flink-connectors/flink-connector-cassandra/src/test/java/org/apache/flink/batch/connectors/cassandra/example/BatchPojoExample.java

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 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
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 * See the License for the specific language governing permissions and
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package org.apache.flink.batch.connectors.cassandra.example;

import org.apache.flink.api.java.DataSet;
import org.apache.flink.api.java.ExecutionEnvironment;
import org.apache.flink.batch.connectors.cassandra.CassandraPojoInputFormat;
import org.apache.flink.batch.connectors.cassandra.CassandraPojoOutputFormat;
import org.apache.flink.batch.connectors.cassandra.CustomCassandraAnnotatedPojo;
import org.apache.flink.streaming.connectors.cassandra.ClusterBuilder;

import com.datastax.driver.core.Cluster;
import com.datastax.driver.core.ConsistencyLevel;
import com.datastax.driver.mapping.Mapper;

import java.util.List;
import java.util.UUID;
import java.util.stream.Collectors;
import java.util.stream.IntStream;

/**
 * This is an example showing the to use the {@link CassandraPojoInputFormat}/{@link CassandraPojoOutputFormat} in the Batch API.
 *
 * <p>The example assumes that a table exists in a local cassandra database, according to the following queries:
 * CREATE KEYSPACE IF NOT EXISTS flink WITH replication = {'class': 'SimpleStrategy', 'replication_factor': '1'};
 * CREATE TABLE IF NOT EXISTS flink.batches (id text, counter int, batch_id int, PRIMARY KEY(id, counter, batchId));
 */
public class BatchPojoExample {
	private static final String SELECT_QUERY = "SELECT id, counter, batch_id FROM flink.batches;";

	public static void main(String[] args) throws Exception {

		ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
		env.setParallelism(1);

		List<CustomCassandraAnnotatedPojo> customCassandraAnnotatedPojos = IntStream.range(0, 20)
				.mapToObj(x -> new CustomCassandraAnnotatedPojo(UUID.randomUUID().toString(), x, 0))
				.collect(Collectors.toList());

		DataSet<CustomCassandraAnnotatedPojo> dataSet = env.fromCollection(customCassandraAnnotatedPojos);

		ClusterBuilder clusterBuilder = new ClusterBuilder() {
			private static final long serialVersionUID = -1754532803757154795L;

			@Override
			protected Cluster buildCluster(Cluster.Builder builder) {
				return builder.addContactPoints("127.0.0.1").build();
			}
		};

		dataSet.output(new CassandraPojoOutputFormat<>(clusterBuilder, CustomCassandraAnnotatedPojo.class, () -> new Mapper.Option[]{Mapper.Option.saveNullFields(true)}));

		env.execute("Write");

		/*
		 *	This is for the purpose of showing an example of creating a DataSet using CassandraPojoInputFormat.
		 */
		DataSet<CustomCassandraAnnotatedPojo> inputDS = env
			.createInput(new CassandraPojoInputFormat<>(
				SELECT_QUERY,
				clusterBuilder,
				CustomCassandraAnnotatedPojo.class,
				() -> new Mapper.Option[]{Mapper.Option.consistencyLevel(ConsistencyLevel.ANY)}
			));

		inputDS.print();
	}
}