java - 无法连接到 Cassandra - Cassandra Datastax 驱动程序 3.6 中的 Guava 兼容性问题

Question

我正在使用 Cassandra 驱动程序 3.6.0 和 Guava 19.0；我得到以下异常:

[main] INFO com.datastax.driver.core - DataStax Java driver 3.6.0 for Apache Cassandra
[main] INFO com.datastax.driver.core.GuavaCompatibility - Detected Guava >= 19 in the classpath, using modern compatibility layer 
[main] INFO com.datastax.driver.core.ClockFactory - Using native clock to generate timestamps.
Exception in thread "main" com.datastax.driver.core.exceptions.NoHostAvailableException: All host(s) tried for query failed (tried: localhost/127.0.0.1:9042 
(com.datastax.driver.core.exceptions.TransportException: [localhost/127.0.0.1:9042] Cannot connect), localhost/0:0:0:0:0:0:0:1:9042 
(com.datastax.driver.core.exceptions.TransportException: [localhost/0:0:0:0:0:0:0:1:9042] Cannot connect))
  at com.datastax.driver.core.ControlConnection.reconnectInternal(ControlConnection.java:268)

我将 Cassandra Core 驱动程序从 20 降级到 19；当我从客户端代码连接到集群时，我仍然遇到上述问题。

pom.xml 片段

        <dependency>
            <groupId>com.datastax.cassandra</groupId>
            <artifactId>cassandra-driver-core</artifactId>
            <version>3.6.0</version>
        </dependency>
        <dependency>
            <groupId>com.datastax.cassandra</groupId>
            <artifactId>cassandra-driver-mapping</artifactId>
            <version>3.6.0</version>
        </dependency>
        <dependency>
            <groupId>com.google.guava</groupId>
            <artifactId>guava</artifactId>
            <version>19.0</version>
        </dependency>

Java 驱动程序

package com.cassandra.javaConnect;

import java.time.Instant;
import java.time.ZoneId;
import java.util.Date;
import java.util.UUID;

import com.datastax.driver.core.BoundStatement;
import com.datastax.driver.core.Cluster;
import com.datastax.driver.core.PreparedStatement;
import com.datastax.driver.core.ResultSet;
import com.datastax.driver.core.Session;

public class CassandraV3Tutorial {

    private final static String KEYSPACE_NAME = "example_keyspace";
    private final static String REPLICATION_STRATEGY = "SimpleStrategy";
    private final static int REPLICATION_FACTOR = 1;
    private final static String TABLE_NAME = "example_table";

    public static void main(String[] args) {

        // Setup a cluster to your local instance of Cassandra
        Cluster cluster = Cluster.builder()
                .addContactPoint("localhost")
                .withPort(9042)
                .build();

        // Create a session to communicate with Cassandra
        Session session = cluster.connect();

        // Create a new Keyspace (database) in Cassandra
        String createKeyspace = String.format(
                "CREATE KEYSPACE IF NOT EXISTS %s WITH replication = " +
                        "{'class':'%s','replication_factor':%s};",
                KEYSPACE_NAME,
                REPLICATION_STRATEGY,
                REPLICATION_FACTOR
        );
        session.execute(createKeyspace);

        // Create a new table in our Keyspace
        String createTable = String.format(
                "CREATE TABLE IF NOT EXISTS %s.%s " + "" +
                        "(id uuid, timestamp timestamp, value double, " +
                        "PRIMARY KEY (id, timestamp)) " +
                        "WITH CLUSTERING ORDER BY (timestamp ASC);",
                KEYSPACE_NAME,
                TABLE_NAME
        );
        session.execute(createTable);

        // Create an insert statement to add a new item to our table
        PreparedStatement insertPrepared = session.prepare(String.format(
                "INSERT INTO %s.%s (id, timestamp, value) values (?, ?, ?)",
                KEYSPACE_NAME,
                TABLE_NAME
        ));

        // Some example data to insert
        UUID id = UUID.fromString("1e4d26ed-922a-4bd2-85cb-6357b202eda8");
        Date timestamp = Date.from(Instant.parse("2018-01-01T01:01:01.000Z"));
        double value = 123.45;

        // Bind the data to the insert statement and execute it
        BoundStatement insertBound = insertPrepared.bind(id, timestamp, value);
        session.execute(insertBound);

        // Create a select statement to retrieve the item we just inserted
        PreparedStatement selectPrepared = session.prepare(String.format(
                "SELECT id, timestamp, value FROM %s.%s WHERE id = ?",
                KEYSPACE_NAME,
                TABLE_NAME));

        // Bind the id to the select statement and execute it
        BoundStatement selectBound = selectPrepared.bind(id);
        ResultSet resultSet = session.execute(selectBound);

        // Print the retrieved data
        resultSet.forEach(row -> System.out.println(
                String.format("Id: %s, Timestamp: %s, Value: %s",
                row.getUUID("id"),
                row.getTimestamp("timestamp").toInstant().atZone(ZoneId.of("UTC")),
                row.getDouble("value"))));

        // Close session and disconnect from cluster
        session.close();
        cluster.close();
    }
}

Answer 1

此错误并不意味着您的 Guava 版本错误。该消息是在 cassandra-driver-core-3.2.0 中引入的，请参阅 JAVA-1328和 JAVA-1435 。 INFO com.datastax.driver.core.GuavaCompatibility - 在类路径中检测到 Guava >= 19，使用现代兼容层 表示驱动程序检测到 Guava 19+ 并且它正在使用某些兼容层进行操作。您可以很好地使用 Guava 20，甚至任何更新的版本。

另一方面，您的错误意味着驱动程序无法在端口 9042 上连接到本地 Cassandra 实例。它要么未启动，要么在不同的端口上启动，或者某些软件(例如防火墙)阻止了它。请确保 cassandra 进程正在运行，并使用例如 netstat 来查看端口 9042 是否被 Cassandra 使用。