C# Class NetWrok.HTTP.Zlib.GZipStream

A class for compressing and decompressing GZIP streams.

Like the GZipStream in the .NET Base Class Library, the Ionic.Zlib.GZipStream can compress while writing, or decompress while reading, but not vice versa.

A GZipStream can be used for Read() or Write(), and thus decompression or compression, but not both.

If you wish to use the GZipStream to compress (deflate) data, you must wrap it around a write-able stream. As you call Write() on the GZipStream, the data will be compressed into the GZIP (IETF RFC 1952) format.

If you want to decompress (inflate) data, you must wrap the GZipStream around a readable stream that contains an IETF RFC 1952-compliant stream. The data will be decompressed as you call Read() on the GZipStream.

Though the GZIP format allows data from multiple files to be concatenated together, this stream handles only a single segment of GZIP format, typically representing a single file.

For more information on GZIP, see IETF RFC 1952, "GZIP file format specification version 4.3".

This class is similar to ZlibStream and DeflateStream. ZlibStream handles RFC1950-compliant streams. DeflateStream handles RFC1951-compliant streams. And this class handles RFC1952-compliant streams.

Inheritance: System.IO.Stream

Show file Open project: simonwittber/netwrok-client Class Usage Examples

Public Properties

Property	Type	Description
Comment	String
LastModified	DateTime?

Public Methods

Method	Description
Close ( ) : void	Close the stream. This may or may not close the captive stream. See the ctor's with leaveOpen parameters for more information.
Flush ( ) : void	Flush the stream.
GZipStream ( System stream, CompressionMode mode ) : System	Create a GZipStream using the specified CompressionMode. The GZipStream will use the default compression level. As noted in the class documentation, the CompressionMode (Compress or Decompress) also establishes the "direction" of the stream. A GZipStream with CompressionMode.Compress works only through Write(). A GZipStream with CompressionMode.Decompress works only through Read().
GZipStream ( System stream, CompressionMode mode, CompressionLevel level ) : System	Create a GZipStream using the specified CompressionMode and the specified CompressionLevel. As noted in the class documentation, the CompressionMode (Compress or Decompress) also establishes the "direction" of the stream. A GZipStream with CompressionMode.Compress works only through Write(). A GZipStream with CompressionMode.Decompress works only through Read().
GZipStream ( System stream, CompressionMode mode, CompressionLevel level, bool leaveOpen ) : System	Create a GZipStream using the specified CompressionMode and the specified CompressionLevel, and explicitly specify whether the stream should be left open after Deflation or Inflation. This constructor allows the application to request that the captive stream remain open after the deflation or inflation occurs. By default, after Close() is called on the stream, the captive stream is also closed. In some cases this is not desired, for example if the stream is a memory stream that will be re-read after compressed data has been written to it. Specify true for the leaveOpen parameter to leave the stream open. As noted in the class documentation, the CompressionMode (Compress or Decompress) also establishes the "direction" of the stream. A GZipStream with CompressionMode.Compress works only through Write(). A GZipStream with CompressionMode.Decompress works only through Read().
GZipStream ( System stream, CompressionMode mode, bool leaveOpen ) : System	Create a GZipStream using the specified CompressionMode, and explicitly specify whether the stream should be left open after Deflation or Inflation. This constructor allows the application to request that the captive stream remain open after the deflation or inflation occurs. By default, after Close() is called on the stream, the captive stream is also closed. In some cases this is not desired, for example if the stream is a memory stream that will be re-read after compressed data has been written to it. Specify true for the leaveOpen parameter to leave the stream open. As noted in the class documentation, the CompressionMode (Compress or Decompress) also establishes the "direction" of the stream. A GZipStream with CompressionMode.Compress works only through Write(). A GZipStream with CompressionMode.Decompress works only through Read(). The DeflateStream will use the default compression level. See the other overloads of this constructor for example code.
Read ( byte buffer, int offset, int count ) : int	Read and decompress data from the source stream. With a GZipStream, decompression is done through reading.
Seek ( long offset, System origin ) : long	Calling this method always throws a NotImplementedException.
SetLength ( long value ) : void	Calling this method always throws a NotImplementedException.
Write ( byte buffer, int offset, int count ) : void	Write data to the stream. If you wish to use the GZipStream to compress data while writing, you can create a GZipStream with CompressionMode.Compress, and a writable output stream. Then call Write() on that GZipStream, providing uncompressed data as input. The data sent to the output stream will be the compressed form of the data written. If you wish to use the DeflateStream to decompress data while writing, you can create a GZipStream with CompressionMode.Decompress, and a writable output stream. Then call Write() on that stream, providing previously compressed data. The data sent to the output stream will be the decompressed form of the data written. A GZipStream can be used for Read() or Write(), but not both.

Private Methods

Method	Description
EmitHeader ( ) : void
SlurpHeader ( byte buffer, int offset ) : int
SlurpZeroTerminatedString ( byte buffer, int offset, int &count ) : string

Method Details

Close() public method

Close the stream.

This may or may not close the captive stream. See the ctor's with leaveOpen parameters for more information.

public Close ( ) : void
return	void

Flush() public method

Flush the stream.

public Flush ( ) : void
return	void

GZipStream() public method

Create a GZipStream using the specified CompressionMode.

The GZipStream will use the default compression level.

As noted in the class documentation, the CompressionMode (Compress or Decompress) also establishes the "direction" of the stream. A GZipStream with CompressionMode.Compress works only through Write(). A GZipStream with CompressionMode.Decompress works only through Read().

public GZipStream ( System stream, CompressionMode mode ) : System
stream	System	The stream which will be read or written.
mode	CompressionMode	Indicates whether the GZipStream will compress or decompress.
return	System

GZipStream() public method

Create a GZipStream using the specified CompressionMode and the specified CompressionLevel.

public GZipStream ( System stream, CompressionMode mode, CompressionLevel level ) : System
stream	System	The stream to be read or written while deflating or inflating.
mode	CompressionMode	Indicates whether the GZipStream will compress or decompress.
level	CompressionLevel	A tuning knob to trade speed for effectiveness.
return	System

GZipStream() public method

Create a GZipStream using the specified CompressionMode and the specified CompressionLevel, and explicitly specify whether the stream should be left open after Deflation or Inflation.

This constructor allows the application to request that the captive stream remain open after the deflation or inflation occurs. By default, after Close() is called on the stream, the captive stream is also closed. In some cases this is not desired, for example if the stream is a memory stream that will be re-read after compressed data has been written to it. Specify true for the leaveOpen parameter to leave the stream open.

public GZipStream ( System stream, CompressionMode mode, CompressionLevel level, bool leaveOpen ) : System
stream	System	The stream which will be read or written.
mode	CompressionMode	Indicates whether the GZipStream will compress or decompress.
level	CompressionLevel	A tuning knob to trade speed for effectiveness.
leaveOpen	bool	true if the application would like the stream to remain open after inflation/deflation.
return	System

GZipStream() public method

Create a GZipStream using the specified CompressionMode, and explicitly specify whether the stream should be left open after Deflation or Inflation.

The DeflateStream will use the default compression level.

See the other overloads of this constructor for example code.

public GZipStream ( System stream, CompressionMode mode, bool leaveOpen ) : System
stream	System	The stream which will be read or written. This is called the /// "captive" stream in other places in this documentation.
mode	CompressionMode	Indicates whether the GZipStream will compress or decompress.
leaveOpen	bool	true if the application would like the base stream to remain open after inflation/deflation.
return	System

Read() public method

Read and decompress data from the source stream.

With a GZipStream, decompression is done through reading.

public Read ( byte buffer, int offset, int count ) : int
buffer	byte	The buffer into which the decompressed data should be placed.
offset	int	the offset within that data array to put the first byte read.
count	int	the number of bytes to read.
return	int

Seek() public method

Calling this method always throws a NotImplementedException.

public Seek ( long offset, System origin ) : long
offset	long	this is irrelevant, since it will always throw!
origin	System	this is irrelevant, since it will always throw!
return	long

SetLength() public method

Calling this method always throws a NotImplementedException.

public SetLength ( long value ) : void
value	long	this is irrelevant, since it will always throw!
return	void

Write() public method

Write data to the stream.

If you wish to use the GZipStream to compress data while writing, you can create a GZipStream with CompressionMode.Compress, and a writable output stream. Then call Write() on that GZipStream, providing uncompressed data as input. The data sent to the output stream will be the compressed form of the data written. If you wish to use the DeflateStream to decompress data while writing, you can create a GZipStream with CompressionMode.Decompress, and a writable output stream. Then call Write() on that stream, providing previously compressed data. The data sent to the output stream will be the decompressed form of the data written.

A GZipStream can be used for Read() or Write(), but not both.

public Write ( byte buffer, int offset, int count ) : void
buffer	byte	The buffer holding data to write to the stream.
offset	int	the offset within that data array to find the first byte to write.
count	int	the number of bytes to write.
return	void

Property Details

Comment public property

The Comment on the GZIP stream.

The GZIP format allows for each file to have an associated comment stored with the file. The comment is encoded with the ISO-8859-1 code page. To include a comment in a GZIP stream you create, set this Comment before calling Write() for the first time on the GZipStream. When using GZipStream to decompress, you can retrieve this comment after the first call to Read().

public String Comment
return	String

LastModified public property

The last modified time for the GZIP stream.

GZIP allows the storage of a last modified time with each GZIP entry. When compressing data, you can set this before the first call to Write(). When decompressing, you can retrieve this value any time after the first call to Read().

public DateTime? LastModified
return	DateTime?