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我想要完成的任務是創建Web API服務，以便將文件上載到Azure存儲。同時，我想有一個反映實際上傳進度的進度指示器。經過一番調查和研究，我發現了兩個重要的事情：Web API - 上傳到Azure存儲時取得進展
首先是，我必須手動分割文件分割成塊，並將其上傳異步使用PutBlockAsync方法從Microsoft.WindowsAzure.Storage.dll。
其次，是我必須在我的Web API服務中以流模式而不是緩衝模式接收文件。
所以，到現在爲止，我有以下實現：
UploadController.cs
using System.Configuration;
using System.Net;
using System.Net.Http;
using System.Threading.Tasks;
using System.Web.Http;
using Microsoft.WindowsAzure.Storage;
using Microsoft.WindowsAzure.Storage.Blob;
using WebApiFileUploadToAzureStorage.Infrastructure;
using WebApiFileUploadToAzureStorage.Models;
namespace WebApiFileUploadToAzureStorage.Controllers
{
public class UploadController : ApiController
{
[HttpPost]
public async Task<HttpResponseMessage> UploadFile()
{
if (!Request.Content.IsMimeMultipartContent("form-data"))
{
return Request.CreateResponse(HttpStatusCode.UnsupportedMediaType,
new UploadStatus(null, false, "No form data found on request.", string.Empty, string.Empty));
}
var streamProvider = new MultipartAzureBlobStorageProvider(GetAzureStorageContainer());
var result = await Request.Content.ReadAsMultipartAsync(streamProvider);
if (result.FileData.Count < 1)
{
return Request.CreateResponse(HttpStatusCode.BadRequest,
new UploadStatus(null, false, "No files were uploaded.", string.Empty, string.Empty));
}
return Request.CreateResponse(HttpStatusCode.OK);
}
private static CloudBlobContainer GetAzureStorageContainer()
{
var storageConnectionString = ConfigurationManager.AppSettings["AzureBlobStorageConnectionString"];
var storageAccount = CloudStorageAccount.Parse(storageConnectionString);
var blobClient = storageAccount.CreateCloudBlobClient();
blobClient.DefaultRequestOptions.SingleBlobUploadThresholdInBytes = 1024 * 1024;
var container = blobClient.GetContainerReference("photos");
if (container.Exists())
{
return container;
}
container.Create();
container.SetPermissions(new BlobContainerPermissions
{
PublicAccess = BlobContainerPublicAccessType.Container
});
return container;
}
}
}
MultipartAzureBlobStorageProvider.cs
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Net.Http;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.WindowsAzure.Storage.Blob;
namespace WebApiFileUploadToAzureStorage.Infrastructure
{
public class MultipartAzureBlobStorageProvider : MultipartFormDataStreamProvider
{
private readonly CloudBlobContainer _blobContainer;
public MultipartAzureBlobStorageProvider(CloudBlobContainer blobContainer) : base(Path.GetTempPath())
{
_blobContainer = blobContainer;
}
public override Task ExecutePostProcessingAsync()
{
const int blockSize = 256 * 1024;
var fileData = FileData.First();
var fileName = Path.GetFileName(fileData.Headers.ContentDisposition.FileName.Trim('"'));
var blob = _blobContainer.GetBlockBlobReference(fileName);
var bytesToUpload = (new FileInfo(fileData.LocalFileName)).Length;
var fileSize = bytesToUpload;
blob.Properties.ContentType = fileData.Headers.ContentType.MediaType;
blob.StreamWriteSizeInBytes = blockSize;
if (bytesToUpload < blockSize)
{
var cancellationToken = new CancellationToken();
using (var fileStream = new FileStream(fileData.LocalFileName, FileMode.Open, FileAccess.ReadWrite))
{
var upload = blob.UploadFromStreamAsync(fileStream, cancellationToken);
Debug.WriteLine($"Status {upload.Status}.");
upload.ContinueWith(task =>
{
Debug.WriteLine($"Status {task.Status}.");
Debug.WriteLine("Upload is over successfully.");
}, TaskContinuationOptions.OnlyOnRanToCompletion);
upload.ContinueWith(task =>
{
Debug.WriteLine($"Status {task.Status}.");
if (task.Exception != null)
{
Debug.WriteLine("Task could not be completed." + task.Exception.InnerException);
}
}, TaskContinuationOptions.OnlyOnFaulted);
upload.Wait(cancellationToken);
}
}
else
{
var blockIds = new List<string>();
var index = 1;
long startPosition = 0;
long bytesUploaded = 0;
do
{
var bytesToRead = Math.Min(blockSize, bytesToUpload);
var blobContents = new byte[bytesToRead];
using (var fileStream = new FileStream(fileData.LocalFileName, FileMode.Open))
{
fileStream.Position = startPosition;
fileStream.Read(blobContents, 0, (int)bytesToRead);
}
var manualResetEvent = new ManualResetEvent(false);
var blockId = Convert.ToBase64String(Encoding.UTF8.GetBytes(index.ToString("d6")));
Debug.WriteLine($"Now uploading block # {index.ToString("d6")}");
blockIds.Add(blockId);
var upload = blob.PutBlockAsync(blockId, new MemoryStream(blobContents), null);
upload.ContinueWith(task =>
{
bytesUploaded += bytesToRead;
bytesToUpload -= bytesToRead;
startPosition += bytesToRead;
index++;
var percentComplete = (double)bytesUploaded/fileSize;
Debug.WriteLine($"Percent complete: {percentComplete.ToString("P")}");
manualResetEvent.Set();
});
manualResetEvent.WaitOne();
} while (bytesToUpload > 0);
Debug.WriteLine("Now committing block list.");
var putBlockList = blob.PutBlockListAsync(blockIds);
putBlockList.ContinueWith(task =>
{
Debug.WriteLine("Blob uploaded completely.");
});
putBlockList.Wait();
}
File.Delete(fileData.LocalFileName);
return base.ExecutePostProcessingAsync();
}
}
}
我還啓用了流模式this博客文章提示。這種方法效果很好，因爲該文件已成功上載到Azure存儲。然後，當我使用XMLHttpRequest（並訂閱進度事件）撥打此服務的電話時，我看到該指示器非常迅速地移至100％。如果一個5MB文件需要大約1分鐘才能上傳，我的指標只需1秒即可完成。所以問題可能在於服務器通知客戶端上傳進度的方式。對此有何想法？謝謝。
================================更新1 ============ =======================
這是我用它來調用服務的JavaScript代碼
function uploadFile(file, index, uploadCompleted) {
var authData = localStorageService.get("authorizationData");
var xhr = new XMLHttpRequest();
xhr.upload.addEventListener("progress", function (event) {
fileUploadPercent = Math.floor((event.loaded/event.total) * 100);
console.log(fileUploadPercent + " %");
});
xhr.onreadystatechange = function (event) {
if (event.target.readyState === event.target.DONE) {
if (event.target.status !== 200) {
} else {
var parsedResponse = JSON.parse(event.target.response);
uploadCompleted(parsedResponse);
}
}
};
xhr.open("post", uploadFileServiceUrl, true);
xhr.setRequestHeader("Authorization", "Bearer " + authData.token);
var data = new FormData();
data.append("file-" + index, file);
xhr.send(data);
}
Giorgios，你如何訂閱進度事件？ –