ICSharpCode.SharpZipLib 内存压缩 下载

    private void DownLoadAsZip(string folderName, string outFileName)
    {
        //取文件夹下文件，只取当前目录下文件，子文件不取
        string[] files = Directory.GetFiles(folderName);

        int folderOffset = folderName.Length + (folderName.EndsWith("\") ? 0 : 1);  //设置文件路径长度，方便后续取文件夹中文件及生成子文件夹

        MemoryStream outputMemStream = new MemoryStream();
        ZipOutputStream zipStream = new ZipOutputStream(outputMemStream);
        zipStream.SetLevel(0);

        foreach (string filename in files)
        {

            FileInfo fi = new FileInfo(filename);

            string entryName = filename.Substring(folderOffset); // Makes the name in zip based on the folder //取文件名称
            entryName = ZipEntry.CleanName(entryName); // Removes drive from name and fixes slash direction//格式化文件名称
            ZipEntry newEntry = new ZipEntry(entryName); //生成压缩文件项
            newEntry.DateTime = fi.LastWriteTime; // Note the zip format stores 2 second granularity

            newEntry.Size = fi.Length;

            zipStream.PutNextEntry(newEntry); //把压缩文件项加入 压缩文件流，应该是打开项目添加接口

            // Zip the file in buffered chunks
            // the "using" will close the stream even if an exception occurs
            byte[] buffer = new byte[4096];
            using (FileStream streamReader = File.OpenRead(filename))
            {
                StreamUtils.Copy(streamReader, zipStream, buffer); //把压缩文件项的文件流 copy 进 压缩文件流
            }
            zipStream.CloseEntry();
        }

        zipStream.IsStreamOwner = false;    // False stops the Close also Closing the underlying stream.
        zipStream.Close();          // Must finish the ZipOutputStream before using outputMemStream.

        //导出

        Response.ContentType = "application/zip";
        Response.AddHeader("content-disposition", "attachment;  filename=" + HttpUtility.UrlEncode(outFileName + ".zip", System.Text.Encoding.UTF8));
        outputMemStream.WriteTo(Response.OutputStream);
        Response.Flush();
        Response.End();

    }