利用SharpZipLib进行字符串的压缩和解压缩

http://www.izhangheng.com/sharpziplib-string-compression-decompression/

今天搞了一晚上压缩和解压缩问题，java压缩的字符串，用C#始终没解开，后来考虑到实际的应用，还是数据库存储压力，不适合存储压缩后的长字符串，决定去掉压缩，用明文，在其他地方处理保密问题。

不过，今天找了一个很好用的压缩/解压缩方法，首先需要去http://www.icsharpcode.net/下载SharpZipLib，然后引用ICSharpCode.SharpZipLib.dll

类如下，可以直接使用。

[csharp]
using System;
using System.Text;
using System.IO;
using ICSharpCode.SharpZipLib.BZip2;
using ICSharpCode.SharpZipLib.GZip;
using ICSharpCode.SharpZipLib.Zip;

namespace henry24264.com.Common
{
/// <summary>
/// 压缩方式。
/// </summary>
public enum CompressionType
{
/// <summary>
/// GZip 压缩格式
/// </summary>
GZip,
/// <summary>
/// BZip2 压缩格式
/// </summary>
BZip2,
/// <summary>
/// Zip 压缩格式
/// </summary>
Zip
}
/// <summary>
/// 使用 SharpZipLib 进行压缩的辅助类，简化对字节数组和字符串进行压缩的操作。
/// </summary>
public class CompressionHelper
{
/// <summary>
/// 压缩供应者，默认为 GZip。
/// </summary>
public static CompressionType CompressionProvider = CompressionType.GZip;

/// <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;
}

/// <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);
}
}
}
}
[/csharp]