Package org.apache.hadoop.io.compress

Class BZip2Codec

java.lang.Object

org.apache.hadoop.io.compress.BZip2Codec

All Implemented Interfaces:

Configurable, CompressionCodec, SplittableCompressionCodec

@Public
@Evolving
public class BZip2Codec
extends Object
implements Configurable, SplittableCompressionCodec

This class provides output and input streams for bzip2 compression and decompression. It uses the native bzip2 library on the system if possible, else it uses a pure-Java implementation of the bzip2 algorithm. The configuration parameter io.compression.codec.bzip2.library can be used to control this behavior. In the pure-Java mode, the Compressor and Decompressor interfaces are not implemented. Therefore, in that mode, those methods of CompressionCodec which have a Compressor or Decompressor type argument, throw UnsupportedOperationException. Currently, support for splittability is available only in the pure-Java mode; therefore, if a SplitCompressionInputStream is requested, the pure-Java implementation is used, regardless of the setting of the configuration parameter mentioned above.

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.hadoop.io.compress.CompressionCodec

org.apache.hadoop.io.compress.CompressionCodec.Util

Nested classes/interfaces inherited from interface org.apache.hadoop.io.compress.SplittableCompressionCodec

SplittableCompressionCodec.READ_MODE

Constructor Summary

Constructors

Constructor	Description
BZip2Codec()	Creates a new instance of BZip2Codec.

Method Summary

Modifier and Type	Method	Description
Compressor	createCompressor()	Create a new Compressor for use by this CompressionCodec.
Decompressor	createDecompressor()	Create a new Decompressor for use by this CompressionCodec.
CompressionInputStream	createInputStream(InputStream in)	Create a CompressionInputStream that will read from the given input stream and return a stream for uncompressed data.
CompressionInputStream	createInputStream(InputStream in, Decompressor decompressor)	Create a CompressionInputStream that will read from the given InputStream with the given Decompressor, and return a stream for uncompressed data.
SplitCompressionInputStream	createInputStream(InputStream seekableIn, Decompressor decompressor, long start, long end, SplittableCompressionCodec.READ_MODE readMode)	Creates CompressionInputStream to be used to read off uncompressed data in one of the two reading modes. i.e.
CompressionOutputStream	createOutputStream(OutputStream out)	Create a CompressionOutputStream that will write to the given OutputStream.
CompressionOutputStream	createOutputStream(OutputStream out, Compressor compressor)	Create a CompressionOutputStream that will write to the given OutputStream with the given Compressor.
Class<? extends Compressor>	getCompressorType()	Get the type of Compressor needed by this CompressionCodec.
Configuration	getConf()	Return the configuration used by this object.
Class<? extends Decompressor>	getDecompressorType()	Get the type of Decompressor needed by this CompressionCodec.
String	getDefaultExtension()	.bz2 is recognized as the default extension for compressed BZip2 files
void	setConf(Configuration conf)	Set the configuration to be used by this object.
static void	writeHeader(OutputStream out)

Methods inherited from class java.lang.Object

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

Constructor Details

BZip2Codec

public BZip2Codec()

Creates a new instance of BZip2Codec.

Method Details

setConf

public void setConf(Configuration conf)

Set the configuration to be used by this object.

Specified by:

setConf in interface Configurable

Parameters:

conf - the configuration object.

getConf

public Configuration getConf()

Return the configuration used by this object.

Specified by:

getConf in interface Configurable

Returns:

the configuration object used by this objec.

createOutputStream

public CompressionOutputStream createOutputStream(OutputStream out)
                                           throws IOException

Create a CompressionOutputStream that will write to the given OutputStream.

Specified by:

createOutputStream in interface CompressionCodec

Parameters:

out - the location for the final output stream

Returns:

a stream the user can write uncompressed data to, to have it compressed

Throws:

IOException - raised on errors performing I/O.

createOutputStream

public CompressionOutputStream createOutputStream(OutputStream out,
 Compressor compressor)
                                           throws IOException

Create a CompressionOutputStream that will write to the given OutputStream with the given Compressor.

Specified by:

createOutputStream in interface CompressionCodec

Parameters:

out - the location for the final output stream

compressor - compressor to use

Returns:

a stream the user can write uncompressed data to, to have it compressed

Throws:

IOException - raised on errors performing I/O.

getCompressorType

public Class<? extends Compressor> getCompressorType()

Get the type of Compressor needed by this CompressionCodec.

Specified by:

getCompressorType in interface CompressionCodec

Returns:

the type of compressor needed by this codec.

createCompressor

public Compressor createCompressor()

Create a new Compressor for use by this CompressionCodec.

Specified by:

createCompressor in interface CompressionCodec

Returns:

a new compressor for use by this codec

createInputStream

public CompressionInputStream createInputStream(InputStream in)
                                         throws IOException

Create a CompressionInputStream that will read from the given input stream and return a stream for uncompressed data.

Specified by:

createInputStream in interface CompressionCodec

Parameters:

in - the stream to read compressed bytes from

Returns:

a stream to read uncompressed bytes from

Throws:

IOException - raised on errors performing I/O.

createInputStream

public CompressionInputStream createInputStream(InputStream in,
 Decompressor decompressor)
                                         throws IOException

Create a CompressionInputStream that will read from the given InputStream with the given Decompressor, and return a stream for uncompressed data.

Specified by:

createInputStream in interface CompressionCodec

Parameters:

in - the stream to read compressed bytes from

decompressor - decompressor to use

Returns:

a stream to read uncompressed bytes from

Throws:

IOException - raised on errors performing I/O.

createInputStream

public SplitCompressionInputStream createInputStream(InputStream seekableIn,
 Decompressor decompressor,
 long start,
 long end,
 SplittableCompressionCodec.READ_MODE readMode)
                                              throws IOException

Creates CompressionInputStream to be used to read off uncompressed data in one of the two reading modes. i.e. Continuous or Blocked reading modes

Specified by:

createInputStream in interface SplittableCompressionCodec

Parameters:

seekableIn - The InputStream

start - The start offset into the compressed stream

end - The end offset into the compressed stream

readMode - Controls whether progress is reported continuously or only at block boundaries.

decompressor - decompressor.

Returns:

CompressionInputStream for BZip2 aligned at block boundaries

Throws:

IOException - raised on errors performing I/O.

getDecompressorType

public Class<? extends Decompressor> getDecompressorType()

Get the type of Decompressor needed by this CompressionCodec.

Specified by:

getDecompressorType in interface CompressionCodec

Returns:

the type of decompressor needed by this codec.

createDecompressor

public Decompressor createDecompressor()

Create a new Decompressor for use by this CompressionCodec.

Specified by:

createDecompressor in interface CompressionCodec

Returns:

a new decompressor for use by this codec

getDefaultExtension

public String getDefaultExtension()

.bz2 is recognized as the default extension for compressed BZip2 files

Specified by:

getDefaultExtension in interface CompressionCodec

Returns:

A String telling the default bzip2 file extension

writeHeader

@VisibleForTesting
public static void writeHeader(OutputStream out)
                        throws IOException

Throws:

IOException