很多聊天室客戶端都使用了xmpp協議。

這個協議被人們詬病很多，但是對於簡單的訊息傳送還是有很大的使用價值的。

XMPP is the open standard for messaging and presence。

gloox is a popular library for the Extensible Messaging and Presence Protocol (XMPP), formerly known as Jabber.

所以寫了一個簡單的例子，如何使用gloox連線伺服器，監聽訊息，以及如何應答。

首先是設定 MessageHandler:

class Bot : public
 
 MessageHandler {
public:
    Bot() {
        JID jid("[email protected]");
        client = new Client( jid, "botpwd" );
        connListener = new ConnListener();
        client->registerMessageHandler( this );
        client->registerConnectionListener(connListener);
        client->connect(true
 
);
    }

這裡我們建立了一個客戶端，有ID和密碼。

接下來，我們需要ConnectionListener就處理連線。
而ConnectionListener一定要registered with 客戶端。這個一會再說。

現在是連線伺服器，我們採用non-bloking的方式。

為了能夠處理訊息，我們要實現handleMessage方法：

virtual void handleMessage( const Message& stanza, MessageSession* session = 0 ) {
    cout << "Received message: "
 
 << stanza << endl;
    Message msg(stanza.subtype(), stanza.from(), "Tell me more about " + stanza.body() );
    client->send( msg );
}

這時候我們需要connectlisenner來處理連線，需要重寫純虛擬函式：

class ConnListener : public ConnectionListener {
public:
    virtual void onConnect() {
        cout << "ConnListener::onConnect()" << endl;
    }
    virtual void onDisconnect(ConnectionError e) {
        cout << "ConnListener::onDisconnect() " << e << endl;
    }
    virtual bool onTLSConnect(const CertInfo& info) {
        cout << "ConnListener::onTLSConnect()" << endl;
        return true;
    }
};

上面程式碼重要的是onTLSConnect()函式。

全部程式碼：

#include <iostream>
#include <string>
#include <gloox/client.h>
#include <gloox/message.h>
#include <gloox/messagehandler.h>
#include <gloox/connectionlistener.h>

using namespace std;
using namespace gloox;

ostream& operator<<(ostream& os, Message::MessageType type) {
    switch (type) {
        case Message::Chat:
            os << "Chat";
            break;
        case Message::Error:
            os << "Error";
            break;
        case Message::Groupchat:
            os << "Groupchat";
            break;
        case Message::Headline:
            os << "Headline";
            break;
        case Message::Normal:
            os << "Normal";
            break;
        case Message::Invalid:
            os << "Invalid";
            break;
        default:
            os << "unknown type";
            break;
    }
}

ostream& operator<<(ostream& os, const Message& stanza) {
    os << "type:'" << stanza.subtype() <<  "' from:'" << stanza.from().full() << "' body:'" << stanza.body() << "'";
    return os;
}

class ConnListener : public ConnectionListener {
public:
    virtual void onConnect() {
        cout << "ConnListener::onConnect()" << endl;
    }
    virtual void onDisconnect(ConnectionError e) {
        cout << "ConnListener::onDisconnect() " << e << endl;
    }
    virtual bool onTLSConnect(const CertInfo& info) {
        cout << "ConnListener::onTLSConnect()" << endl;
        return true;
    }
};

class Bot : public MessageHandler {
public:
    Bot() {
        JID jid("[email protected]");
        client = new Client( jid, "botpwd" );
        connListener = new ConnListener();
        client->registerMessageHandler( this );
        client->registerConnectionListener(connListener);
        client->connect(true);
    }

    ~Bot() {
        delete client;
        delete connListener;
    }

    virtual void handleMessage( const Message& stanza, MessageSession* session = 0 ) {
        cout << "Received message: " << stanza << endl;
        Message msg(Message::Chat, stanza.from(), "Tell me more about " + stanza.body() );
        client->send( msg );
    }

private:
   Client* client;
   ConnListener* connListener;
};

int main() {
    Bot b;
}