RabbitMQ学习之ConntectionFactory与Conntection的认知

在发送和接收消息重要的类有：ConnectionFactory， Connection，Channel和 QueueingConsumer。

ConntectionFactory类是方便创建与AMQP代理相关联的Connection；下面来看看ConntectionFactory是如何创建一个Contention.首先通过new ConnectionFactory()创建一个ConnectionFactory；并设置此连接工厂的主机设置为broke IP。通过ConnectionFactory的newConnection()方法 创建一个Connection; newConnection方法通过得到当前连接的地址及端口号来获得一个Address，通过createFrameHandler的方法 来得到FrameHandler;再通过new AMQConnection(this, frameHandler)来得到Connection并启动。
    代码清单1创建Connection的源码（ConnectionFactory.Java中）

protected FrameHandler createFrameHandler(Address addr)
        throws IOException {

        String hostName = addr.getHost();//获取主机IP
        int portNumber = portOrDefault(addr.getPort());//获取端口
        Socket socket = null;
        try {
            socket = factory.createSocket();
            configureSocket(socket);
            socket.connect(new InetSocketAddress(hostName, portNumber),
                    connectionTimeout);
            return createFrameHandler(socket);
        } catch (IOException ioe) {
            quietTrySocketClose(socket);
            throw ioe;
        }
    }

    private static void quietTrySocketClose(Socket socket) {
        if (socket != null)
            try { socket.close(); } catch (Exception _) {/*ignore exceptions*/}
    }

    protected FrameHandler createFrameHandler(Socket sock)
        throws IOException
    {
        return new SocketFrameHandler(sock);
    }

    /**
     *  Provides a hook to insert custom configuration of the sockets
     *  used to connect to an AMQP server before they connect.
     *
     *  The default behaviour of this method is to disable Nagle's
     *  algorithm to get more consistently low latency.  However it
     *  may be overridden freely and there is no requirement to retain
     *  this behaviour.
     *
     *  @param socket The socket that is to be used for the Connection
     */
    protected void configureSocket(Socket socket) throws IOException{
        // disable Nagle's algorithm, for more consistently low latency
        socket.setTcpNoDelay(true);
    }

    /**
     * Create a new broker connection
     * @param addrs an array of known broker addresses (hostname/port pairs) to try in order
     * @return an interface to the connection
     * @throws IOException if it encounters a problem
     */
    public Connection newConnection(Address[] addrs) throws IOException {
        return newConnection(null, addrs);
    }

    /**
     * Create a new broker connection
     * @param executor thread execution service for consumers on the connection
     * @param addrs an array of known broker addresses (hostname/port pairs) to try in order
     * @return an interface to the connection
     * @throws IOException if it encounters a problem
     */
    public Connection newConnection(ExecutorService executor, Address[] addrs)
        throws IOException
    {
        IOException lastException = null;
        for (Address addr : addrs) {
            try {
                FrameHandler frameHandler = createFrameHandler(addr);
                AMQConnection conn =
                    new AMQConnection(username,
                                      password,
                                      frameHandler,
                                      executor,
                                      virtualHost,
                                      getClientProperties(),
                                      requestedFrameMax,
                                      requestedChannelMax,
                                      requestedHeartbeat,
                                      saslConfig);
                conn.start();
                return conn;
            } catch (IOException e) {
                lastException = e;
            }
        }

        throw (lastException != null) ? lastException
                                      : new IOException("failed to connect");
    }

    /**
     * Create a new broker connection
     * @return an interface to the connection
     * @throws IOException if it encounters a problem
     */
    public Connection newConnection() throws IOException {
        return newConnection(null,
                             new Address[] {new Address(getHost(), getPort())}
                            );
    }

    /**
     * Create a new broker connection
     * @param executor thread execution service for consumers on the connection
     * @return an interface to the connection
     * @throws IOException if it encounters a problem
     */
    public Connection newConnection(ExecutorService executor) throws IOException {
        return newConnection(executor,
                             new Address[] {new Address(getHost(), getPort())}
                            );
    }

  代码清单2 连接启动

/**
     * Start up the connection, including the MainLoop thread.
     * Sends the protocol
     * version negotiation header, and runs through
     * Connection.Start/.StartOk, Connection.Tune/.TuneOk, and then
     * calls Connection.Open and waits for the OpenOk. Sets heart-beat
     * and frame max values after tuning has taken place.
     * @throws IOException if an error is encountered
     * either before, or during, protocol negotiation;
     * sub-classes {@link ProtocolVersionMismatchException} and
     * {@link PossibleAuthenticationFailureException} will be thrown in the
     * corresponding circumstances. If an exception is thrown, connection
     * resources allocated can all be garbage collected when the connection
     * object is no longer referenced.
     */
    public void start()
        throws IOException
    {
        this._running = true;
        // Make sure that the first thing we do is to send the header,
        // which should cause any socket errors to show up for us, rather
        // than risking them pop out in the MainLoop
        AMQChannel.SimpleBlockingRpcContinuation connStartBlocker =
            new AMQChannel.SimpleBlockingRpcContinuation();
        // We enqueue an RPC continuation here without sending an RPC
        // request, since the protocol specifies that after sending
        // the version negotiation header, the client (connection
        // initiator) is to wait for a connection.start method to
        // arrive.
        _channel0.enqueueRpc(connStartBlocker);
        try {
            // The following two lines are akin to AMQChannel's
            // transmit() method for this pseudo-RPC.
            _frameHandler.setTimeout(HANDSHAKE_TIMEOUT);
            _frameHandler.sendHeader();
        } catch (IOException ioe) {
            _frameHandler.close();
            throw ioe;
        }

        // start the main loop going
        new MainLoop("AMQP Connection " + getHostAddress() + ":" + getPort()).start();
        // after this point clear-up of MainLoop is triggered by closing the frameHandler.

        AMQP.Connection.Start connStart = null;
        AMQP.Connection.Tune connTune = null;
        try {
            connStart =
                (AMQP.Connection.Start) connStartBlocker.getReply().getMethod();

            _serverProperties = Collections.unmodifiableMap(connStart.getServerProperties());

            Version serverVersion =
                new Version(connStart.getVersionMajor(),
                            connStart.getVersionMinor());

            if (!Version.checkVersion(clientVersion, serverVersion)) {
                throw new ProtocolVersionMismatchException(clientVersion,
                                                           serverVersion);
            }

            String[] mechanisms = connStart.getMechanisms().toString().split(" ");
            SaslMechanism sm = this.saslConfig.getSaslMechanism(mechanisms);
            if (sm == null) {
                throw new IOException("No compatible authentication mechanism found - " +
                        "server offered [" + connStart.getMechanisms() + "]");
            }

            LongString challenge = null;
            LongString response = sm.handleChallenge(null, this.username, this.password);

            do {
                Method method = (challenge == null)
                    ? new AMQP.Connection.StartOk.Builder()
                                    .clientProperties(_clientProperties)
                                    .mechanism(sm.getName())
                                    .response(response)
                          .build()
                    : new AMQP.Connection.SecureOk.Builder().response(response).build();

                try {
                    Method serverResponse = _channel0.rpc(method).getMethod();
                    if (serverResponse instanceof AMQP.Connection.Tune) {
                        connTune = (AMQP.Connection.Tune) serverResponse;
                    } else {
                        challenge = ((AMQP.Connection.Secure) serverResponse).getChallenge();
                        response = sm.handleChallenge(challenge, this.username, this.password);
                    }
                } catch (ShutdownSignalException e) {
                    throw new PossibleAuthenticationFailureException(e);
                }
            } while (connTune == null);
        } catch (ShutdownSignalException sse) {
            _frameHandler.close();
            throw AMQChannel.wrap(sse);
        } catch(IOException ioe) {
            _frameHandler.close();
            throw ioe;
        }

        try {
            int channelMax =
                negotiatedMaxValue(this.requestedChannelMax,
                                   connTune.getChannelMax());
            _channelManager = new ChannelManager(this._workService, channelMax);

            int frameMax =
                negotiatedMaxValue(this.requestedFrameMax,
                                   connTune.getFrameMax());
            this._frameMax = frameMax;

            int heartbeat =
                negotiatedMaxValue(this.requestedHeartbeat,
                                   connTune.getHeartbeat());

            setHeartbeat(heartbeat);

            _channel0.transmit(new AMQP.Connection.TuneOk.Builder()
                                .channelMax(channelMax)
                                .frameMax(frameMax)
                                .heartbeat(heartbeat)
                              .build());
            _channel0.exnWrappingRpc(new AMQP.Connection.Open.Builder()
                                      .virtualHost(_virtualHost)
                                    .build());
        } catch (IOException ioe) {
            _heartbeatSender.shutdown();
            _frameHandler.close();
            throw ioe;
        } catch (ShutdownSignalException sse) {
            _heartbeatSender.shutdown();
            _frameHandler.close();
            throw AMQChannel.wrap(sse);
        }

        // We can now respond to errors having finished tailoring the connection
        this._inConnectionNegotiation = false;

        return;
    }

转载：http://wubin850219.iteye.com/blog/1007984