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Thursday, January 23, 2014

Windows Azure: Upload and Download Functionality- upload/download image to blob

Following class is useful to download or upload image from blob. Provide necessary parameters to function.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI.WebControls;
using Microsoft.WindowsAzure.Storage;
using Microsoft.WindowsAzure.Storage.Auth;
using Microsoft.WindowsAzure.Storage.Blob;
using System.Configuration;
using Microsoft.WindowsAzure;
using System.IO;
using Microsoft.WindowsAzure.ServiceRuntime;

namespace AzureDemo
{
    public class AzureBlobManager
    {
        public string uploadFilesToAzureBlob(FileUpload PostedFile, string FileName, string containerName, Guid userid)
        {
            string blobURLs = string.Empty;
            try
            {
                // Retrieve storage account from connection string.
                CloudStorageAccount storageAccount = CloudStorageAccount.Parse(
    ConfigurationManager.ConnectionStrings["StorageConnectionString"].ConnectionString);

                // Create the blob client.
                CloudBlobClient blobClient = storageAccount.CreateCloudBlobClient();

                // Retrieve a reference to a container.              
                CloudBlobContainer container = blobClient.GetContainerReference(containerName);

                // Create the container if it doesn't already exist.
                container.CreateIfNotExists();

                if (PostedFile.PostedFile.ContentLength > 0)
                {
                    System.IO.Stream inputStream = PostedFile.PostedFile.InputStream;
                    inputStream.Position = 0;

                    byte[] myBinary = new byte[PostedFile.PostedFile.ContentLength];
                    //PostedFile.InputStream.Read(myBinary, 0, (int)PostedFile.ContentLength);
                    using (var binaryReader = new System.IO.BinaryReader(inputStream))
                    {
                        myBinary = binaryReader.ReadBytes(PostedFile.PostedFile.ContentLength);
                    }
                    // Retrieve reference to a blob named "myblob".
                    CloudBlockBlob blockBlob = container.GetBlockBlobReference(string.Concat(userid, "_", PostedFile.FileName));

                    // Create or overwrite the "myblob" blob with contents from a local file.                      
                    //blockBlob.UploadFromStream(PostedFile.PostedFile.InputStream);

                    blockBlob.UploadFromStream(new System.IO.MemoryStream(myBinary));
                    // blockBlob.UploadFromStream(PostedFile.PostedFile.InputStream);

                    blobURLs = blockBlob.Uri.ToString();
                }
            }
            catch (Exception ex)
            {
                //HandleException.HandleExceptionLog(ex);
            }
            return blobURLs;
        }


//Directly reads from blob and sends it to user
        public void DownloadFileFromBlob(string fileName,string containerName)
        {
            CloudStorageAccount account = CloudStorageAccount.Parse(ConfigurationManager.ConnectionStrings["StorageConnectionString"].ConnectionString);

            CloudBlobClient blobClient = account.CreateCloudBlobClient();
            CloudBlobContainer container = blobClient.GetContainerReference(containerName);
            CloudBlockBlob blob = container.GetBlockBlobReference(fileName);
            MemoryStream memStream = new MemoryStream();
            blob.DownloadToStream(memStream);

            HttpContext.Current.Response.ContentType = blob.Properties.ContentType;
            HttpContext.Current.Response.AddHeader("Content-Disposition", "Attachment; filename=" + fileName.ToString());
            HttpContext.Current.Response.AddHeader("Content-Length", blob.Properties.Length.ToString());
            HttpContext.Current.Response.BinaryWrite(memStream.ToArray());
        }
    }
}