kafka KeyValueMapper 源码
kafka KeyValueMapper 代码
文件路径：/streams/src/main/java/org/apache/kafka/streams/kstream/KeyValueMapper.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.streams.KeyValue;
/**
* The {@code KeyValueMapper} interface for mapping a {@link KeyValue key-value pair} to a new value of arbitrary type.
* For example, it can be used to
* <ul>
* <li>map from an input {@link KeyValue} pair to an output {@link KeyValue} pair with different key and/or value type
* (for this case output type {@code VR == }{@link KeyValue KeyValue<NewKeyType,NewValueType>})</li>
* <li>map from an input record to a new key (with arbitrary key type as specified by {@code VR})</li>
* </ul>
* This is a stateless record-by-record operation, i.e, {@link #apply(Object, Object)} is invoked individually for each
* record of a stream (cf. {@link Transformer} for stateful record transformation).
* {@code KeyValueMapper} is a generalization of {@link ValueMapper}.
*
* @param <K> key type
* @param <V> value type
* @param <VR> mapped value type
* @see ValueMapper
* @see Transformer
* @see KStream#map(KeyValueMapper)
* @see KStream#flatMap(KeyValueMapper)
* @see KStream#selectKey(KeyValueMapper)
* @see KStream#groupBy(KeyValueMapper)
* @see KStream#groupBy(KeyValueMapper, Grouped)
* @see KTable#groupBy(KeyValueMapper)
* @see KTable#groupBy(KeyValueMapper, Grouped)
* @see KTable#toStream(KeyValueMapper)
*/
public interface KeyValueMapper<K, V, VR> {
/**
* Map a record with the given key and value to a new value.
*
* @param key the key of the record
* @param value the value of the record
* @return the new value
*/
VR apply(final K key, final V value);
}
相关信息
相关文章
0
赞
热门推荐
-
2、 - 优质文章
-
3、 gate.io
-
7、 golang
-
9、 openharmony
-
10、 Vue中input框自动聚焦