实际路由注册是在org.apache.out.BrokerOuterAPI#registerBrokerAll中实现

public List<RegisterBrokerResult> registerBrokerAll(
    final String clusterName,
    final String brokerAddr,
    final String brokerName,
    final long brokerId,
    final String haServerAddr,
    final TopicConfigSerializeWrapper topicConfigWrapper,
    final List<String> filterServerList,
    final boolean oneway,
    final int timeoutMills,
    final boolean compressed) {
​
    final List<RegisterBrokerResult> registerBrokerResultList = new CopyOnWriteArrayList<>();
    //获取nameserver地址列表
    List<String> nameServerAddressList = this.remotingClient.getNameServerAddressList();
    if (nameServerAddressList != null && nameServerAddressList.size() > 0) {
    /**
      *封装请求包头start
      *封装请求包头，主要封装broker相关信息
    **/
        final RegisterBrokerRequestHeader requestHeader = new RegisterBrokerRequestHeader();
        requestHeader.setBrokerAddr(brokerAddr);
        requestHeader.setBrokerId(brokerId);
        requestHeader.setBrokerName(brokerName);
        requestHeader.setClusterName(clusterName);
        requestHeader.setHaServerAddr(haServerAddr);
        requestHeader.setCompressed(compressed);
    //封装requestBody，包括topic和filterServerList相关信息
        RegisterBrokerBody requestBody = new RegisterBrokerBody();
        requestBody.setTopicConfigSerializeWrapper(topicConfigWrapper);
        requestBody.setFilterServerList(filterServerList);
        final byte[] body = requestBody.encode(compressed);
        final int bodyCrc32 = UtilAll.crc32(body);
        requestHeader.setBodyCrc32(bodyCrc32);
        /**
      *封装请求包头end
    **/
        //开启多线程到每个nameserver进行注册
        final CountDownLatch countDownLatch = new CountDownLatch(nameServerAddressList.size());
        for (final String namesrvAddr : nameServerAddressList) {
            brokerOuterExecutor.execute(new Runnable() {
                @Override
                public void run() {
                    try {
                        //实际进行注册方法
                        RegisterBrokerResult result = registerBroker(namesrvAddr,oneway, timeoutMills,requestHeader,body);
                        if (result != null) {
                            //封装nameserver返回的信息
                            registerBrokerResultList.add(result);
                        }
​
                        log.info("register broker[{}]to name server {} OK", brokerId, namesrvAddr);
                    } catch (Exception e) {
                        log.warn("registerBroker Exception, {}", namesrvAddr, e);
                    } finally {
                        countDownLatch.countDown();
                    }
                }
            });
        }
​
        try {
            countDownLatch.await(timeoutMills, TimeUnit.MILLISECONDS);
        } catch (InterruptedException e) {
        }
    }
​
    return registerBrokerResultList;
}