TimeWindowedSerializer.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.kafka.streams.kstream;

import org.apache.kafka.common.config.ConfigException;
import org.apache.kafka.common.serialization.Serde;
import org.apache.kafka.common.serialization.Serializer;
import org.apache.kafka.common.utils.Utils;
import org.apache.kafka.streams.StreamsConfig;
import org.apache.kafka.streams.kstream.internals.WindowedSerializer;
import org.apache.kafka.streams.state.internals.WindowKeySchema;

import java.util.Map;

/**
 *  The inner serde class can be specified by setting the property
 *  {@link StreamsConfig#DEFAULT_WINDOWED_KEY_SERDE_INNER_CLASS} or
 *  {@link StreamsConfig#DEFAULT_WINDOWED_VALUE_SERDE_INNER_CLASS}
 *  if the no-arg constructor is called and hence it is not passed during initialization.
 */
public class TimeWindowedSerializer<T> implements WindowedSerializer<T> {

    private Serializer<T> inner;

    // Default constructor needed by Kafka
    public TimeWindowedSerializer() {}

    public TimeWindowedSerializer(final Serializer<T> inner) {
        this.inner = inner;
    }

    @SuppressWarnings("unchecked")
    @Override
    public void configure(final Map<String, ?> configs, final boolean isKey) {
        if (inner == null) {
            final String propertyName = isKey ? StreamsConfig.DEFAULT_WINDOWED_KEY_SERDE_INNER_CLASS : StreamsConfig.DEFAULT_WINDOWED_VALUE_SERDE_INNER_CLASS;
            final String value = (String) configs.get(propertyName);
            try {
                inner = Serde.class.cast(Utils.newInstance(value, Serde.class)).serializer();
                inner.configure(configs, isKey);
            } catch (final ClassNotFoundException e) {
                throw new ConfigException(propertyName, value, "Serde class " + value + " could not be found.");
            }
        }
    }

    @Override
    public byte[] serialize(final String topic, final Windowed<T> data) {
        if (data == null)
            return null;

        return WindowKeySchema.toBinary(data, inner, topic);
    }

    @Override
    public void close() {
        inner.close();
    }

    @Override
    public byte[] serializeBaseKey(final String topic, final Windowed<T> data) {
        return inner.serialize(topic, data.key());
    }

    // Only for testing
    Serializer<T> innerSerializer() {
        return inner;
    }
}