org.apache.hadoop.io.compress

类 CompressionCodecFactory

java.lang.Object

org.apache.hadoop.io.compress.CompressionCodecFactory

public class CompressionCodecFactory
extends Object

A factory that will find the correct codec for a given filename.

字段概要

字段

限定符和类型	字段和说明
static org.apache.commons.logging.Log	LOG

构造器概要

构造器

构造器和说明
CompressionCodecFactory(Configuration conf) Find the codecs specified in the config value io.compression.codecs and register them.

方法概要

方法

限定符和类型	方法和说明
CompressionCodec	getCodec(Path file) Find the relevant compression codec for the given file based on its filename suffix.
CompressionCodec	getCodecByClassName(String classname) Find the relevant compression codec for the codec's canonical class name.
CompressionCodec	getCodecByName(String codecName) Find the relevant compression codec for the codec's canonical class name or by codec alias.
Class<? extends CompressionCodec>	getCodecClassByName(String codecName) Find the relevant compression codec for the codec's canonical class name or by codec alias and returns its implemetation class.
static List<Class<? extends CompressionCodec>>	getCodecClasses(Configuration conf) Get the list of codecs listed in the configuration
static void	main(String[] args) A little test program.
static String	removeSuffix(String filename, String suffix) Removes a suffix from a filename, if it has it.
static void	setCodecClasses(Configuration conf, List<Class> classes) Sets a list of codec classes in the configuration.
String	toString() Print the extension map out as a string.

从类继承的方法 java.lang.Object

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

字段详细资料

LOG

public static final org.apache.commons.logging.Log LOG

构造器详细资料

CompressionCodecFactory

public CompressionCodecFactory(Configuration conf)

Find the codecs specified in the config value io.compression.codecs and register them. Defaults to gzip and zip.

方法详细资料

toString

public String toString()

Print the extension map out as a string.

覆盖:

toString 在类中 Object

getCodecClasses

public static List<Class<? extends CompressionCodec>> getCodecClasses(Configuration conf)

Get the list of codecs listed in the configuration

参数:

conf - the configuration to look in

返回:

a list of the Configuration classes or null if the attribute was not set

setCodecClasses

public static void setCodecClasses(Configuration conf,
                   List<Class> classes)

Sets a list of codec classes in the configuration.

参数:

conf - the configuration to modify

classes - the list of classes to set

getCodec

public CompressionCodec getCodec(Path file)

Find the relevant compression codec for the given file based on its filename suffix.

参数:

file - the filename to check

返回:

the codec object

getCodecByClassName

public CompressionCodec getCodecByClassName(String classname)

Find the relevant compression codec for the codec's canonical class name.

参数:

classname - the canonical class name of the codec

返回:

the codec object

getCodecByName

public CompressionCodec getCodecByName(String codecName)

Find the relevant compression codec for the codec's canonical class name or by codec alias.

Codec aliases are case insensitive.

The code alias is the short class name (without the package name). If the short class name ends with 'Codec', then there are two aliases for the codec, the complete short class name and the short class name without the 'Codec' ending. For example for the 'GzipCodec' codec class name the alias are 'gzip' and 'gzipcodec'.

参数:

codecName - the canonical class name of the codec

返回:

the codec object

getCodecClassByName

public Class<? extends CompressionCodec> getCodecClassByName(String codecName)

Find the relevant compression codec for the codec's canonical class name or by codec alias and returns its implemetation class.

Codec aliases are case insensitive.

The code alias is the short class name (without the package name). If the short class name ends with 'Codec', then there are two aliases for the codec, the complete short class name and the short class name without the 'Codec' ending. For example for the 'GzipCodec' codec class name the alias are 'gzip' and 'gzipcodec'.

参数:

codecName - the canonical class name of the codec

返回:

the codec class

removeSuffix

public static String removeSuffix(String filename,
                  String suffix)

Removes a suffix from a filename, if it has it.

参数:

filename - the filename to strip

suffix - the suffix to remove

返回:

the shortened filename

main

public static void main(String[] args)
                 throws Exception

A little test program.

参数:

args -

抛出:

Exception