c# - 在内存中创建 Zip 存档，并从 web api 返回它

Question

所以我正在尝试创建一个 zip 存档并从我的 web api 返回它。从角度 2 站点调用 Controller 。目前已创建 zip 文件，但当我打开它时，我收到一条无效消息。最初我在 using 语句中有流，但不得不更改它，因为它们在请求完成之前被处理。

我需要的是创建 zip 文件，将 csv 文件添加到其内容中。然后返回 zip 文件。但是 zip 文件总是无效的。我已经阅读过需要处理 zip 存档以便写入其内容，但我不确定实现此目的的最佳方法是什么。感谢您的指导。

public async Task<IHttpActionResult> ExportReport(int id, ReportModel report)
    {
        try
        {
            var result = await ReportGenerationService.ExportReportForId(id, report.Page, report.PageSize, report.SortField, report.SortDir, report.SearchTerm, report.StartDate, report.EndDate, report.UserId, report.TeamId, report.SelectedDateItem);
            if (result != null)
            {

                var compressedFileStream = new MemoryStream();

                var zipArchive = new ZipArchive(compressedFileStream, ZipArchiveMode.Update, false);

                var zipEntry = zipArchive.CreateEntry("textExport.csv");
                var origionalFileSteam = new MemoryStream(result.ExportToBytes());
                var zipEntryStream = zipEntry.Open();
                origionalFileSteam.CopyTo(zipEntryStream);


                var response = new HttpResponseMessage(HttpStatusCode.OK) {Content = new StreamContent(compressedFileStream)};
                response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");
                response.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment")
                {
                    FileName = "Export.zip"
                };

                var t = compressedFileStream.CanRead;
                return ResponseMessage(response);

            }

            return NotFound();
        }
        catch (Exception ex)
        {
            return InternalServerError(ex);
        }
    }

对 using 语句的响应:

有一次我将所有内容都包含在 using 语句中，但响应会失败，因为流已被释放。您可以在下面看到这一点。

public async Task<IHttpActionResult> ExportReport(int id, ReportModel report)
    {
        try
        {
            var result = await ReportGenerationService.ExportReportForId(id, report.Page, report.PageSize, report.SortField, report.SortDir, report.SearchTerm, report.StartDate, report.EndDate, report.UserId, report.TeamId, report.SelectedDateItem);
            if (result != null)
            {

                var compressedFileStream = new MemoryStream();
                var zipArchive = new ZipArchive(compressedFileStream, ZipArchiveMode.Update, false);

                        //Create a zip entry for each attachment
                    var zipEntry = zipArchive.CreateEntry("textExport.csv");

                    //Get the stream of the attachment
                    using (var originalFileStream = new MemoryStream(result.ExportToBytes()))
                    using (var zipEntryStream = zipEntry.Open()) {
                        //Copy the attachment stream to the zip entry stream
                        originalFileStream.CopyTo(zipEntryStream);
                    }
                    compressedFileStream.Position = 0;

                    var response = new HttpResponseMessage(HttpStatusCode.OK) {Content = new StreamContent(compressedFileStream)};
                    response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");
                    response.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment")
                    {
                        FileName = "Export.zip"
                    };

                    return ResponseMessage(response);
            }

            return NotFound();
        }
        catch (Exception ex)
        {
            return InternalServerError(ex);
        }
    }

Answer 1

您缺少一些 using(){} block 。

确保以正确的顺序关闭 originalFileSteam、zipEntryStream 和 zipArchive。

为了确定，重置内存流。我不知道是否需要这样做，但不会有什么坏处。

//using (var compressedFileStream = new MemoryStream())
var compressedFileStream = new MemoryStream();

using (var zipArchive = new ZipArchive(...)) 
{
        //Create a zip entry for each attachment
        var zipEntry = zipArchive.CreateEntry("textExport.csv");

        //Get the stream of the attachment
        using (var originalFileStream = new MemoryStream(result.ExportToBytes()))
        using (var zipEntryStream = zipEntry.Open()) 
        {
            //Copy the attachment stream to the zip entry stream
            originalFileStream.CopyTo(zipEntryStream);
        }
}

//compressedFileStream .Position = 0;
var responseBytes =new MemoryStream(compressedFileStream.ToArray());

var response = new HttpResponseMessage(HttpStatusCode.OK) {Content = new StreamContent(responseBytes )};
response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");

return ResponseMessage(response);