Compression Helper Class using SharpZipLib

使用 SharpZipLib 进行压缩的辅助类，简化压缩字节数组和字符串的操作。

using System;

using System.Text;

using System.IO;

using ICSharpCode.SharpZipLib.BZip2;

using ICSharpCode.SharpZipLib.GZip;

using ICSharpCode.SharpZipLib.Zip;

namespace Compression

{

/// <summary>

/// 压缩方式。

/// </summary>

public enum CompressionType

{

GZip,

BZip2,

Zip

}

/// <summary>

/// 使用 SharpZipLib 进行压缩的辅助类，简化压缩字节数组和字符串的操作。

/// </summary>

public class CompressionHelper

{

/// <summary>

/// 压缩供应者，默认为 GZip。

/// </summary>

public static CompressionType CompressionProvider = CompressionType.GZip;

#region Public methods

/// <summary>

/// 从原始字节数组生成已压缩的字节数组。

/// </summary>

/// <param name="bytesToCompress">原始字节数组。</param>

/// <returns>返回已压缩的字节数组</returns>

public static byte[] Compress( byte[] bytesToCompress )

{

MemoryStream ms = new MemoryStream();

Stream s = OutputStream( ms );

s.Write( bytesToCompress, 0, bytesToCompress.Length );

s.Close();

return ms.ToArray();

}

/// <summary>

/// 从原始字符串生成已压缩的字符串。

/// </summary>

/// <param name="stringToCompress">原始字符串。</param>

/// <returns>返回已压缩的字符串。</returns>

public static string Compress( string stringToCompress )

{

byte[] compressedData = CompressToByte( stringToCompress );

string strOut = Convert.ToBase64String( compressedData );

return strOut;

}

/// <summary>

/// 从原始字符串生成已压缩的字节数组。

/// </summary>

/// <param name="stringToCompress">原始字符串。</param>

/// <returns>返回已压缩的字节数组。</returns>

public static byte[] CompressToByte( string stringToCompress )

{

byte[] bytData = Encoding.Unicode.GetBytes( stringToCompress );

return Compress( bytData );

}

/// <summary>

/// 从已压缩的字符串生成原始字符串。

/// </summary>

/// <param name="stringToDecompress">已压缩的字符串。</param>

/// <returns>返回原始字符串。</returns>

public string DeCompress( string stringToDecompress )

{

string outString = string.Empty;

if ( stringToDecompress == null )

{

throw new ArgumentNullException("stringToDecompress", "You tried to use an empty string");

}

try

{

byte[] inArr = Convert.FromBase64String(stringToDecompress.Trim());

outString = Encoding.Unicode.GetString(DeCompress(inArr));

}

catch (NullReferenceException nEx)

{

return nEx.Message;

}

return outString;

}

/// <summary>

/// 从已压缩的字节数组生成原始字节数组。

/// </summary>

/// <param name="bytesToDecompress">已压缩的字节数组。</param>

/// <returns>返回原始字节数组。</returns>

public static byte[] DeCompress( byte[] bytesToDecompress )

{

byte[] writeData = new byte[4096];

Stream s2 = InputStream( new MemoryStream( bytesToDecompress ) );

MemoryStream outStream = new MemoryStream();

while (true)

{

int size = s2.Read( writeData, 0, writeData.Length );

if ( size > 0 )

{

outStream.Write( writeData, 0, size );

}

else

{

break;

}

}

s2.Close();

byte[] outArr = outStream.ToArray();

outStream.Close();

return outArr;

}

#endregion

#region Private methods

/// <summary>

/// 从给定的流生成压缩输出流。

/// </summary>

/// <param name="inputStream">原始流。</param>

/// <returns>返回压缩输出流。</returns>

private static Stream OutputStream( Stream inputStream )

{

switch ( CompressionProvider )

{

case CompressionType.BZip2:

return new BZip2OutputStream( inputStream );

case CompressionType.GZip:

return new GZipOutputStream( inputStream );

case CompressionType.Zip:

return new ZipOutputStream( inputStream );

default:

return new GZipOutputStream( inputStream );

}

}

/// <summary>

/// 从给定的流生成压缩输入流。

/// </summary>

/// <param name="inputStream">原始流。</param>

/// <returns>返回压缩输入流。</returns>

private static Stream InputStream( Stream inputStream )

{

switch (CompressionProvider)

{

case CompressionType.BZip2:

return new BZip2InputStream(inputStream);

case CompressionType.GZip:

return new GZipInputStream(inputStream);

case CompressionType.Zip:

return new ZipInputStream(inputStream);

default:

return new GZipInputStream(inputStream);

}

}

#endregion

}

}

来源：http://www.mostlylucid.co.uk/archive/2004/04/06/958.aspx