c# - 如何在 Windows 窗体应用程序中使用 c Sharp 下载 azure blob 快照

Question

我正在使用 c Sharp 创建 Windows 应用程序来管理 azure blob。我能够上传 blob、下载 blob、拍摄快照、列出 blob 等。现在我的任务是下载 blob 快照(下载旧版本)文件的内容)。

我正在使用以下代码下载 blob 文件

StorageCredentials creds = new StorageCredentials(accountName, accountKey);
        CloudStorageAccount account = new CloudStorageAccount(creds, useHttps: true);

        //MessageBox.Show(sender.ToString());
        Uri myUri;
        string uri;
        var btn = sender as Button;
        uri = btn.Text;
        if (btn != null)
        {
            // MessageBox.Show(btn.Text);

            myUri = new Uri(btn.Text);
            MessageBox.Show(myUri.ToString());

        }
        // Create the blob client.
        CloudBlobClient blobClient = account.CreateCloudBlobClient();
        // Retrieve reference to a previously created container.
        CloudBlobContainer container = blobClient.GetContainerReference("samples");
        //CloudBlobContainer sampleContainer = client.GetContainerReference("samples");

        string[] parts = uri.Split('/');
        string fileName = "";

        if (parts.Length > 0)
            fileName = parts[parts.Length - 1];
        else
            fileName = uri;


        CloudBlockBlob blockBlob = container.GetBlockBlobReference(fileName);

        // Save blob contents to a file.
        try
       {


            using (var fileStream =        System.IO.File.OpenWrite(@"C:\Users\dev1\Desktop\rakshi1.jpg"))
            {
                blockBlob.DownloadToStream(fileStream);
            }
        }

        catch (Exception ex)
        {
            MessageBox.Show(ex.ToString());
        }

我使用以下代码列出特定 Blob 的快照

private void button1_Click(object sender, EventArgs e)        {            //MessageBox.Show(this.filename);            //label1            string s1= this.filename;            string accountName = "portalvhdsq3jyv0y3gccrn";            string accountKey = "VVPgjNO9V3397kOvoJRRZKtZVZaVNQP2xFPTNoWEp8zPJh4n487HVmwup498T8iufFnDS1Icu0EmUKyHg+DdkA==";            StorageCredentials creds = new StorageCredentials(accountName, accountKey);            CloudStorageAccount account = new CloudStorageAccount(creds, useHttps: true);            CloudBlobClient client = account.CreateCloudBlobClient();            CloudBlobContainer sampleContainer = client.GetContainerReference("samples");            sampleContainer.CreateIfNotExists();            CloudBlockBlob blob = sampleContainer.GetBlockBlobReference(s1);            CloudBlockBlob newBlob;            //set the metadata and save it             blob.Metadata["OriginalFilename"] = s1;            blob.SetMetadata();            //create the snapshot            newBlob = blob.CreateSnapshot();            /*             label3.Text ="Metadata['OriginalFilename'] = {0}, IsSnapshot = {1}, " + "SnapshotTime = {2}, snapshotURI = {3}"+ "   "+newBlob.Metadata["OriginalFilename"]+"  "+newBlob.IsSnapshot+" "+newBlob.SnapshotTime+" "+newBlob.SnapshotQualifiedUri;             */          //  label3.Text = "";            string text1 = "";            //retrieve all of the versions for this blob, then iterate through them            IEnumerable listOfBlobs = sampleContainer.ListBlobs(s1, true, BlobListingDetails.Snapshots);            foreach (IListBlobItem blobItem in listOfBlobs)            {                //you must cast this as a CloudBlockBlob                 //  because blobItem does not expose all of the properties                CloudBlockBlob theBlob = blobItem as CloudBlockBlob;                //Call FetchAttributes so it retrieves the metadata.                theBlob.FetchAttributes();                //print the snapshot informatino                /*  System.Diagnostics.Debug.Print("theBlob IsSnapshot = {0}, SnapshotTime = {1}, snapshotURI = {2}",                    theBlob.IsSnapshot, theBlob.SnapshotTime, theBlob.SnapshotQualifiedUri);*/               // text1 = text1 + "theBlob IsSnapshot = {0}, SnapshotTime = {1}, snapshotURI = {2}" + " @" + theBlob.IsSnapshot + " " + theBlob.SnapshotTime + " " + theBlob.SnapshotQualifiedUri;                //in case there's more than one piece of metadata,                 //  iterate through the metadata and display each key-value pair                int index = 0;                foreach (KeyValuePair kvPair in theBlob.Metadata)                {                    index++;               //     text1 = text1 + "@.MetaData {0} = {1},{2}@" + index + kvPair.Key + kvPair.Value;                }                createButton(theBlob.SnapshotQualifiedUri);           //     text1 = text1 + "@@@";                MessageBox.Show(theBlob.SnapshotQualifiedUri.ToString());            }        //    text1 = text1.Replace("@", System.Environment.NewLine);          //  label1.Text = text1;            button2.Enabled = true;        }

但我不知道如何下载每个快照

我正在使用 create_button 和 btn_click 方法更新此代码

    private void createButton(Uri uri1)        {            MessageBox.Show("hhhhhhhis");            //This block dynamically creates a Button and adds it to the form            Button btn = new Button();            btn.Name = "btn1";            btn.Location = new Point(3 + i, 14 + x);            btn.BackColor = System.Drawing.Color.White;            btn.Text = uri1.ToString();            btn.Width = 370;            btn.TextAlign = ContentAlignment.MiddleLeft;            //Hook our button up to our generic button handler            btn.Click += new EventHandler(btn_Click);            this.Controls.Add(btn);            //  textBox1.Text = textBox1.Text + "hai";            //i += 20;            x += 30;        } void btn_Click(object sender, EventArgs e)        {            StorageCredentials creds = new StorageCredentials(accountName, accountKey);            CloudStorageAccount account = new CloudStorageAccount(creds, useHttps: true);            //MessageBox.Show(sender.ToString());            Uri myUri;            string uri;            var btn = sender as Button;            uri = btn.Text;            if (btn != null)            {                // MessageBox.Show(btn.Text);                myUri = new Uri(btn.Text);                MessageBox.Show(myUri.ToString());            }            // Create the blob client.            CloudBlobClient blobClient = account.CreateCloudBlobClient();            // Retrieve reference to a previously created container.            CloudBlobContainer container = blobClient.GetContainerReference("samples");            //CloudBlobContainer sampleContainer = client.GetContainerReference("samples");            // Retrieve reference to a blob named "photo1.jpg".            string[] parts = uri.Split('/');            string fileName = "";            if (parts.Length > 0)                fileName = parts[parts.Length - 1];            else                fileName = uri;            // MessageBox.Show(fileName);            CloudBlockBlob blockBlob = container.GetBlockBlobReference(fileName);            // Save blob contents to a file.            try            {                // using (Stream outputFile = new FileStream("rakshi.jpg", FileMode.Create))                //{                //blockBlob.DownloadToStream(outputFile);                //}                using (var fileStream = System.IO.File.OpenWrite(@"C:\Users\dev1\Desktop\rakshi1.jpg"))                {                    blockBlob.DownloadToStream(fileStream);                }            }            catch (Exception ex)            {                // Console.WriteLine(ex);                MessageBox.Show(ex.ToString());            }        }

Create_button() 函数调用每个快照并显示另一个表单，其中包含与快照对应的按钮列表，当我单击按钮时，我应该下载快照。但现在它引发了一些异常

Answer 1

实际上非常简单!一旦确定 blob 的 IsSnapshot 属性为 true，您就可以简单地调用该 blob 上的下载函数。请参阅此处的示例代码:

    static void DownloadBlobSnapshot()
    {
        var cred = new StorageCredentials(accountName, accountKey);
        var account = new CloudStorageAccount(cred, true);
        var client = account.CreateCloudBlobClient();
        var container = client.GetContainerReference("snapshot-download-test");
        IEnumerable listOfBlobs = container.ListBlobs(null, true, BlobListingDetails.Snapshots);
        var downloadPath = @"D:\temp\";
        foreach (IListBlobItem blobItem in listOfBlobs)
        {
            var theBlob = blobItem as CloudBlockBlob;
            if (theBlob != null)
            {
                if (theBlob.IsSnapshot)
                {
                    theBlob.DownloadToFile(downloadPath + theBlob.Name.Replace("/", "\\"), FileMode.Create);
                }
            }
        }
    }

您不需要获取 blob 的属性或元数据。显然上面的代码非常简单。如果一个 Blob 有多个快照，并且您希望单独保存每个快照，则需要在文件名中插入 Blob 的快照日期/时间。