framework 2.0 中新增的兩個壓縮類
system.io.compression 命名空間
注意：此命名空間在 .Net framework 2.0 版中是新增的。
system.io.compression 命名空間包含提供基本的流壓縮和解壓縮服務的類。
(downmoon原作)
類 說明
deflatestream 提供用於使用 deflate 算法壓縮和解壓縮流的方法和屬性。
gzipstream 提供用於壓縮和解壓縮流的方法和屬性。
枚舉 說明
compressionmode 指定是否壓縮或解壓縮基礎流。
下面以 gzipstream 為例說明
注意：此類在 .Net framework 2.0 版中是新增的。
提供用於壓縮和解壓縮流的方法和屬性。
命名空間:system.io.compression
程序集:system（在 system.dll 中）
語法
visual basic（聲明）
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
備注
此類表示 gzip 數據格式，它使用無損壓縮和解壓縮文件的行業標准算法。這種格式包括一個檢測數據損壞的循環冗余校驗值。gzip 數據格式使用的算法與 deflatestream 類的算法相同，但它可以擴展以使用其他壓縮格式。這種格式可以通過不涉及專利使用權的方式輕松實現。gzip 的格式可以從 rfc 1952“gzip file format specification 4.3（gzip 文件格式規范 4.3）gzip file format specification 4.3（gzip 文件格式規范 4.3）”中獲得。此類不能用於壓縮大於 4 gb 的文件。
給繼承者的說明 當從 gzipstream 繼承時，必須重寫下列成員：canseek、canwrite 和 canread。
下面提供 一個完整的壓縮與解壓類(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, "壓縮文件時發生錯誤：", 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 );
&nbsthe 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, "解壓文件時發生錯誤：", 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 ( );
}
}
}
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/**//// <summary>
/// FileZipLib 壓縮，解壓縮的類
/// </summary>
public class FileZipLib
...{
public FileZipLib() ...{}
/**//// <summary>
/// 創建一個壓縮文件
/// </summary>
/// <param name="zipFilename">壓縮後的文件名</param>
/// <param name="sourceDirectory">待壓縮文件的所在目錄</param>
public static voidPackFiles(string zipFilename,string sourceDirectory)
...{
FastZip fz = new FastZip() ;
fz.CreateEmptyDirectorIEs = true ;
fz.CreateZip(zipFilename,sourceDirectory,true,"") ;
fz = null ;
}
/**//// <summary>
/// 解壓縮文件
/// </summary>
/// <param name="zipFile">待解壓縮的文件</param>
/// <param name="directory">解壓縮後文件存放的目錄</param>
public static bool UnpackFiles(string zipFile,string directory)
...{
if( !Directory.Exists(directory) )
Directory.CreateDirectory(directory) ;
ZipInputStream zis = new ZipInputStream( File.OpenRead(zipFile) ) ;
ZipEntry theEntry = null ;
while( (theEntry = zis.GetNextEntry()) != null )
...{
string directoryName = Path.GetDirectoryName(theEntry.Name) ;
string fileName = Path.GetFileName(theEntry.Name) ;
if( directoryName != string.Empty )
Directory.CreateDirectory(directory + directoryName) ;
if( fileName != string.Empty )
...{
FileStream streamWriter = File.Create( Path.Combine( directory,theEntry.Name) ) ;
int size = 2048 ;
byte[] data = new byte[size] ;
while ( true )
...{
size = zis.Read(data,0,data.Length) ;
if( size > 0 )
streamWriter.Write( data,0,size ) ;
else
break ;
}
streamWriter.Close() ;
}
}
zis.Close() ;
return true ;
}
}
//最後別忘了using ICSharpCode.SharpZipLib.Zip ;
