| /* |
| * 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 |
| * |
| * https://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.avro.hadoop.io; |
| |
| import java.util.Arrays; |
| |
| import org.apache.avro.Schema; |
| import org.apache.avro.generic.GenericRecord; |
| |
| /** |
| * A helper object for working with the Avro generic records that are used to |
| * store key/value pairs in an Avro container file. |
| * |
| * @param <K> The java type for the key. |
| * @param <V> The java type for the value. |
| */ |
| public class AvroKeyValue<K, V> { |
| /** The name of the key value pair generic record. */ |
| public static final String KEY_VALUE_PAIR_RECORD_NAME = "KeyValuePair"; |
| |
| /** The namespace of the key value pair generic record. */ |
| public static final String KEY_VALUE_PAIR_RECORD_NAMESPACE = "org.apache.avro.mapreduce"; |
| |
| /** The name of the generic record field containing the key. */ |
| public static final String KEY_FIELD = "key"; |
| |
| /** The name of the generic record field containing the value. */ |
| public static final String VALUE_FIELD = "value"; |
| |
| /** The key/value generic record wrapped by this class. */ |
| private final GenericRecord mKeyValueRecord; |
| |
| /** |
| * Wraps a GenericRecord that is a key value pair. |
| */ |
| public AvroKeyValue(GenericRecord keyValueRecord) { |
| mKeyValueRecord = keyValueRecord; |
| } |
| |
| /** |
| * Gets the wrapped key/value GenericRecord. |
| * |
| * @return The key/value Avro generic record. |
| */ |
| public GenericRecord get() { |
| return mKeyValueRecord; |
| } |
| |
| /** |
| * Read the key. |
| * |
| * @return The key from the key/value generic record. |
| */ |
| @SuppressWarnings("unchecked") |
| public K getKey() { |
| return (K) mKeyValueRecord.get(KEY_FIELD); |
| } |
| |
| /** |
| * Read the value. |
| * |
| * @return The value from the key/value generic record. |
| */ |
| @SuppressWarnings("unchecked") |
| public V getValue() { |
| return (V) mKeyValueRecord.get(VALUE_FIELD); |
| } |
| |
| /** |
| * Sets the key. |
| * |
| * @param key The key. |
| */ |
| public void setKey(K key) { |
| mKeyValueRecord.put(KEY_FIELD, key); |
| } |
| |
| /** |
| * Sets the value. |
| * |
| * @param value The value. |
| */ |
| public void setValue(V value) { |
| mKeyValueRecord.put(VALUE_FIELD, value); |
| } |
| |
| /** |
| * Creates a KeyValuePair generic record schema. |
| * |
| * @return A schema for a generic record with two fields: 'key' and 'value'. |
| */ |
| public static Schema getSchema(Schema keySchema, Schema valueSchema) { |
| Schema schema = Schema.createRecord(KEY_VALUE_PAIR_RECORD_NAME, "A key/value pair", KEY_VALUE_PAIR_RECORD_NAMESPACE, |
| false); |
| schema.setFields(Arrays.asList(new Schema.Field(KEY_FIELD, keySchema, "The key", null), |
| new Schema.Field(VALUE_FIELD, valueSchema, "The value", null))); |
| return schema; |
| } |
| |
| /** |
| * A wrapper for iterators over GenericRecords that are known to be KeyValue |
| * records. |
| * |
| * @param <K> The key type. |
| * @param <V> The value type. |
| */ |
| public static class Iterator<K, V> implements java.util.Iterator<AvroKeyValue<K, V>> { |
| /** The wrapped iterator. */ |
| private final java.util.Iterator<? extends GenericRecord> mGenericIterator; |
| |
| /** |
| * Constructs an iterator over key-value map entries out of a generic iterator. |
| * |
| * @param genericIterator An iterator over some generic record entries. |
| */ |
| public Iterator(java.util.Iterator<? extends GenericRecord> genericIterator) { |
| mGenericIterator = genericIterator; |
| } |
| |
| /** {@inheritDoc} */ |
| @Override |
| public boolean hasNext() { |
| return mGenericIterator.hasNext(); |
| } |
| |
| /** {@inheritDoc} */ |
| @Override |
| public AvroKeyValue<K, V> next() { |
| GenericRecord genericRecord = mGenericIterator.next(); |
| if (null == genericRecord) { |
| return null; |
| } |
| return new AvroKeyValue<>(genericRecord); |
| } |
| |
| /** {@inheritDoc} */ |
| @Override |
| public void remove() { |
| mGenericIterator.remove(); |
| } |
| } |
| } |