.NET Framework 2.0 中新增的两个压缩类
System.IO.Compression 命名空间
注意：此命名空间在 .NET Framework 2.0 版中是新增的。
System.IO.Compression 命名空间包含提供基本的流压缩和解压缩服务的类。
(downmoon原作)
类 说明
DeflateStream 提供用于使用 Deflate 算法压缩和解压缩流的方法和属性。
GZipStream 提供用于压缩和解压缩流的方法和属性。
枚举 说明
CompressionMode 指定是否压缩或解压缩基础流。
下面以 GZipStream 为例说明
注意：此类在 .NET Framework 2.0 版中是新增的。
提供用于压缩和解压缩流的方法和属性。
命名空间:System.IO.Compression
程序集:System（在 system.dll 中）
语法
Visual Basic（声明）
Public Class GZipStream
Inherits Stream
Visual Basic（用法）
Dim instance As GZipStream
C#
public class GZipStream : Stream
C++
public ref class GZipStream : public Stream
J#
public class GZipStream extends Stream
JScript
public class GZipStream extends Stream
备注
此类表示 GZip 数据格式，它使用无损压缩和解压缩文件的行业标准算法。这种格式包括一个检测数据损坏的循环冗余校验值。GZip 数据格式使用的算法与 DeflateStream 类的算法相同，但它可以扩展以使用其他压缩格式。这种格式可以通过不涉及专利使用权的方式轻松实现。gzip 的格式可以从 RFC 1952“GZIP file format specification 4.3（GZIP 文件格式规范 4.3）GZIP file format specification 4.3（GZIP 文件格式规范 4.3）”中获得。此类不能用于压缩大于 4 GB 的文件。
给继承者的说明 当从 GZipStream 继承时，必须重写下列成员：CanSeek、CanWrite 和 CanRead。
下面提供 一个完整的压缩与解压类(downmoon原作 )：
classclsZip
{
public
void
CompressFile (
string
sourceFile,
string
destinationFile )
{
//
make sure the source file is there
if
( File.Exists ( sourceFile )
==
false
)
throw
new
FileNotFoundException ( );
//
Create the streams and byte arrays needed
byte
[] buffer
=
null
;
FileStream sourceStream
=
null
;
FileStream destinationStream
=
null
;
GZipStream compressedStream
=
null
;
try
{
//
Read the bytes from the source file into a byte array
sourceStream
=
new
FileStream ( sourceFile, FileMode.Open, FileAccess.Read, FileShare.Read );
//
Read the source stream values into the buffer
buffer
=
new
byte
[sourceStream.Length];
int
checkCounter
=
sourceStream.Read ( buffer,
0
, buffer.Length );
if
( checkCounter
!=
buffer.Length )
{
throw
new
ApplicationException ( );
}
//
Open the FileStream to write to
destinationStream
=
new
FileStream ( destinationFile, FileMode.OpenOrCreate, FileAccess.Write );
//
Create a compression stream pointing to the destiantion stream
compressedStream
=
new
GZipStream ( destinationStream, CompressionMode.Compress,
true
);
//
Now write the compressed data to the destination file
compressedStream.Write ( buffer,
0
, buffer.Length );
}
catch
( ApplicationException ex )
{
MessageBox.Show ( ex.Message,
"
压缩文件时发生错误：
"
, MessageBoxButtons.OK, MessageBoxIcon.Error );
}
finally
{
//
Make sure we allways close all streams
if
( sourceStream
!=
null
)
sourceStream.Close ( );
if
( compressedStream
!=
null
)
compressedStream.Close ( );
if
( destinationStream
!=
null
)
destinationStream.Close ( );
}
}
public
void
DecompressFile (
string
sourceFile,
string
destinationFile )
{
//
make sure the source file is there
if
( File.Exists ( sourceFile )
==
false
)
throw
new
FileNotFoundException ( );
//
Create the streams and byte arrays needed
FileStream sourceStream
=
null
;
FileStream destinationStream
=
null
;
GZipStream decompressedStream
=
null
;
byte
[] quartetBuffer
=
null
;
try
{
//
Read in the compressed source stream
sourceStream
=
new
FileStream ( sourceFile, FileMode.Open );
//
Create a compression stream pointing to the destiantion stream
decompressedStream
=
new
GZipStream ( sourceStream, CompressionMode.Decompress,
true
);
//
Read the footer to determine the length of the destiantion file
quartetBuffer
=
new
byte
[
4
];
int
position
=
(
int
)sourceStream.Length
-
4
;
sourceStream.Position
=
position;
sourceStream.Read ( quartetBuffer,
0
,
4
);
sourceStream.Position
=
0
;
int
checkLength
=
BitConverter.ToInt32 ( quartetBuffer,
0
);
byte
[] buffer
=
new
byte
[checkLength
+
100
];
int
offset
=
0
;
int
total
=
0
;
//
Read the compressed data into the buffer
while
(
true
)
{
int
bytesRead
=
decompressedStream.Read ( buffer, offset,
100
);
if
( bytesRead
==
0
)
break
;
offset
+=
bytesRead;
total
+=
bytesRead;
}
//
Now write everything to the destination file
destinationStream
=
new
FileStream ( destinationFile, FileMode.Create );
destinationStream.Write ( buffer,
0
, total );
//
and flush everyhting to clean out the buffer
destinationStream.Flush ( );
}
catch
( ApplicationException ex )
{
MessageBox.Show(ex.Message,
"
解压文件时发生错误：
"
, MessageBoxButtons.OK, MessageBoxIcon.Error);
}
finally
{
//
Make sure we allways close all streams
if
( sourceStream
!=
null
)
sourceStream.Close ( );
if
( decompressedStream
!=
null
)
decompressedStream.Close ( );
if
( destinationStream
!=
null
)
destinationStream.Close ( );
}
}
}