我在做项目的时候需要将文件进行压缩和解压缩，于是就从http://www.icsharpcode.net下载了关于压缩和解压缩的源码，但是下载下来后，面对这么多的代码，一时不知如何下手。只好耐下心来，慢慢的研究，总算找到了门路。针对自己的需要改写了文件压缩和解压缩的两个类，分别为ZipClass和UnZipClass。其中碰到了不少困难，就决定写出来压缩和解压的程序后，一定把源码贴出来共享，让首次接触压缩和解压缩的朋友可以少走些弯路。下面就来解释如何在C#里用http://www.icsharpcode.net下载的SharpZipLib进行文件的压缩和解压缩。

首先需要在项目里引用SharpZipLib.dll。然后修改其中的关于压缩和解压缩的类。实现源码如下：

/// <summary>
/// 压缩文件
/// </summary>

using System;
using System.IO;

using ICSharpCode.SharpZipLib.Checksums;
using ICSharpCode.SharpZipLib.Zip;
using ICSharpCode.SharpZipLib.GZip;

namespace Compression
{
public class ZipClass
{

public void ZipFile(string FileToZip, string ZipedFile ,int CompressionLevel, int BlockSize)
{
//如果文件没有找到，则报错
if (! System.IO.File.Exists(FileToZip))
{
throw new System.IO.FileNotFoundException("The specified file " + FileToZip + " could not be found. Zipping aborderd");
}

System.IO.FileStream StreamToZip = new System.IO.FileStream(FileToZip,System.IO.FileMode.Open , System.IO.FileAccess.Read);
System.IO.FileStream ZipFile = System.IO.File.Create(ZipedFile);
ZipOutputStream ZipStream = new ZipOutputStream(ZipFile);
ZipEntry ZipEntry = new ZipEntry("ZippedFile");
ZipStream.PutNextEntry(ZipEntry);
ZipStream.SetLevel(CompressionLevel);
byte[] buffer = new byte[BlockSize];
System.Int32 size =StreamToZip.Read(buffer,0,buffer.Length);
ZipStream.Write(buffer,0,size);
try
{
while (size < StreamToZip.Length)
{
int sizeRead =StreamToZip.Read(buffer,0,buffer.Length);
ZipStream.Write(buffer,0,sizeRead);
size += sizeRead;
}
}
catch(System.Exception ex)
{
throw ex;
}
ZipStream.Finish();
ZipStream.Close();
StreamToZip.Close();
}

public void ZipFileMain(string[] args)
{
string[] filenames = Directory.GetFiles(args[0]);

Crc32 crc = new Crc32();
ZipOutputStream s = new ZipOutputStream(File.Create(args[1]));

s.SetLevel(6); // 0 - store only to 9 - means best compression

foreach (string file in filenames)
{
//打开压缩文件
FileStream fs = File.OpenRead(file);

byte[] buffer = new byte[fs.Length];
fs.Read(buffer, 0, buffer.Length);
ZipEntry entry = new ZipEntry(file);

entry.DateTime = DateTime.Now;

// set Size and the crc, because the information
// about the size and crc should be stored in the header
// if it is not set it is automatically written in the footer.
// (in this case size == crc == -1 in the header)
// Some ZIP programs have problems with zip files that don't store
// the size and crc in the header.
entry.Size = fs.Length;
fs.Close();

crc.Reset();
crc.Update(buffer);

entry.Crc = crc.Value;

s.PutNextEntry(entry);

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

}

s.Finish();
s.Close();
}
}
}

现在再来看看解压文件类的源码

/// <summary>
/// 解压文件
/// </summary>

using System;
using System.Text;
using System.Collections;
using System.IO;
using System.Diagnostics;
using System.Runtime.Serialization.Formatters.Binary;
using System.Data;

using ICSharpCode.SharpZipLib.BZip2;
using ICSharpCode.SharpZipLib.Zip;
using ICSharpCode.SharpZipLib.Zip.Compression;
using ICSharpCode.SharpZipLib.Zip.Compression.Streams;
using ICSharpCode.SharpZipLib.GZip;

namespace DeCompression
{
public class UnZipClass
{
public void UnZip(string[] args)
{
ZipInputStream s = new