rabbitmq学习7:ConntectionFactory与Conntection的认知

 

  从前面几小节的学习，我们可能知道在发送和接收消息重要的类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localhost。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。如代码清单7-1所示。

    代码清单7-1 创建Connection的源码（ConnectionFactory.Java中）

 

  1. protected FrameHandler createFrameHandler(Address addr)
  2.         throws IOException {
  3.
  4.         String hostName = addr.getHost();
  5.         int portNumber = portOrDefault(addr.getPort());//得到端口号
  6.         Socket socket = factory.createSocket();
  7.         configureSocket(socket);//这里Socket通过TCP无迟延的协议
  8.         socket.connect(new InetSocketAddress(hostName, portNumber), connectionTimeout);
  9.         return createFrameHandler(socket);
 10.     }
 11.
 12.     protected FrameHandler createFrameHandler(Socket sock)
 13.         throws IOException
 14.     {
 15.         return new SocketFrameHandler(sock);
 16.     }
 17.
 18.     /**
 19.      *  Provides a hook to insert custom configuration of the sockets
 20.      *  used to connect to an AMQP server before they connect.
 21.      *
 22.      *  The default behaviour of this method is to disable Nagle's
 23.      *  algorithm to get more consistently low latency.  However it
 24.      *  may be overridden freely and there is no requirement to retain
 25.      *  this behaviour.
 26.      *
 27.      *  @param socket The socket that is to be used for the Connection
 28.      */
 29.     protected void configureSocket(Socket socket) throws IOException{
 30.         // disable Nagle's algorithm, for more consistently low latency
 31.         socket.setTcpNoDelay(true);
 32.     }
 33.
 34.     /**
 35.      * Create a new broker connection
 36.      * @param addrs an array of known broker addresses (hostname/port pairs) to try in order
 37.      * @return an interface to the connection
 38.      * @throws IOException if it encounters a problem
 39.      */
 40.     public Connection newConnection(Address[] addrs)
 41.         throws IOException
 42.     {
 43.         IOException lastException = null;
 44.         for (Address addr : addrs) {
 45.             try {
 46.                 FrameHandler frameHandler = createFrameHandler(addr);
 47.                 AMQConnection conn = new AMQConnection(this,
 48.                                                        frameHandler);
 49.                 conn.start();
 50.                 return conn;
 51.             } catch (IOException e) {
 52.                 lastException = e;
 53.             }
 54.         }
 55.
 56.         if (lastException == null) {
 57.             throw new IOException("failed to connect");
 58.         } else {
 59.             throw lastException;
 60.         }
 61.     }
 62.
 63.     /**
 64.      * Create a new broker connection
 65.      * @return an interface to the connection
 66.      * @throws IOException if it encounters a problem
 67.      */
 68.     public Connection newConnection() throws IOException {
 69.         return newConnection(new Address[] {
 70.                                  new Address(getHost(), getPort())});
 71.     }

 

代码清单7-2 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 heartbeat
      * and frame max values after tuning has taken place.
      * @throws java.io.IOException if an error is encountered; IOException
      * subtypes {@link ProtocolVersionMismatchException} and
      * {@link PossibleAuthenticationFailureException} will be thrown in the
      * corresponding circumstances.
      */
     public void start()
         throws IOException
     {
         // 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);
         // The following two lines are akin to AMQChannel's
         // transmit() method for this pseudo-RPC.
         _frameHandler.setTimeout(HANDSHAKE_TIMEOUT);
         _frameHandler.sendHeader();

         // start the main loop going
         Thread ml = new MainLoop();
         ml.setName("AMQP Connection " + getHostAddress() + ":" + getPort());
         ml.start();

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

             _serverProperties = connStart.getServerProperties();

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

             if (!Version.checkVersion(clientVersion, serverVersion)) {
                 _frameHandler.close(); //this will cause mainLoop to terminate
                 throw new ProtocolVersionMismatchException(clientVersion,
                                                            serverVersion);
             }
         } catch (ShutdownSignalException sse) {
             throw AMQChannel.wrap(sse);
         }

         String[] mechanisms = connStart.getMechanisms().toString().split(" ");
         SaslMechanism sm = _factory.getSaslConfig().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, _factory);

         AMQP.Connection.Tune connTune = null;
         do {
             Method method = (challenge == null)
                 ? new AMQImpl.Connection.StartOk(_clientProperties,
                                                  sm.getName(),
                                                  response, "en_US")
                 : new AMQImpl.Connection.SecureOk(response);

             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, _factory);
                 }
             } catch (ShutdownSignalException e) {
                 throw new PossibleAuthenticationFailureException(e);
             }
         } while (connTune == null);

         int channelMax =
             negotiatedMaxValue(_factory.getRequestedChannelMax(),
                                connTune.getChannelMax());
         _channelManager = new ChannelManager(channelMax);

         int frameMax =
             negotiatedMaxValue(_factory.getRequestedFrameMax(),
                                connTune.getFrameMax());
         setFrameMax(frameMax);

         int heartbeat =
             negotiatedMaxValue(_factory.getRequestedHeartbeat(),
                                connTune.getHeartbeat());
         setHeartbeat(heartbeat);

         _channel0.transmit(new AMQImpl.Connection.TuneOk(channelMax,
                                                          frameMax,
                                                          heartbeat));
         // 0.9.1: insist [on not being redirected] is deprecated, but
         // still in generated code; just pass a dummy value here
         _channel0.exnWrappingRpc(new AMQImpl.Connection.Open(_virtualHost,
                                                             "",
                                                             false)).getMethod();
         return;
     }