本文编写，参考：https://my.oschina.net/bieber/blog/725646

producer Send()的Message最终将由broker处理，处理类为：SendMessageProcessor ,处理方法：processRequet.

public class SendMessageProcessor extends AbstractSendMessageProcessor implements NettyRequestProcessor {
      private List
    
      consumeMessageHookList;     public SendMessageProcessor(final BrokerController brokerController) {
          super(brokerController);     }     @Override     public RemotingCommand processRequest(ChannelHandlerContext ctx, RemotingCommand request) throws RemotingCommandException {} 上述方法，并不是直接处理消息，而是交由MessageStore处理，相关代码如下：
    

MessageExtBrokerInner msgInner = new MessageExtBrokerInner(); msgInner.setTopic(requestHeader.getTopic()); msgInner.setQueueId(queueIdInt); //...... PutMessageResult putMessageResult = this.brokerController.getMessageStore().putMessage(msgInner); 然而MessageStore也不直接持久化消息，转交给 CommitLog

long beginTime = this.getSystemClock().now(); PutMessageResult result = this.commitLog.putMessages(messageExtBatch); 从MappedFileQueue中取出最新的一条：

MappedFile mappedFile = this.mappedFileQueue.getLastMappedFile();  //写消息

result = mappedFile.appendMessages(messageExtBatch, this.appendMessageCallback);   //持久化到磁盘,最终通过FileChannel持久化到文件 handleDiskFlush(result, putMessageResult, messageExtBatch); handleHA(result, putMessageResult, messageExtBatch); 2.cousumer 从broker读消息。 消费者从broker读取消息经由PullMessageProcessor类处理的，processRequest()方法处理请求：

RemotingCommand processRequest(final Channel channel, RemotingCommand request, boolean brokerAllowSuspend) 经过一系列的判断处理，之后交由 MessageStore：

final GetMessageResult getMessageResult =     this.brokerController.getMessageStore().getMessage(requestHeader.getConsumerGroup(), requestHeader.getTopic(),         requestHeader.getQueueId(), requestHeader.getQueueOffset(), requestHeader.getMaxMsgNums(), messageFilter); 读取消息。 之后交由commitLog，读出消息，

SelectMappedBufferResult selectResult = this.commitLog.getMessage(offsetPy, sizePy);

可以看到是先从ConsumerQueue中获取消息索引，然后再从commitlog中读取消息内容。这些内容也是在存储消息的时候写入的。

相关也可参考：http://jm.taobao.org/2017/01/12/rocketmq-quick-start-in-10-minutes/