private void testBatchMessages() {
        List<Message> msgs = new ArrayList<Message>();
        for (int i = 0; i < 10; i++) {
            msgs.add(MessageBuilder.withPayload("Hello RocketMQ Batch Msg#" + i).
                setHeader(RocketMQHeaders.KEYS, "KEY_" + i).build());
        }

        SendResult sr = rocketMQTemplate.syncSend(springTopic, msgs, 60000);

        System.out.printf("--- Batch messages send result :" + sr);
    }
Producer, using RocketMQTemplate sends a variety of messages
rocketmq-spring-boot-samples/rocketmq-produce-demo/src/main/java/org/apache/rocketmq/samples/springboot/ProducerApplication.java