Package org.apache.hadoop.io

Generic i/o code for use when reading and writing data to the network, to databases, and to files.

See: Description

Interface Summary

Interface	Description
ByteBufferPool
Closeable	Deprecated use java.io.Closeable
MapFile.Reader.Option
MapFile.Writer.Option
RawComparator<T>	A Comparator that operates directly on byte representations of objects.
ReadaheadPool.ReadaheadRequest	An outstanding readahead request that has been submitted to the pool.
SequenceFile.Reader.Option	A tag interface for all of the Reader options
SequenceFile.Sorter.RawKeyValueIterator	The interface to iterate over raw keys/values of SequenceFiles.
SequenceFile.ValueBytes	The interface to 'raw' values of SequenceFiles.
SequenceFile.Writer.Option
Stringifier<T>	Stringifier interface offers two methods to convert an object to a string representation and restore the object given its string representation.
Writable	A serializable object which implements a simple, efficient, serialization protocol, based on DataInput and DataOutput.
WritableComparable<T>	A Writable which is also Comparable.
WritableFactory	A factory for a class of Writable.

Class Summary

Class	Description
AbstractMapWritable	Abstract base class for MapWritable and SortedMapWritable Unlike org.apache.nutch.crawl.MapWritable, this class allows creation of MapWritable<Writable, MapWritable> so the CLASS_TO_ID and ID_TO_CLASS maps travel with the class instead of being static.
ArrayFile	A dense file-based mapping from integers to values.
ArrayFile.Reader	Provide access to an existing array file.
ArrayFile.Writer	Write a new array file.
ArrayPrimitiveWritable	This is a wrapper class.
ArrayWritable	A Writable for arrays containing instances of a class.
BinaryComparable	Interface supported by WritableComparable types supporting ordering/permutation by a representative set of bytes.
BloomMapFile	This class extends MapFile and provides very much the same functionality.
BloomMapFile.Reader
BloomMapFile.Writer
BooleanWritable	A WritableComparable for booleans.
BooleanWritable.Comparator	A Comparator optimized for BooleanWritable.
BytesWritable	A byte sequence that is usable as a key or value.
BytesWritable.Comparator	A Comparator optimized for BytesWritable.
ByteWritable	A WritableComparable for a single byte.
ByteWritable.Comparator	A Comparator optimized for ByteWritable.
CompressedWritable	A base-class for Writables which store themselves compressed and lazily inflate on field access.
DataInputByteBuffer
DataOutputByteBuffer
DataOutputOutputStream	OutputStream implementation that wraps a DataOutput.
DefaultStringifier<T>	DefaultStringifier is the default implementation of the Stringifier interface which stringifies the objects using base64 encoding of the serialized version of the objects.
DoubleWritable	Writable for Double values.
DoubleWritable.Comparator	A Comparator optimized for DoubleWritable.
ElasticByteBufferPool	This is a simple ByteBufferPool which just creates ByteBuffers as needed.
EnumSetWritable<E extends Enum<E>>	A Writable wrapper for EnumSet.
FloatWritable	A WritableComparable for floats.
FloatWritable.Comparator	A Comparator optimized for FloatWritable.
GenericWritable	A wrapper for Writable instances.
IntWritable	A WritableComparable for ints.
IntWritable.Comparator	A Comparator optimized for IntWritable.
IOUtils	An utility class for I/O related functionality.
IOUtils.NullOutputStream	The /dev/null of OutputStreams.
LongWritable	A WritableComparable for longs.
LongWritable.Comparator	A Comparator optimized for LongWritable.
LongWritable.DecreasingComparator	A decreasing Comparator optimized for LongWritable.
MapFile	A file-based map from keys to values.
MapFile.Merger	Class to merge multiple MapFiles of same Key and Value types to one MapFile
MapFile.Reader	Provide access to an existing map.
MapFile.Writer	Writes a new map.
MapWritable	A Writable Map.
MD5Hash	A Writable for MD5 hash values.
MD5Hash.Comparator	A WritableComparator optimized for MD5Hash keys.
MultipleIOException.Builder	Build an IOException using MultipleIOException if there are more than one.
NullWritable	Singleton Writable with no data.
NullWritable.Comparator	A Comparator "optimized" for NullWritable.
ObjectWritable	A polymorphic Writable that writes an instance with it's class name.
SecureIOUtils	This class provides secure APIs for opening and creating files on the local disk.
SequenceFile	SequenceFiles are flat files consisting of binary key/value pairs.
SequenceFile.Metadata	The class encapsulating with the metadata of a file.
SequenceFile.Reader	Reads key/value pairs from a sequence-format file.
SequenceFile.Sorter	Sorts key/value pairs in a sequence-format file.
SequenceFile.Writer	Write key/value pairs to a sequence-format file.
SetFile	A file-based set of keys.
SetFile.Reader	Provide access to an existing set file.
SetFile.Writer	Write a new set file.
ShortWritable	A WritableComparable for shorts.
ShortWritable.Comparator	A Comparator optimized for ShortWritable.
SortedMapWritable	A Writable SortedMap.
Text	This class stores text using standard UTF8 encoding.
Text.Comparator	A WritableComparator optimized for Text keys.
TwoDArrayWritable	A Writable for 2D arrays containing a matrix of instances of a class.
UTF8.Comparator	A WritableComparator optimized for UTF8 keys.
VersionedWritable	A base class for Writables that provides version checking.
VIntWritable	A WritableComparable for integer values stored in variable-length format.
VLongWritable	A WritableComparable for longs in a variable-length format.
WritableComparator	A Comparator for WritableComparables.
WritableFactories	Factories for non-public writables.
WritableUtils

Enum Summary

Enum	Description
SequenceFile.CompressionType	The compression type used to compress key/value pairs in the SequenceFile.

Exception Summary

Exception	Description
MultipleIOException	Encapsulate a list of IOException into an IOException
SecureIOUtils.AlreadyExistsException	Signals that an attempt to create a file at a given pathname has failed because another file already existed at that path.
VersionMismatchException	Thrown by VersionedWritable.readFields(DataInput) when the version of an object being read does not match the current implementation version as returned by VersionedWritable.getVersion().

Package org.apache.hadoop.io Description

Generic i/o code for use when reading and writing data to the network, to databases, and to files.