parquet-hadoop/src/main/java/org/apache/parquet/hadoop/example/GroupReadSupport.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
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package org.apache.parquet.hadoop.example;

import java.util.Map;

import org.apache.hadoop.conf.Configuration;

import org.apache.parquet.example.data.Group;
import org.apache.parquet.example.data.simple.convert.GroupRecordConverter;
import org.apache.parquet.hadoop.api.InitContext;
import org.apache.parquet.hadoop.api.ReadSupport;
import org.apache.parquet.io.api.RecordMaterializer;
import org.apache.parquet.schema.MessageType;

public class GroupReadSupport extends ReadSupport<Group> {

  @Override
  public ReadContext init(InitContext context) {
    String partialSchemaString = context.getConfiguration().get(ReadSupport.PARQUET_READ_SCHEMA);
    MessageType requestedProjection = getSchemaForRead(context.getFileSchema(), partialSchemaString);
    return new ReadContext(requestedProjection);
  }

  @Override
  public RecordMaterializer<Group> prepareForRead(Configuration configuration,
      Map<String, String> keyValueMetaData, MessageType fileSchema,
      org.apache.parquet.hadoop.api.ReadSupport.ReadContext readContext) {
    return new GroupRecordConverter(readContext.getRequestedSchema());
  }

}