如何在Spark Kafka Connector中获取对象的JavaDStream？

import org.apache.spark.SparkConf;
import org.apache.spark.streaming.Durations;
import org.apache.spark.streaming.api.java.JavaDStream;
import org.apache.spark.streaming.api.java.JavaStreamingContext;
import org.apache.spark.streaming.kafka.KafkaUtils;
import kafka.serializer.StringDecoder;

public class SparkKafkaConnectorExample {
    public static void main(String[] args) throws InterruptedException {
        // 创建Spark配置
        SparkConf conf = new SparkConf().setAppName("SparkKafkaConnectorExample").setMaster("local[*]");

        // 创建StreamingContext
        JavaStreamingContext jssc = new JavaStreamingContext(conf, Durations.seconds(5));

        // 设置Kafka参数
        Map<String, String> kafkaParams = new HashMap<>();
        kafkaParams.put("bootstrap.servers", "localhost:9092");
        kafkaParams.put("group.id", "spark-kafka-example");

        // 设置要订阅的主题
        Set<String> topics = Collections.singleton("my-topic");

        // 创建Kafka输入DStream
        JavaDStream<String> kafkaStream = KafkaUtils.createDirectStream(
                jssc,
                String.class,
                String.class,
                StringDecoder.class,
                StringDecoder.class,
                kafkaParams,
                topics
        ).map(tuple -> tuple._2()); // 获取消息的值部分作为JavaDStream

        // 在这里可以对kafkaStream进行进一步处理，如转换为Java对象等

        // 启动StreamingContext
        jssc.start();
        jssc.awaitTermination();
    }
}