using System;
using System.IO;
using ICSharpCode.SharpZipLib.Zip;
using ICSharpCode.SharpZipLib.GZip;
using ICSharpCode.SharpZipLib.BZip2;
using ICSharpCode.SharpZipLib.Checksums;
using ICSharpCode.SharpZipLib.Zip.Compression;
using ICSharpCode.SharpZipLib.Zip.Compression.Streams;

namespace WebApplication3
{
    ZipClass 压缩文件#region ZipClass 压缩文件
    public class ZipClass
    {
        public void ZipFile(string FileToZip, string ZipedFile ,int CompressionLevel, int BlockSize,string password)
        {
            //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]);
            string[] filenames = new string[]{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();
        }
    }
    #endregion

    UnZipClass 解压文件#region UnZipClass 解压文件
    public class UnZipClass
    {   
        /**//// <summary>
        /// 解压文件
        /// </summary>
        /// <param name="args">包含要解压的文件名和要解压到的目录名数组</param>
        public void UnZip(string[] args)
        {
            ZipInputStream s = new ZipInputStream(File.OpenRead(args[0]));
            try
            {                
                ZipEntry theEntry;
                while ((theEntry = s.GetNextEntry()) != null) 
                {   
                    string directoryName = Path.GetDirectoryName(args[1]);
                    string fileName      = Path.GetFileName(theEntry.Name);
   
                    //生成解压目录
                    Directory.CreateDirectory(directoryName);
   
                    if (fileName != String.Empty) 
                    {   
                        //解压文件到指定的目录
                        FileStream streamWriter = File.Create(args[1]+fileName);
    
                        int size = 2048;
                        byte[] data = new byte[2048];
                        while (true) 
                        {
                            size = s.Read(data, 0, data.Length);
                            if (size > 0) 
                            {
                                streamWriter.Write(data, 0, size);
                            } 
                            else 
                            {
                                break;
                            }
                        }
    
                        streamWriter.Close();
                    }
                }
                s.Close();
            }
            catch(Exception eu)
            {
                throw eu;
            }
            finally
            {
                s.Close();
            }

        }//end UnZip


    }//end UnZipClass
    #endregion

    AttachmentUnZip#region AttachmentUnZip
    public class AttachmentUnZip
    {
        public AttachmentUnZip()
        {            
        }
        public static void UpZip(string zipFile)
        {
            string []FileProperties=new string[2];

            FileProperties[0]=zipFile;//待解压的文件

            FileProperties[1]=zipFile.Substring(0,zipFile.LastIndexOf("\\")+1);//解压后放置的目标目录

            UnZipClass UnZc=new UnZipClass();

            UnZc.UnZip(FileProperties);
        }

    }
    #endregion
}

<HTML>
    <HEAD>
        <title>WebForm1</title>
        <meta name="GENERATOR" Content="Microsoft Visual Studio .NET 7.1">
        <meta name="CODE_LANGUAGE" Content="C#">
        <meta name="vs_defaultClientScript" content="JavaScript">
        <meta name="vs_targetSchema" content="http://schemas.microsoft.com/intellisense/ie5">
    </HEAD>
    <body MS_POSITIONING="GridLayout">
        <form id="Form1" method="post" runat="server">
            <asp:Button id="Button1" style="Z-INDEX: 101; LEFT: 56px; POSITION: absolute; TOP: 64px" runat="server"
                Text="压缩"></asp:Button>
            <asp:Button id="Button2" style="Z-INDEX: 102; LEFT: 112px; POSITION: absolute; TOP: 64px" runat="server"
                Text="解压"></asp:Button><INPUT id="File1" style="Z-INDEX: 103; LEFT: 32px; POSITION: absolute; TOP: 24px" type="file"
                name="File1" runat="server">
        </form>
    </body>
</HTML>

public class WebForm1 : System.Web.UI.Page
    {
        protected System.Web.UI.WebControls.Button Button1;
        protected System.Web.UI.HtmlControls.HtmlInputFile File1;
        protected System.Web.UI.WebControls.Button Button2;
    
        private void Page_Load(object sender, System.EventArgs e)
        {
            // Put user code to initialize the page here
        }


        Web Form Designer generated code#region Web Form Designer generated code
        override protected void OnInit(EventArgs e)
        {
            //
            // CODEGEN: This call is required by the ASP.NET Web Form Designer.
            //
            InitializeComponent();
            base.OnInit(e);
        }
        
        /**//// <summary>
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        /// </summary>
        private void InitializeComponent()
        {    
            this.Button1.Click += new System.EventHandler(this.Button1_Click);
            this.Button2.Click += new System.EventHandler(this.Button2_Click);
            this.Load += new System.EventHandler(this.Page_Load);

        }
        #endregion

        压缩#region 压缩
        private void Button1_Click(object sender, System.EventArgs e)
        {
            string []FileProperties=new string[2];            
            string fullName=this.File1.PostedFile.FileName;//C:\test\a.txt
            string destPath=System.IO.Path.GetDirectoryName(fullName);//C:\test
            //待压缩文件
            FileProperties[0]=fullName;

            //压缩后的目标文件
            FileProperties[1]= destPath +"\\"+ System.IO.Path.GetFileNameWithoutExtension(fullName)+".zip";
            ZipClass Zc=new ZipClass();
            Zc.ZipFileMain(FileProperties);

            //删除压缩前的文件
            System.IO.File.Delete(fullName);
        }

        #endregion

        解压#region 解压
        private void Button2_Click(object sender, System.EventArgs e)
        {
            string fullName=this.File1.PostedFile.FileName;//C:\test\a.zip
            //解压文件
            AttachmentUnZip.UpZip(fullName);
        }
        #endregion
    }