RocketMq消费者拉取消息服务PullMessageService

@Override
public void run() {
    log.info(this.getServiceName() + " service started");

    while (!this.isStopped()) {
        try {
            //从请求队列里获取一个请求
            PullRequest pullRequest = this.pullRequestQueue.take();
            if (pullRequest != null) {
                //拉取数据
                this.pullMessage(pullRequest);
            }
        } catch (InterruptedException e) {
        } catch (Exception e) {
            log.error("Pull Message Service Run Method exception", e);
        }
    }

    log.info(this.getServiceName() + " service end");
}

PullMessageService#pullMessage

private void pullMessage(final PullRequest pullRequest) {
    //根据组名获取对应的消费者 一个mqClientInstance里一个consumerGroup只有一个消费者对应
    final MQConsumerInner consumer = this.mQClientFactory.selectConsumer(pullRequest.getConsumerGroup());
    if (consumer != null) {
        DefaultMQPushConsumerImpl impl = (DefaultMQPushConsumerImpl) consumer;
        //实际是根据组名获取对应的消费者来发起消息拉取
        impl.pullMessage(pullRequest);
    } else {
        log.warn("No matched consumer for the PullRequest {}, drop it", pullRequest);
    }
}

DefaultMQPushConsumerImpl#pullMessage