从内存流C#创建Zip文件

Question

基本上用户应该能够点击一个链接并下载多个pdf文件.但Catch是我无法在服务器或任何地方创建文件.一切都必须在记忆中.

我能够创建内存流和Response.Flush()它作为PDF格式,但如何在不创建文件的情况下压缩多个内存流.

这是我的代码:

    Response.ContentType = "application/zip";

            // If the browser is receiving a mangled zipfile, IIS Compression may cause this problem. Some members have found that
            // Response.ContentType = "application/octet-stream" has solved this. May be specific to Internet Explorer.
            Response.AppendHeader("content-disposition", "attachment; filename=\"Download.zip\"");
            Response.CacheControl = "Private";
            Response.Cache.SetExpires(DateTime.Now.AddMinutes(3)); // or put a timestamp in the filename in the content-disposition                

            byte[] abyBuffer = new byte[4096];

            ZipOutputStream outStream = new ZipOutputStream(Response.OutputStream);

            outStream.SetLevel(3);

            #region Repeat for each Memory Stream
            MemoryStream fStream = CreateClassroomRoster();// This returns a memory stream with pdf document

            ZipEntry objZipEntry = new ZipEntry(ZipEntry.CleanName("ClassroomRoster.pdf"));

            objZipEntry.DateTime = DateTime.Now;

            objZipEntry.Size = fStream.Length;

            outStream.PutNextEntry(objZipEntry);

            int count = fStream.Read(abyBuffer, 0, abyBuffer.Length);

            while (count > 0)
            {
                outStream.Write(abyBuffer, 0, count);

                count = fStream.Read(abyBuffer, 0, abyBuffer.Length);

                if (!Response.IsClientConnected)
                {
                    break;
                }

                Response.Flush();
            }

            fStream.Close();
            #endregion

            outStream.Finish();
            outStream.Close();

            Response.Flush();
            Response.End();

这会创建一个zip文件,但里面没有文件

我正在使用iTextSharp.text - 使用ICSharpCode.SharpZipLib.Zip创建pdf - 用于压缩

谢谢,卡维塔

Answer 1

此链接描述了如何使用SharpZipLib从MemoryStream创建zip:https://github.com/icsharpcode/SharpZipLib/wiki/Zip-Samples#wiki-anchorMemory.使用这个和iTextSharp,我能够压缩在内存中创建的多个PDF文件.

这是我的代码:

        MemoryStream outputMemStream = new MemoryStream();
        ZipOutputStream zipStream = new ZipOutputStream(outputMemStream);

        zipStream.SetLevel(3); //0-9, 9 being the highest level of compression
        byte[] bytes = null;

        // loops through the PDFs I need to create
        foreach (var record in records)
        {
            var newEntry = new ZipEntry("test" + i + ".pdf");
            newEntry.DateTime = DateTime.Now;

            zipStream.PutNextEntry(newEntry);

            bytes = CreatePDF(++i);

            MemoryStream inStream = new MemoryStream(bytes);
            StreamUtils.Copy(inStream, zipStream, new byte[4096]);
            inStream.Close();
            zipStream.CloseEntry();

        }

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

        outputMemStream.Position = 0;

        return File(outputMemStream.ToArray(), "application/octet-stream", "reports.zip");

CreatePDF方法:

private static byte[] CreatePDF(int i)
    {
        byte[] bytes = null;
        using (MemoryStream ms = new MemoryStream())
        {
            Document document = new Document(PageSize.A4, 25, 25, 30, 30);
            PdfWriter writer = PdfWriter.GetInstance(document, ms);
            document.Open();
            document.Add(new Paragraph("Hello World " + i));
            document.Close();
            writer.Close();
            bytes = ms.ToArray();
        }
        return bytes;

    }