Java tutorial
/* * 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 * <p> * http://www.apache.org/licenses/LICENSE-2.0 * <p> * 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.storm.sql.runtime.serde.csv; import java.io.IOException; import java.io.Serializable; import java.io.StringWriter; import java.nio.ByteBuffer; import java.nio.charset.StandardCharsets; import java.util.List; import org.apache.commons.csv.CSVFormat; import org.apache.commons.csv.CSVPrinter; import org.apache.storm.sql.runtime.IOutputSerializer; /** * CsvSerializer uses the standard RFC4180 CSV Parser * One of the difference from Tsv format is that fields with embedded commas will be quoted. * eg: a,"b,c",d is allowed. * * @see <a href="https://tools.ietf.org/html/rfc4180">RFC4180</a> */ public class CsvSerializer implements IOutputSerializer, Serializable { private final List<String> fields; //reserved for future public CsvSerializer(List<String> fields) { this.fields = fields; } @Override public ByteBuffer write(List<Object> data, ByteBuffer buffer) { try { StringWriter writer = new StringWriter(); CSVPrinter printer = new CSVPrinter(writer, CSVFormat.RFC4180); for (Object o : data) { printer.print(o); } //since using StringWriter, we do not need to close it. return ByteBuffer.wrap(writer.getBuffer().toString().getBytes(StandardCharsets.UTF_8)); } catch (IOException e) { throw new RuntimeException(e); } } }