C# 壓縮文件
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(wù)的類。
(downmoon原作)
類 說(shuō)明
DeflateStream 提供用于使用 Deflate 算法壓縮和解壓縮流的方法和屬性。
GZipStream 提供用于壓縮和解壓縮流的方法和屬性。
枚舉 說(shuō)明
CompressionMode 指定是否壓縮或解壓縮基礎(chǔ)流。
下面以 GZipStream 為例說(shuō)明
注意：此類在 .NET Framework 2.0 版中是新增的。
提供用于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(yǔ)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(shù)據(jù)格式，它使用無(wú)損壓縮和解壓縮文件的行業(yè)標(biāo)準(zhǔn)算法。這種格式包括一個(gè)檢測(cè)數(shù)據(jù)損壞的循環(huán)冗余校驗(yàn)值。GZip 數(shù)據(jù)格式使用的算法與 DeflateStream 類的算法相同，但它可以擴(kuò)展以使用其他壓縮格式。這種格式可以通過(guò)不涉及專利使用權(quán)的方式輕松實(shí)現(xiàn)。gzip 的格式可以從 RFC 1952“GZIP file format specification 4.3（GZIP 文件格式規(guī)范 4.3）GZIP file format specification 4.3（GZIP 文件格式規(guī)范 4.3）”中獲得。此類不能用于壓縮大于 4 GB 的文件。
給繼承者的說(shuō)明 當(dāng)從 GZipStream 繼承時(shí)，必須重寫(xiě)下列成員：CanSeek、CanWrite 和 CanRead。
下面提供 一個(gè)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(shí)發(fā)生錯(cuò)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 ); // 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, "解壓文件時(shí)發(fā)生錯(cuò)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 ( ); } } }
