我有一个有两个节点的cassandra集群。。我已经设置了spark作业来查询这个cassandra集群，它有3651568个密钥。

import com.datastax.spark.connector.rdd.ReadConf
import org.apache.spark.sql.cassandra
import org.apache.spark.sql.SparkSession

val conf = new SparkConf(true).set("spark.cassandra.connection.host", "hostname)
val sc = new SparkContext(conf)

val spark = SparkSession.builder().master("local").appName("Spark_Cassandra").config("spark.cassandra.connection.host", "hostname").getOrCreate()
val studentsDF = spark.read.cassandraFormat("keyspacename", "tablename").options(ReadConf.SplitSizeInMBParam.option(32)).load()
studentsDF.show(1000)

我可以查询前1000行，但我找不到一种方法来读取 1001th 行到第2000行，这样我就可以使用spark job从cassandra表中批量读取数据。
根据推荐，我开始使用java驱动程序

下面是完整的解释

我必须使用datastax java驱动程序从cassandra数据库进行查询。。我使用的是datastax java驱动程序版本 cassandra-java-driver-3.5.1 和apache cassandra版本 apache-cassandra-3.0.9 我试着通过安装jar来解决依赖性我还检查了yaml文件种子、listen\u地址、rpc\u地址都指向我的主机并且start\u native\u transport设置为true这里是我的java代码，用于建立到cassandra数据库的连接

import java.net.InetAddress;
  import com.datastax.driver.core.Metadata;
  import java.net.UnknownHostException;
  import com.datastax.driver.core.Cluster;
  import com.datastax.driver.core.Cluster.Builder;
  import com.datastax.driver.core.Session;
  import com.datastax.driver.core.ResultSet;
  import com.datastax.driver.core.Row;
public class Started {
    public void connect()
    {
     try
       {
         Cluster cluster;
         Session session;
         cluster = Cluster.builder().addContactPoints("***.***.*.*").build();
       cluster.getConfiguration().getSocketOptions().setReadTimeoutMillis(2000);
         System.out.println("Connected to cluster:");
         session= cluster.connect("demo");
         Row row = session.execute("SELECT ename FROM demo.emp").one();
         System.out.println(row.getString("ename"));
         cluster.close();
        }
          catch (Exception e) {
              e.printStackTrace();
              }
           }
    public static void main(String[] args)
     {
       Started st = new Started();
       st.connect();
       }
          }

`
我在cassandra集群中只有一个节点，它正在运行。我也可以在9042端口连接到它。。到目前为止还不错，但当我运行我的java程序，我得到这个错误或异常消息。。。

Connected to cluster:
`

com.datastax.driver.core.exceptions.NoHostAvailableException: All host(s) tried for query failed (tried: /***.***.*.*:9042 (com.datastax.driver.core.exceptions.TransportException: [/***.***.*.*:9042] Cannot connect))
            at com.datastax.driver.core.ControlConnection.reconnectInternal(ControlConnection.java:232)
            at com.datastax.driver.core.ControlConnection.connect(ControlConnection.java:79)
            at com.datastax.driver.core.Cluster$Manager.negotiateProtocolVersionAndConnect(Cluster.java:1631)
            at com.datastax.driver.core.Cluster$Manager.init(Cluster.java:1549)
            at com.datastax.driver.core.Cluster.init(Cluster.java:160)
            at com.datastax.driver.core.Cluster.connectAsync(Cluster.java:342)
            at com.datastax.driver.core.Cluster.connect(Cluster.java:292)
            at Started.connect(Started.java:22)
            at Started.main(Started.java:34)

`

谁能帮帮我！！