private void getProducerListInfo(final HttpServletRequest req, StringBuilder sBuilder) {
        String producerId = req.getParameter("id");
        if (producerId != null) {
            ProducerInfo producer = master.getProducerHolder().getProducerInfo(producerId);
            if (producer != null) {
                sBuilder.append(producer.toString());
            } else {
                sBuilder.append("No such producer!");
            }
        } else {
            String topic = req.getParameter("topic");
            if (topic != null) {
                TopicPSInfoManager topicPSInfoManager =
                        master.getTopicPSInfoManager();
                Set<String> producerSet =
                        topicPSInfoManager.getTopicPubInfo(topic);
                if (producerSet != null && !producerSet.isEmpty()) {
                    int index = 1;
                    for (String producer : producerSet) {
                        sBuilder.append(index).append(". ").append(producer).append("\n");
                        index++;
                    }
                }
            }
        }
    }
Get producer list info

@param req
@param sBuilder
@return
inlong-tubemq/tubemq-server/src/main/java/org/apache/inlong/tubemq/server/master/web/action/screen/Master.java