org.apache.avro.hadoop.io

Class AvroDeserializer<T extends AvroWrapper<D>,D>

java.lang.Object

org.apache.avro.hadoop.io.AvroDeserializer<T,D>

Type Parameters:

T - The type of Avro wrapper.

D - The Java type of the Avro data being wrapped.

All Implemented Interfaces:

org.apache.hadoop.io.serializer.Deserializer<T>

Direct Known Subclasses:

AvroKeyDeserializer, AvroValueDeserializer

public abstract class AvroDeserializer<T extends AvroWrapper<D>,D>
extends Object
implements org.apache.hadoop.io.serializer.Deserializer<T>

Deserializes AvroWrapper objects within Hadoop.

Keys and values containing Avro tyeps are more efficiently serialized outside of the WritableSerialization model, so they are wrapper in AvroWrapper objects and deserialization is handled by this class.

MapReduce jobs that use AvroWrapper objects as keys or values need to be configured with org.apache.avro.io.AvroSerialization. Use AvroJob to help with Job configuration.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AvroDeserializer(Schema writerSchema, Schema readerSchema, ClassLoader classLoader) Constructor.
protected	AvroDeserializer(Schema writerSchema, Schema readerSchema, DatumReader<D> datumReader) Constructor.

Method Summary

Methods

Modifier and Type	Method and Description
void	close()
protected abstract T	createAvroWrapper() Creates a new empty T (extends AvroWrapper) instance.
T	deserialize(T avroWrapperToReuse)
Schema	getReaderSchema() Gets the reader schema used for deserializing.
Schema	getWriterSchema() Gets the writer schema used for deserializing.
void	open(InputStream inputStream)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

AvroDeserializer

protected AvroDeserializer(Schema writerSchema,
                Schema readerSchema,
                ClassLoader classLoader)

Constructor.

Parameters:

writerSchema - The Avro writer schema for the data to deserialize.

readerSchema - The Avro reader schema for the data to deserialize (may be null).

AvroDeserializer

protected AvroDeserializer(Schema writerSchema,
                Schema readerSchema,
                DatumReader<D> datumReader)

Constructor.

Parameters:

writerSchema - The Avro writer schema for the data to deserialize.

readerSchema - The Avro reader schema for the data to deserialize (may be null).

datumReader - The Avro datum reader to use for deserialization.

Method Detail

getWriterSchema

public Schema getWriterSchema()

Gets the writer schema used for deserializing.

Returns:

The writer schema;

getReaderSchema

public Schema getReaderSchema()

Gets the reader schema used for deserializing.

Returns:

The reader schema.

open

public void open(InputStream inputStream)
          throws IOException

Specified by:

open in interface org.apache.hadoop.io.serializer.Deserializer<T extends AvroWrapper<D>>

Throws:

IOException

deserialize

public T deserialize(T avroWrapperToReuse)
                                     throws IOException

Specified by:

deserialize in interface org.apache.hadoop.io.serializer.Deserializer<T extends AvroWrapper<D>>

Throws:

IOException

close

public void close()
           throws IOException

Specified by:

close in interface org.apache.hadoop.io.serializer.Deserializer<T extends AvroWrapper<D>>

Throws:

IOException

createAvroWrapper

protected abstract T createAvroWrapper()

Creates a new empty T (extends AvroWrapper) instance.

Returns:

A new empty T instance.