开发时经常会遇到需要压缩文件的需求，利用C#的开源组件ICSharpCode.SharpZipLib，

就可以很容易的实现压缩和解压缩功能。

主要是操作（Zip）压缩算法

上代码：

压缩文件

        /// <summary>  
        /// 压缩指定文件生成ZIP文件  
        /// </summary>  
        /// <param name="topDirName">顶层文件夹名称</param>  
        /// <param name="fileNamesToZip">待压缩文件</param>  
        /// <param name="ZipedFileName">ZIP文件</param>  
        /// <param name="CompressionLevel">压缩比</param>  
        /// <param name="password">密码</param>  
        /// <param name="comment">压缩文件注释文字</param>  
        public static void ZipFile
            (
            string topDirName,  //顶层文件夹名称 
            string fileNameToZip,  //待压缩文件  
            string ZipedFileName,   //ZIP文件   
            int CompressionLevel,    //压缩比   
            string password,    //密码   
            string comment   //压缩文件注释文字  
            )

        {
            var ls = new List<string> { fileNameToZip };
            ZipFile(topDirName, ls.ToArray(), ZipedFileName, CompressionLevel, password, comment);
        }
        /// <summary>  
        /// 压缩指定多个文件生成ZIP文件  
        /// </summary>  
        /// <param name="topDirName">顶层文件夹名称</param>  
        /// <param name="fileNamesToZip">待压缩文件列表</param>  
        /// <param name="ZipedFileName">ZIP文件</param>  
        /// <param name="CompressionLevel">压缩比</param>  
        /// <param name="password">密码</param>  
        /// <param name="comment">压缩文件注释文字</param>  
        public static void ZipFile
            (
            string topDirName,  //顶层文件夹名称  
            string[] fileNamesToZip,  //待压缩文件列表  
            string ZipedFileName,   //ZIP文件   
            int CompressionLevel,    //压缩比  9
            string password,    //密码   ""
            string comment   //压缩文件注释文字  ""
            )
        {
            using (var s = new ZipOutputStream(File.Open(ZipedFileName, FileMode.Create)))
            {
                if (password != null && password.Length > 0)
                    s.Password = password;

                if (comment != null && comment.Length > 0)
                    s.SetComment(comment);

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

                foreach (string file in fileNamesToZip)
                {
                    using (FileStream fs = File.OpenRead(topDirName + file))
                    {   //打开待压缩文件  
                        byte[] buffer = new byte[fs.Length];
                        fs.Read(buffer, 0, buffer.Length);      //读取文件流  
                        ZipEntry entry = new ZipEntry(file);    //新建实例   
                        entry.DateTime = DateTime.Now;
                        entry.Size = fs.Length;
                        s.PutNextEntry(entry);
                        s.Write(buffer, 0, buffer.Length);
                    }
                }
                s.Finish();
            }


        }

解压缩文件：

/// <summary>  
        /// 解压缩ZIP文件到指定文件夹  
        /// </summary>  
        /// <param name="zipfileName">ZIP文件</param>  
        /// <param name="UnZipDir">解压文件夹</param>  
        /// <param name="password">压缩文件密码</param>  
        public static void UnZipFile(string zipfileName, string UnZipDir, string password)
        {
            using (ZipInputStream s = new ZipInputStream(File.OpenRead(zipfileName)))
            {
                if (!string.IsNullOrWhiteSpace(password))
                    s.Password = password;
                try
                {
                    ZipEntry theEntry;
                    while ((theEntry = s.GetNextEntry()) != null)
                    {
                        string directoryName = Path.GetDirectoryName(UnZipDir);
                        string pathname = Path.GetDirectoryName(theEntry.Name);
                        string fileName = Path.GetFileName(theEntry.Name);

                        //生成解压目录   
                        pathname = pathname.Replace(":", "$");//处理压缩时带有盘符的问题  
                        directoryName = directoryName + "\\" + pathname;
                        Directory.CreateDirectory(directoryName);

                        if (fileName != String.Empty)
                        {
                            //解压文件到指定的目录  
                            using (var streamWriter = File.Create(directoryName + "\\" + 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.Flush();
                            }
                        }
                    }
                }
                catch (Exception eu)
                {
                    throw eu;
                }
            }
        }