flink-connectors/flink-connector-kafka-base/src/main/java/org/apache/flink/streaming/connectors/kafka/KafkaAvroTableSource.java

/*
 * 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,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.streaming.connectors.kafka;

import org.apache.flink.annotation.Internal;
import org.apache.flink.api.common.serialization.DeserializationSchema;
import org.apache.flink.formats.avro.AvroRowDeserializationSchema;
import org.apache.flink.table.api.TableSchema;
import org.apache.flink.table.descriptors.ConnectorDescriptor;
import org.apache.flink.table.plan.stats.TableStats;
import org.apache.flink.table.sources.StreamTableSource;

import org.apache.avro.specific.SpecificRecord;
import org.apache.avro.specific.SpecificRecordBase;

import java.util.Map;
import java.util.Properties;

/**
 * A version-agnostic Kafka Avro {@link StreamTableSource}.
 *
 * <p>The version-specific Kafka consumers need to extend this class and
 * override {@link #createKafkaConsumer(String, Properties, DeserializationSchema)}}.
 *
 * @deprecated Use the {@link org.apache.flink.table.descriptors.Kafka} descriptor together
 *             with descriptors for schema and format instead. Descriptors allow for
 *             implementation-agnostic definition of tables. See also
 *             {@link org.apache.flink.table.api.TableEnvironment#connect(ConnectorDescriptor)}.
 */
@Deprecated
@Internal
public abstract class KafkaAvroTableSource extends KafkaTableSource {

	/**
	 * Creates a generic Kafka Avro {@link StreamTableSource} using a given {@link SpecificRecord}.
	 *
	 * @param topic            Kafka topic to consume.
	 * @param properties       Properties for the Kafka consumer.
	 * @param schema           Schema of the produced table.
	 * @param avroRecordClass  Class of the Avro record that is read from the Kafka topic.
	 * @deprecated Use the {@link org.apache.flink.table.descriptors.Kafka} descriptor together
	 *             with descriptors for schema and format instead. Descriptors allow for
	 *             implementation-agnostic definition of tables. See also
	 *             {@link org.apache.flink.table.api.TableEnvironment#connect(ConnectorDescriptor)}.
	 */
	@Deprecated
	protected KafkaAvroTableSource(
		String topic,
		Properties properties,
		TableSchema schema,
		Class<? extends SpecificRecordBase> avroRecordClass) {

		super(
			schema,
			topic,
			properties,
			new AvroRowDeserializationSchema(avroRecordClass));
	}

	@Override
	public String explainSource() {
		return "KafkaAvroTableSource";
	}

	@Override
	public TableStats getTableStats() {
		return null;
	}

	//////// HELPER METHODS

	/**
	 * Abstract builder for a {@link KafkaAvroTableSource} to be extended by builders of subclasses of
	 * KafkaAvroTableSource.
	 *
	 * @param <T> Type of the KafkaAvroTableSource produced by the builder.
	 * @param <B> Type of the KafkaAvroTableSource.Builder subclass.
	 *
	 * @deprecated Use the {@link org.apache.flink.table.descriptors.Kafka} descriptor together
	 *             with descriptors for schema and format instead. Descriptors allow for
	 *             implementation-agnostic definition of tables. See also
	 *             {@link org.apache.flink.table.api.TableEnvironment#connect(ConnectorDescriptor)}.
	 */
	@Deprecated
	protected abstract static class Builder<T extends KafkaAvroTableSource, B extends Builder>
		extends KafkaTableSource.Builder<T, B> {

		private Class<? extends SpecificRecordBase> avroClass;

		private Map<String, String> fieldMapping;

		/**
		 * Sets the class of the Avro records that are read from the Kafka topic.
		 *
		 * @param avroClass The class of the Avro records that are read from the Kafka topic.
		 * @return The builder.
		 * @deprecated Use table descriptors instead of implementation-specific builders.
		 */
		@Deprecated
		public B forAvroRecordClass(Class<? extends SpecificRecordBase> avroClass) {
			this.avroClass = avroClass;
			return builder();
		}

		/**
		 * Sets a mapping from schema fields to fields of the produced Avro record.
		 *
		 * <p>A field mapping is required if the fields of produced tables should be named different than
		 * the fields of the Avro record.
		 * The key of the provided Map refers to the field of the table schema,
		 * the value to the field of the Avro record.</p>
		 *
		 * @param schemaToAvroMapping A mapping from schema fields to Avro fields.
		 * @return The builder.
		 * @deprecated Use table descriptors instead of implementation-specific builders.
		 */
		@Deprecated
		public B withTableToAvroMapping(Map<String, String> schemaToAvroMapping) {
			this.fieldMapping = schemaToAvroMapping;
			return builder();
		}

		/**
		 * Returns the configured Avro class.
		 *
		 * @return The configured Avro class.
		 * @deprecated Use table descriptors instead of implementation-specific builders.
		 */
		@Deprecated
		protected Class<? extends SpecificRecordBase> getAvroRecordClass() {
			return this.avroClass;
		}

		@Override
		protected void configureTableSource(T source) {
			super.configureTableSource(source);
			source.setFieldMapping(this.fieldMapping);
		}
	}
}