org.apache.hadoop.io.compress.zlib

类 BuiltInGzipDecompressor

java.lang.Object

org.apache.hadoop.io.compress.zlib.BuiltInGzipDecompressor

所有已实现的接口:

Decompressor

@DoNotPool
public class BuiltInGzipDecompressor
extends Object
implements Decompressor

A Decompressor based on the popular gzip compressed file format. http://www.gzip.org/

构造器概要

构造器

构造器和说明
BuiltInGzipDecompressor() Creates a new (pure Java) gzip decompressor.

方法概要

方法

限定符和类型	方法和说明
int	decompress(byte[] b, int off, int len) Decompress the data (gzip header, deflate stream, gzip trailer) in the provided buffer.
void	end() Closes the decompressor and discards any unprocessed input.
boolean	finished() Returns true if the end of the gzip substream (single "member") has been reached.
long	getBytesRead() Returns the total number of compressed bytes input so far, including gzip header/trailer bytes.
int	getRemaining() Returns the number of bytes remaining in the input buffer; normally called when finished() is true to determine amount of post-gzip-stream data.
boolean	needsDictionary() Returns true if a preset dictionary is needed for decompression.
boolean	needsInput() Returns true if the input data buffer is empty and Decompressor.setInput(byte[], int, int) should be called to provide more input.
void	reset() Resets everything, including the input buffer, regardless of whether the current gzip substream is finished.
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 decompression.

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

BuiltInGzipDecompressor

public BuiltInGzipDecompressor()

Creates a new (pure Java) gzip decompressor.

方法详细资料

needsInput

public boolean needsInput()

Returns true if the input data buffer is empty and Decompressor.setInput(byte[], int, int) should be called to provide more input.

指定者:

needsInput 在接口中 Decompressor

返回:

true if the input data buffer is empty and Decompressor.setInput(byte[], int, int) should be called in order to provide more input.

setInput

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

Sets input data for decompression. This should be called if and only if Decompressor.needsInput() returns true indicating that more input data is required. (Both native and non-native versions of various Decompressors require that the data passed in via b[] remain unmodified until the caller is explicitly notified--via Decompressor.needsInput()--that the buffer may be safely modified. With this requirement, an extra buffer-copy can be avoided.)

指定者:

setInput 在接口中 Decompressor

参数:

b - Input data

off - Start offset

len - Length

decompress

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

Decompress the data (gzip header, deflate stream, gzip trailer) in the provided buffer.

指定者:

decompress 在接口中 Decompressor

参数:

b - Buffer for the compressed data

off - Start offset of the data

len - Size of the buffer

返回:

the number of decompressed bytes placed into b

抛出:

IOException

getBytesRead

public long getBytesRead()

Returns the total number of compressed bytes input so far, including gzip header/trailer bytes.

返回:

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

getRemaining

public int getRemaining()

Returns the number of bytes remaining in the input buffer; normally called when finished() is true to determine amount of post-gzip-stream data. Note that, other than the finished state with concatenated data after the end of the current gzip stream, this will never return a non-zero value unless called after setInput(byte[] b, int off, int len) and before decompress(byte[] b, int off, int len). (That is, after decompress(byte[] b, int off, int len) it always returns zero, except in finished state with concatenated data.)

指定者:

getRemaining 在接口中 Decompressor

返回:

the total (non-negative) number of unprocessed bytes in input

needsDictionary

public boolean needsDictionary()

Returns true if a preset dictionary is needed for decompression.

指定者:

needsDictionary 在接口中 Decompressor

返回:

true if a preset dictionary is needed for decompression

setDictionary

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

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 Decompressor

参数:

b - Dictionary data bytes

off - Start offset

len - Length

finished

public boolean finished()

Returns true if the end of the gzip substream (single "member") has been reached.

指定者:

finished 在接口中 Decompressor

返回:

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

reset

public void reset()

Resets everything, including the input buffer, regardless of whether the current gzip substream is finished.

指定者:

reset 在接口中 Decompressor

end

public void end()

Closes the decompressor and discards any unprocessed input.

指定者:

end 在接口中 Decompressor