown if the connection fails.* */ public void startup() {readerThread.start(); }/*** Shuts the packet reader down.*/ public void shutdown() {done = true;// Shut down the listener executor.listenerExecutor.shutdown(); }private void resetParser() {try {parser = XmlPullParserFactory.newInstance().newPullParser();parser.setFeature(XmlPullParser.FEATURE_PROCESS_NAMESPACES, true);parser.setInput(connection.reader);} catch (XmlPullParserException xppe) {xppe.printStackTrace();} }/*** Parse top-level packets in order to process them further.* * @param thread* the thread that is being used by the reader to parse incoming* packets.*/ private void parsePackets(Thread thread) {try {int eventType = parser.getEventType();do {if (eventType == XmlPullParser.START_TAG) {if (parser.getName().equals("message")) {processPacket(PacketParserUtils.parseMessage(parser));}System.out.println("START_TAG");} else if (eventType == XmlPullParser.END_TAG) {System.out.println("END_TAG");}eventType = parser.next();} while (!done && eventType != XmlPullParser.END_DOCUMENT&& thread == readerThread);} catch (Exception e) {e.printStackTrace();if (!done) {}} }private void processPacket(Packet packet) {if (packet == null) {return;}// Loop through all collectors and notify the appropriate ones.for (PacketCollector collector : connection.getPacketCollectors()) {collector.processPacket(packet);}// Deliver the incoming packet to listeners.listenerExecutor.submit(new ListenerNotification(packet)); }/*** A runnable to notify all listeners of a packet.*/ private class ListenerNotification implements Runnable {private Packet packet;public ListenerNotification(Packet packet) {this.packet = packet;}public void run() {for (ListenerWrapper listenerWrapper : connection.recvListeners.values()) {listenerWrapper.notifyListener(packet);}} }

} 創(chuàng)建該類時(shí)就初始化線程和ExecutorService ，接著調(diào)用resetParser() 方法為parser設(shè)置輸入源（這里是重點(diǎn)，parser的數(shù)據(jù)都是通過這里獲取），調(diào)用startup啟動(dòng)線程，循環(huán)監(jiān)聽parser，如果接收到消息根據(jù)消息協(xié)議的不同將調(diào)用PacketParserUtils類里的不同方法，這里調(diào)用parseMessage（）該方法主要處理message的消息，在該方法里分析message消息并返回packet包。返回的包將調(diào)用processPacket方法，先通知所有注冊了PacketCollector的監(jiān)聽，接著消息（listenerExecutor.submit(new ListenerNotification(packet)); ）傳遞給所有注冊了PacketListener的監(jiān)聽。這樣在activity開始之前注冊的那個(gè)監(jiān)聽事件就會觸發(fā)，從而完成了整個(gè)流程。

7以上.

剩下的就是一些輔助包，很簡單。比如PacketCollector 這個(gè)類，它的用處主要用來處理一些需要在發(fā)送后需要等待一個(gè)答復(fù)這樣的請求。

protected synchronized void processPacket(Packet packet) { System.out.println("PacketCollector---processPacket"); if (packet == null) { return; } if (packetFilter == null || packetFilter.accept(packet)) { while (!resultQueue.offer(packet)) { resultQueue.poll(); } } } public Packet nextResult(long timeout) { long endTime = System.currentTimeMillis() + timeout; System.out.println("nextResult"); do { try { return resultQueue.poll(timeout, TimeUnit.MILLISECONDS); } catch (InterruptedException e) { /* ignore */ } } while (System.currentTimeMillis() < endTime); return null; } 該方法就是將獲取到的包，先過濾然后放到隊(duì)列里，最后通過nextResult來獲取包，這樣就完成一個(gè)請求收一個(gè)答復(fù)。

這樣整個(gè)流程就完成了，最后總結(jié)一下，如圖（就這么簡單^0^）：

項(xiàng)目下載(只有客戶端的，服務(wù)端的就是一個(gè)簡單的socket接受，為了鍛煉一下大家的編寫代碼的能力，服務(wù)器那個(gè)只能自己寫咯^0^，其實(shí)是懶得上傳了，代碼很簡單的)

http://files.cnblogs.com/not-code/simualteSmack.zip

本文為原創(chuàng)，如需轉(zhuǎn)載，請注明作者和出處，謝謝！

出處：http://www.cnblogs.com/not-code/archive/2011/08/01/2124340.html

轉(zhuǎn)載于:https://my.oschina.net/yuanxulong/blog/350067

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