C#批量压缩文件打包为zip文件下载

using System;
using System.Collections.Generic;
using System.IO;
using System.Threading;
using ICSharpCode.SharpZipLib.Zip;
namespace Lib
{
    /// <summary>
    /// 文件压缩、解压缩
    /// </summary>
    public class FileCompression
    {
        /// <summary>
        /// 构造函数
        /// </summary>
        public FileCompression()
        {
        }
        #region 加密、压缩文件
        /// <summary>
        /// 压缩文件
        /// </summary>
        /// <param name="fileNames">要打包的文件列表</param>
        /// <param name="GzipFileName">目标文件名</param>
        /// <param name="CompressionLevel">压缩品质级别（0~9）</param>
        /// <param name="SleepTimer">休眠时间（单位毫秒）</param>     
        public static void Compress(List<FileInfo> fileNames, string GzipFileName, int CompressionLevel, int SleepTimer)
        {
            ZipOutputStream s = new ZipOutputStream(File.Create(GzipFileName));
            try
            {
                s.SetLevel(CompressionLevel);   //0 - store only to 9 - means best compression
                foreach (FileInfo file in fileNames)
                {
                    FileStream fs = null;
                    try
                    {
                        fs = file.Open(FileMode.Open, FileAccess.ReadWrite);
                    }
                    catch
                    { continue; }
                    //  方法二，将文件分批读入缓冲区
                    byte[] data = new byte[2048];
                    int size = 2048;
                    ZipEntry entry = new ZipEntry(Path.GetFileName(file.Name));
                    entry.DateTime = (file.CreationTime > file.LastWriteTime ? file.LastWriteTime : file.CreationTime);
                    s.PutNextEntry(entry);
                    while (true)
                    {
                        size = fs.Read(data, 0, size);
                        if (size <= 0) break;
                        s.Write(data, 0, size);
                    }
                    fs.Close();
                    Thread.Sleep(SleepTimer);
                }
            }
            finally
            {
                s.Finish();
                s.Close();
            }
        }
        #endregion
        #region 解密、解压缩文件
        /// <summary>
        /// 解压缩文件
        /// </summary>
        /// <param name="GzipFile">压缩包文件名</param>
        /// <param name="targetPath">解压缩目标路径</param>       
        public static void Decompress(string GzipFile, string targetPath)
        {
            //string directoryName = Path.GetDirectoryName(targetPath + "\\") + "\\";
            string directoryName = targetPath;
            if (!Directory.Exists(directoryName)) Directory.CreateDirectory(directoryName);//生成解压目录
            string CurrentDirectory = directoryName;
            byte[] data = new byte[2048];
            int size = 2048;
            ZipEntry theEntry = null;
            using (ZipInputStream s = new ZipInputStream(File.OpenRead(GzipFile)))
            {
                while ((theEntry = s.GetNextEntry()) != null)
                {
                    if (theEntry.IsDirectory)
                    {// 该结点是目录
                        if (!Directory.Exists(CurrentDirectory + theEntry.Name)) Directory.CreateDirectory(CurrentDirectory + theEntry.Name);
                    }
                    else
                    {
                        if (theEntry.Name != String.Empty)
                        {
                            //解压文件到指定的目录
                            using (FileStream streamWriter = File.Create(CurrentDirectory + theEntry.Name))
                            {
                                while (true)
                                {
                                    size = s.Read(data, 0, data.Length);
                                    if (size <= 0) break;
                                    streamWriter.Write(data, 0, size);
                                }
                                streamWriter.Close();
                            }
                        }
                    }
                }
                s.Close();
            }
        }
        #endregion
    }
}

protected void butDerive_Click(object sender, EventArgs e)  
{  
    //先压缩文件  
    string checkboxNameValues = Request.Form["checkboxImg"];  
    if (checkboxNameValues != "" && checkboxNameValues != null)  
    {  
        string[] values = checkboxNameValues.Split(',');  
        List<FileInfo> fileList = new List<FileInfo>();  
        for (int i = 0; i < values.Length; i++)  
        {  
            string path = Server.MapPath(values[i]);  
            FileInfo fi = new FileInfo(path);  
            fileList.Add(fi);  
        }  
        if (!Directory.Exists(Server.MapPath("~/ZipFile/")))  
        {  
            Directory.CreateDirectory(Server.MapPath("~/ZipFile/"));  
        }  
          
        //调用方法  
        string zipFilePath = "ZipFile/" + DateTime.Now.ToString("yyyyMMddHHmmssffff") + ".zip";  
        string zipServerFilepath = Server.MapPath("~/" + zipFilePath);  
        Lib.FileCompression.Compress(fileList, zipServerFilepath, 5, 5);  
    }  
}