AHeise commented on a change in pull request #16783: URL: https://github.com/apache/flink/pull/16783#discussion_r690484382
########## File path: flink-connectors/flink-connector-kafka/src/main/java/org/apache/flink/streaming/connectors/kafka/sink/KafkaRecordSerializationSchemaBuilder.java ########## @@ -0,0 +1,270 @@ +/* + * 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.sink; + +import org.apache.flink.api.common.serialization.SerializationSchema; +import org.apache.flink.streaming.connectors.kafka.partitioner.FlinkKafkaPartitioner; + +import org.apache.kafka.clients.producer.ProducerRecord; +import org.apache.kafka.common.Configurable; +import org.apache.kafka.common.serialization.Serializer; + +import javax.annotation.Nullable; + +import java.util.Map; +import java.util.OptionalInt; +import java.util.function.Function; + +import static org.apache.flink.util.Preconditions.checkNotNull; +import static org.apache.flink.util.Preconditions.checkState; + +/** + * Builder to construct {@link KafkaRecordSerializationSchema}. + * + * <p>This class should give a first entrypoint when trying to serialize elements to {@link + * ProducerRecord}. The following examples show some of the possibilities. + * + * <pre>Simple key-value serialization: + * {@code + * new KafkaRecordSerializationSchemaBuilder<String>("topic") + * .withKeySerializationSchema(new SimpleStringSchema()) + * .withValueSerializationSchema(new SimpleStringSchema()) + * .build() + * }</pre> + * + * <pre>Using Kafka's serialization stack: + * {@code + * new KafkaRecordSerializationSchemaBuilder<String>("topic") + * .withKeySerializer(StringSerializer.class) + * .withValueSerializer(StringSerializer.class) + * .build() + * }</pre> + * + * <pre>With custom partitioner: + * {@code + * new KafkaRecordSerializationSchemaBuilder<String>("topic") + * .withPartitioner(MY_FLINK_PARTITIONER) + * .withKeySerializationSchema(StringSerializer.class) + * .build() + * }</pre> + * + * <p>The different serialization methods for key and value are mutually exclusive thus i.e. it is + * not possible to use {@link #withKeySerializationSchema(SerializationSchema)} and {@link + * #withKeySerializer(Class)} on the same builder instance. + * + * <p>It is necessary to configure exactly one serialization method for the value. + * + * @param <IN> type of records to be serialized + * @see KafkaRecordSerializationSchema#builder(String) + */ +public class KafkaRecordSerializationSchemaBuilder<IN> { + + @Nullable private final String topic; + @Nullable private final Function<IN, String> topicSelector; + @Nullable private FlinkKafkaPartitioner<IN> partitioner; + @Nullable private SerializationSchema<IN> keySerializationSchema; + + private SerializationSchema<IN> valueSerializationSchema; Review comment: Yes, `@Nullable` is meant for "compiler" (= IDE) to warn you about nullability issues similar to Kotlin. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: issues-unsubscr...@flink.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
