kafka PrintForeachAction 源码
kafka PrintForeachAction 代码
文件路径：/streams/src/main/java/org/apache/kafka/streams/kstream/internals/PrintForeachAction.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.internals;
import org.apache.kafka.streams.kstream.ForeachAction;
import org.apache.kafka.streams.kstream.KeyValueMapper;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.nio.charset.StandardCharsets;
public class PrintForeachAction<K, V> implements ForeachAction<K, V> {
private final String label;
private final PrintWriter printWriter;
private final boolean closable;
private final KeyValueMapper<? super K, ? super V, String> mapper;
/**
* Print customized output with given writer. The {@link OutputStream} can be {@link System#out} or the others.
*
* @param outputStream The output stream to write to.
* @param mapper The mapper which can allow user to customize output will be printed.
* @param label The given name will be printed.
*/
PrintForeachAction(final OutputStream outputStream,
final KeyValueMapper<? super K, ? super V, String> mapper,
final String label) {
this.printWriter = new PrintWriter(new OutputStreamWriter(outputStream, StandardCharsets.UTF_8));
this.closable = outputStream != System.out && outputStream != System.err;
this.mapper = mapper;
this.label = label;
}
@Override
public void apply(final K key, final V value) {
final String data = String.format("[%s]: %s", label, mapper.apply(key, value));
printWriter.println(data);
if (!closable) {
printWriter.flush();
}
}
public void close() {
if (closable) {
printWriter.close();
} else {
printWriter.flush();
}
}
}
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