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

Closeable	Deprecated. use java.io.Closeable
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.Sorter.RawKeyValueIterator	The interface to iterate over raw keys/values of SequenceFiles.
SequenceFile.ValueBytes	The interface to 'raw' values of SequenceFiles.
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

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.
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.
DataInputBuffer	A reusable DataInput implementation that reads from an in-memory buffer.
DataOutputBuffer	A reusable DataOutput implementation that writes to an in-memory buffer.
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.
FloatWritable	A WritableComparable for floats.
FloatWritable.Comparator	A Comparator optimized for FloatWritable.
GenericWritable	A wrapper for Writable instances.
InputBuffer	A reusable InputStream implementation that reads from an in-memory buffer.
IntWritable	A WritableComparable for ints.
IntWritable.Comparator	A Comparator optimized for IntWritable.
IOUtils	An utility class for I/O related functionality.
IOUtils.NullOutputStream	/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.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.
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.
OutputBuffer	A reusable OutputStream implementation that writes to an in-memory buffer.
ReadaheadPool	Manages a pool of threads which can issue readahead requests on file descriptors.
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.
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	Deprecated. replaced by Text
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.
WritableName	Utility to permit renaming of Writable implementation classes without invalidiating files that contain their class name.
WritableUtils

Enum Summary

SequenceFile.CompressionType

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

Exception Summary

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.