org.apache.hadoop.io.compress.zlib

类 ZlibCompressor

java.lang.Object

org.apache.hadoop.io.compress.zlib.ZlibCompressor

所有已实现的接口:

Compressor

public class ZlibCompressor
extends Object
implements Compressor

A Compressor based on the popular zlib compression algorithm. http://www.zlib.net/

嵌套类概要

嵌套类

限定符和类型	类和说明
static class	ZlibCompressor.CompressionHeader The type of header for compressed data.
static class	ZlibCompressor.CompressionLevel The compression level for zlib library.
static class	ZlibCompressor.CompressionStrategy The compression level for zlib library.

构造器概要

构造器

构造器和说明
ZlibCompressor() Creates a new compressor with the default compression level.
ZlibCompressor(Configuration conf) Creates a new compressor, taking settings from the configuration.
ZlibCompressor(ZlibCompressor.CompressionLevel level, ZlibCompressor.CompressionStrategy strategy, ZlibCompressor.CompressionHeader header, int directBufferSize) Creates a new compressor using the specified compression level.

方法概要

方法

限定符和类型	方法和说明
int	compress(byte[] b, int off, int len) Fills specified buffer with compressed data.
protected void	construct(ZlibCompressor.CompressionLevel level, ZlibCompressor.CompressionStrategy strategy, ZlibCompressor.CompressionHeader header, int directBufferSize)
void	end() Closes the compressor and discards any unprocessed input.
void	finish() When called, indicates that compression should end with the current contents of the input buffer.
boolean	finished() Returns true if the end of the compressed data output stream has been reached.
long	getBytesRead() Returns the total number of uncompressed bytes input so far.
long	getBytesWritten() Returns the total number of compressed bytes output so far.
boolean	needsInput() Returns true if the input data buffer is empty and #setInput() should be called to provide more input.
void	reinit(Configuration conf) Prepare the compressor to be used in a new stream with settings defined in the given Configuration.
void	reset() Resets compressor so that a new set of input data can be processed.
void	setDictionary(byte[] b, int off, int len) Sets preset dictionary for compression.
void	setInput(byte[] b, int off, int len) Sets input data for compression.

从类继承的方法 java.lang.Object

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

构造器详细资料

ZlibCompressor

public ZlibCompressor()

Creates a new compressor with the default compression level. Compressed data will be generated in ZLIB format.

ZlibCompressor

public ZlibCompressor(Configuration conf)

Creates a new compressor, taking settings from the configuration.

ZlibCompressor

public ZlibCompressor(ZlibCompressor.CompressionLevel level,
              ZlibCompressor.CompressionStrategy strategy,
              ZlibCompressor.CompressionHeader header,
              int directBufferSize)

Creates a new compressor using the specified compression level. Compressed data will be generated in ZLIB format.

参数:

level - Compression level #CompressionLevel

strategy - Compression strategy #CompressionStrategy

header - Compression header #CompressionHeader

directBufferSize - Size of the direct buffer to be used.

方法详细资料

construct

protected final void construct(ZlibCompressor.CompressionLevel level,
             ZlibCompressor.CompressionStrategy strategy,
             ZlibCompressor.CompressionHeader header,
             int directBufferSize)

reinit

public void reinit(Configuration conf)

Prepare the compressor to be used in a new stream with settings defined in the given Configuration. It will reset the compressor's compression level and compression strategy.

指定者:

reinit 在接口中 Compressor

参数:

conf - Configuration storing new settings

setInput

public void setInput(byte[] b,
            int off,
            int len)

从接口复制的说明: Compressor

Sets input data for compression. This should be called whenever #needsInput() returns true indicating that more input data is required.

指定者:

setInput 在接口中 Compressor

参数:

b - Input data

off - Start offset

len - Length

setDictionary

public void setDictionary(byte[] b,
                 int off,
                 int len)

从接口复制的说明: Compressor

Sets preset dictionary for compression. A preset dictionary is used when the history buffer can be predetermined.

指定者:

setDictionary 在接口中 Compressor

参数:

b - Dictionary data bytes

off - Start offset

len - Length

needsInput

public boolean needsInput()

从接口复制的说明: Compressor

Returns true if the input data buffer is empty and #setInput() should be called to provide more input.

指定者:

needsInput 在接口中 Compressor

返回:

true if the input data buffer is empty and #setInput() should be called in order to provide more input.

finish

public void finish()

从接口复制的说明: Compressor

When called, indicates that compression should end with the current contents of the input buffer.

指定者:

finish 在接口中 Compressor

finished

public boolean finished()

从接口复制的说明: Compressor

Returns true if the end of the compressed data output stream has been reached.

指定者:

finished 在接口中 Compressor

返回:

true if the end of the compressed data output stream has been reached.

compress

public int compress(byte[] b,
           int off,
           int len)
             throws IOException

从接口复制的说明: Compressor

Fills specified buffer with compressed data. Returns actual number of bytes of compressed data. A return value of 0 indicates that needsInput() should be called in order to determine if more input data is required.

指定者:

compress 在接口中 Compressor

参数:

b - Buffer for the compressed data

off - Start offset of the data

len - Size of the buffer

返回:

The actual number of bytes of compressed data.

抛出:

IOException

getBytesWritten

public long getBytesWritten()

Returns the total number of compressed bytes output so far.

指定者:

getBytesWritten 在接口中 Compressor

返回:

the total (non-negative) number of compressed bytes output so far

getBytesRead

public long getBytesRead()

Returns the total number of uncompressed bytes input so far.

指定者:

getBytesRead 在接口中 Compressor

返回:

the total (non-negative) number of uncompressed bytes input so far

reset

public void reset()

从接口复制的说明: Compressor

Resets compressor so that a new set of input data can be processed.

指定者:

reset 在接口中 Compressor

end

public void end()

从接口复制的说明: Compressor

Closes the compressor and discards any unprocessed input.

指定者:

end 在接口中 Compressor