怎么获取kafka topic存储数据的元数据信息，给出对应的java实现代码

可以使用 Kafka Java API 中的 AdminClient 类来获取 Kafka topic 存储数据的元数据信息。具体实现代码如下：

import java.util.Properties;
import java.util.concurrent.ExecutionException;
import org.apache.kafka.clients.admin.AdminClient;
import org.apache.kafka.clients.admin.DescribeTopicsResult;
import org.apache.kafka.clients.admin.TopicDescription;
import org.apache.kafka.common.KafkaFuture;
import org.apache.kafka.common.Node;
import org.apache.kafka.common.TopicPartitionInfo;

public class KafkaTopicMetadata {
    public static void main(String[] args) throws InterruptedException, ExecutionException {
        Properties props = new Properties();
        props.setProperty("bootstrap.servers", "localhost:9092");
        try (AdminClient adminClient = AdminClient.create(props)) {
            String topicName = "test-topic";
            DescribeTopicsResult describeTopicsResult = adminClient.describeTopics(Collections.singleton(topicName));
            KafkaFuture<Map<String, TopicDescription>> kafkaFuture = describeTopicsResult.all();
            Map<String, TopicDescription> topicDescriptionMap = kafkaFuture.get();
            TopicDescription topicDescription = topicDescriptionMap.get(topicName);
            List<TopicPartitionInfo> topicPartitionInfoList = topicDescription.partitions();
            System.out.println("Topic: " + topicName);
            System.out.println("Partitions: " + topicPartitionInfoList.size());
            for (TopicPartitionInfo topicPartitionInfo : topicPartitionInfoList) {
                Node leader = topicPartitionInfo.leader();
                List<Node> replicas = topicPartitionInfo.replicas();
                List<Node> isr = topicPartitionInfo.isr();
                System.out.println("Partition: " + topicPartitionInfo.partition());
                System.out.println("Leader: " + leader.host() + ":" + leader.port());
                System.out.println("Replicas: " + replicas);
                System.out.println("Isr: " + isr);
            }
        }
    }
}

以上代码中，我们首先创建一个 AdminClient 对象，然后调用其 describeTopics 方法获取指定 topic 的元数据信息。接着，我们从返回的 Map 中取出对应的 TopicDescription 对象，进而获取其包含的 Partition 信息。最后，我们遍历 Partition 信息，获取各个 Partition 的 Leader、Replicas 和 Isr 等信息。