Azure Blob存储 - 使用文件流/内存流显示PDF

Question

我已经建立了一个Azure Blob Storage以上传/下载文件。请参考此链接配置您的存储连接字符串。

ProcessAsync(Folderpath, rows.Item("FileName"), rows.Item("Extension")).GetAwaiter().GetResult()
System.IO.File.Move(Folderpath + "\" + rows.Item("FileName"), AchivePath + "\" + rows.Item("FileName"))
WriteToLog("Extracted File : " + rows.Item("FileName") + " ", "")
DownloadBlobSnapshot(rows.Item("FileName"), rows.Item("Extension")).GetAwaiter().GetResult()

目前，我能够将文件存储在我的桌面上。如何使用 .net MVC 平台和 Using 和 MemoryStream/FileStream 将文件保存并显示出来？

或者，是否有更好的方法来完成这个任务？

编辑 1：（基于 Ivan 的答案）

Private Shared Async Function DownloadBlobSnapshot(FileName As String, Extension As String) As Task

Dim storageAccount As CloudStorageAccount
Dim storageConnectionString As String = ConfigurationManager.AppSettings("StorageConnectionString")
Dim accountName As String = myaccountname
Dim accountKey As String = myaccountkey
Dim cred = New StorageCredentials(accountName, accountKey)
Dim account = New CloudStorageAccount(cred, True)
Dim client = account.CreateCloudBlobClient()
Dim container = client.GetContainerReference(FileName.Replace(Extension, ""))
Dim listOfBlobs As IEnumerable = container.ListBlobs(Nothing, True, BlobListingDetails.Snapshots)

If CloudStorageAccount.TryParse(storageConnectionString, storageAccount) Then
   For Each item In listOfBlobs
       Dim blockBlob As CloudBlockBlob = container.GetBlockBlobReference((CType(item, CloudBlockBlob)).Name)
       blockBlob.DownloadToStream(Response.OutputStream)
   Next
       //ToDO
        End If
End Function

但是我意识到Response在Shared函数中不可用。

- PartTimeNerd

---

只是想澄清一下，您想在MVC页面中显示.pdf文件吗？您的.pdf文件是存储在本地还是Blob存储中？ - Ivan Glasenberg

@IvanYang 是的。我先将它存储在本地，然后上传到 Blob 存储中。之后，我通过下载相同的文件并将其存储在不同的文件夹中来测试它。 - PartTimeNerd

我想知道，如果你想要在MVC页面中显示存储在Blob存储中的.pdf文件，对吗？ - Ivan Glasenberg

@IvanYang，没错。 - PartTimeNerd

如果使用DownloadToStream方法，那应该很容易，你可以参考我下面的回答。一分钟后。 - Ivan Glasenberg

请告诉我是否有任何问题 :) - Ivan Glasenberg

Answer 1

你可以使用 DownloadToStream。

以下是示例代码（asp.net mvc项目）：

        public ActionResult DownloadFile()
        {
            CloudStorageAccount storageAccount = new CloudStorageAccount(new StorageCredentials("your_account", "your_key"),true);
            CloudBlobClient client = storageAccount.CreateCloudBlobClient();
            CloudBlobContainer blobContainer = client.GetContainerReference("t11");
            CloudBlockBlob blob = blobContainer.GetBlockBlobReference("ss22.pdf");

            blob.DownloadToStream(Response.OutputStream);

            return new EmptyResult();
        }

更新1：上传vb.net mvc项目的截图：

- Ivan Glasenberg

---

这是一个vb.net项目吗？我不熟悉:(。但是你是否创建了一个vb.net mvc项目并在xxxcontroller.vb中编写代码？我创建了一个vb.net mvc项目，响应正常。稍后，我会在我的答案中添加截图。 - Ivan Glasenberg

可能是因为我的方法声明问题，似乎我们不能在“shared”方法中使用“Response”。 - PartTimeNerd

不确定，因为我不熟悉vb，如果是c#，我可以进行更多的调查 :)。 - Ivan Glasenberg

Answer 2

如果你遇到了和我一样的问题，请看这里。

Function DownloadBlobSnapshot(FileName As String, Extension As String) As ActionResult

    Dim storageAccount As CloudStorageAccount
    Dim storageConnectionString As String = ConfigurationManager.AppSettings("StorageConnectionString")
    Dim accountName As String = myaccountname
    Dim accountKey As String = myaccountkey
    Dim cred = New StorageCredentials(accountName, accountKey)
    Dim account = New CloudStorageAccount(cred, True)
    Dim client = account.CreateCloudBlobClient()
    Dim container = client.GetContainerReference("myfilename")
    Dim fileStream As New MemoryStream
    fileStream.Position = 0
    Dim listOfBlobs As IEnumerable = container.ListBlobs(Nothing, True, BlobListingDetails.Snapshots)

    Try
        If CloudStorageAccount.TryParse(storageConnectionString, storageAccount) Then
            For Each item In listOfBlobs
                Dim blockBlob As CloudBlockBlob = container.GetBlockBlobReference((CType(item, CloudBlockBlob)).Name)
                blockBlob.DownloadToStream(fileStream)
                Response.Clear()
                Response.ContentType = "application/force-download"
                Response.AddHeader("content-disposition", "inline; filename=name_you_file.pdf")
                Response.BinaryWrite(fileStream.ToArray)
                Response.End()

                Return New FileStreamResult(fileStream, "application/pdf")

            Next

        End If
    Catch ex As Exception

    End Try

End Function

更新日期：2018年11月29日

Function DownloadBlobSnapshot(FilePath As String, LabCompany As String, FileName As String) As ActionResult

    Dim storageAccount As CloudStorageAccount
    Dim cloudBlobContainer As CloudBlobContainer = Nothing
    Dim sourceFile As String = Nothing
    Dim destinationFile As String = Nothing
    Dim storageConnectionString As String = (CASAuthentication.Decrypt(Configs.BlobConnectionString))
    Dim url As String = ""
    Dim sasToken As String = ""

    If CloudStorageAccount.TryParse(storageConnectionString, storageAccount) Then
        Try

            Dim cloudBlobClient As CloudBlobClient = storageAccount.CreateCloudBlobClient()

            cloudBlobContainer = cloudBlobClient.GetContainerReference(LabCompany.ToLower)
            If cloudBlobContainer.Exists() Then
                Dim cloudBlockBlob As CloudBlockBlob = cloudBlobContainer.GetBlockBlobReference((FileName))
                If cloudBlockBlob.Exists Then
                    url = cloudBlockBlob.Uri.AbsoluteUri()

                    Dim sharedPolicy As SharedAccessBlobPolicy = New SharedAccessBlobPolicy() With {
            .SharedAccessExpiryTime = DateTime.UtcNow.AddMinutes(Integer.Parse(ConfigurationManager.AppSettings("PDFTimeOut"))),
            .Permissions = SharedAccessBlobPermissions.Read Or SharedAccessBlobPermissions.Write
        }

                    sasToken = cloudBlockBlob.GetSharedAccessSignature(sharedPolicy)

                End If
            End If

                Return Json(New With {.success = True, .url = url + sasToken}, JsonRequestBehavior.AllowGet)

        Catch ex As Exception
            Return Json(New With {.success = False, .message = ex.ToString}, JsonRequestBehavior.AllowGet)
        Finally

        End Try

    Else
        Return Json(New With {.success = False, .message = "Failed to receive report data. Please try again later."}, JsonRequestBehavior.AllowGet)
    End If

End Function

使用ajax显示

var tabledata =  {mydata: data}
    $.ajax({
        cache: false,
        type: "POST",
        url: "/Home/DownloadBlobSnapshot",
        contentType: "application/json; charset=utf-8",
        data: JSON.stringify(tabledata),
        success: function (result) {
            var e = result.url
            //e.substr(0, e.lastIndexOf("/"))
            e = "http://docs.google.com/viewer?url=" + encodeURIComponent(e) + "&embedded=true";
            popitup(e);
        },

        error: function () {

        }
    });

- PartTimeNerd