.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 )：
class clsZip
{
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 ( );
}
}
}
