下面是一个使用Java编写的示例代码，演示了如何使用Apache Kafka来创建一个包含3个分区和3个消费者的消费者组，并且每个消费者都是多线程的。

import org.apache.kafka.clients.consumer.ConsumerConfig;
import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.apache.kafka.clients.consumer.ConsumerRecords;
import org.apache.kafka.clients.consumer.KafkaConsumer;

import java.util.Arrays;
import java.util.Properties;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class KafkaConsumerExample {

    private static final String TOPIC_NAME = "your_topic_name";
    private static final String BOOTSTRAP_SERVERS = "your_bootstrap_servers";

    public static void main(String[] args) {
        // 创建消费者配置
        Properties properties = new Properties();
        properties.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, BOOTSTRAP_SERVERS);
        properties.put(ConsumerConfig.GROUP_ID_CONFIG, "your_consumer_group_id");
        properties.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.StringDeserializer");
        properties.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.StringDeserializer");

        // 创建一个线程池
        ExecutorService executor = Executors.newFixedThreadPool(3);

        for (int i = 0; i < 3; i++) {
            // 创建一个消费者实例
            KafkaConsumer consumer = new KafkaConsumer<>(properties);

            // 订阅主题
            consumer.subscribe(Arrays.asList(TOPIC_NAME));

            // 创建一个消费者线程
            ConsumerThread consumerThread = new ConsumerThread(consumer);

            // 将消费者线程提交给线程池执行
            executor.submit(consumerThread);
        }

        // 关闭线程池
        executor.shutdown();
    }

    private static class ConsumerThread implements Runnable {
        private KafkaConsumer consumer;

        public ConsumerThread(KafkaConsumer consumer) {
            this.consumer = consumer;
        }

        @Override
        public void run() {
            try {
                while (true) {
                    // 从Kafka拉取消息
                    ConsumerRecords records = consumer.poll(100);

                    for (ConsumerRecord record : records) {
                        // 处理接收到的消息
                        System.out.println("Thread: " + Thread.currentThread().getName() +
                                ", Partition: " + record.partition() +
                                ", Offset: " + record.offset() +
                                ", Value: " + record.value());
                    }
                }
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                consumer.close();
            }
        }
    }
}

请记得替换代码中的 your_topic_name 和 your_bootstrap_servers 为你自己的实际值。这个示例代码会创建一个线程池，其中每个线程都是一个Kafka消费者，每个消费者都会以多线程的方式消费来自3个分区的消息。