输入文字在Azure存储的文件 [英] Write text to a file in Azure storage

问题描述

我在Azure存储account.Now上传文本文件中，在我的辅助角色，我需要做的是在每次运行时，它将从数据库中的一些内容，而且这些内容必须在上传写文本文件，具体而言，每次文本文件的内容应该与一些新的内容覆盖。

I have a text file uploaded in my Azure storage account.Now, in my worker role , what i need to do is every time it is run, it fetches some content from Database, and that content must be written in the Uploaded text file, specifically , each time the content of Text file should be overwritten with some new content.

这里，他们给一个方法到一个文本文件上传到您的存储，并删除file.But我不想这样做，只是需要修改已每次present文本文件。

Here, they have given a way to upload a text file to your storage and also delete a file.But i don't want to do that, need to just MODIFY the already present text file each time.

推荐答案

我假设你指的是存储在Windows Azure中的BLOB文件。如果是这样的话：一个blob不是一个文件系统;它只是一个存储数据的地方（和文件的概念是有点做作 - 它只是......存储在一堆块的BLOB）。

I'm assuming you're referring to storing a file in a Windows Azure blob. If that's the case: A blob isn't a file system; it's just a place to store data (and the notion of a file is a bit artificial - it's just... a blob stored in a bunch of blocks).

要修改文件，你需要下载并保存到本地磁盘，修改它（再次，在本地磁盘上），然后做一个上传。在这几个想法：

To modify the file, you would need to download it and save it to local disk, modify it (again, on local disk), then do an upload. A few thoughts on this:

• 为此，你应该你的工人角色的配置中分配一个本地磁盘。该盘将是一个逻辑磁盘，你的虚拟机上运行的机器内的本地物理磁盘上创建。换句话说，它会为这种类型的使用进行附加存储和完美。


• 您的虚拟机实例和存储之间的带宽是<击>每核的100Mbps。因此，抓住一个10MB的文件，同时在一个小实例，将采取可能一秒钟。在一个XL，或许围绕一个十分之一秒。的真快，并与VM系列（A，D，G）和大小不同而不同。


• 因为你的文件是Blob存储，如果你觉得这样的倾向这样做（或有此需要），你可以采取快照上传更新版本之前。快照是像链接列表来存储的数据块。而且也没有成本的快照，直到有一天，你进行了更改现有数据（现在你必须重新块presenting新旧数据）。一个很好的方式对一个blob按BLOB基础上斑点的preserve版本（和它的琐碎删除快照）。

• For this purpose, you should allocate a local disk within your worker role's configuration. This disk will be a logical disk, created on a local physical disk within the machine your vm is running on. In other words, it'll be attached storage and perfect for this type of use.
• The bandwidth between your vm instance and storage is 100Mbps per core. So, grabbing a 10MB file, while on a Small instance, would take maybe a second. On an XL, maybe around a tenth of a second. really fast, and varies with VM series (A, D, G) and size.
• Because your file is in blob storage, if you felt so inclined to do so (or had the need for this), you could take a snapshot prior to uploading an updated version. Snapshots are like link-lists to your stored data blocks. And there's no cost to snapshots until, one day, you make a change to existing data (and now you'd have blocks representing both old and new data). An excellent way to preserve versions of a blob on a blob-by-blob basis (and it's trivial to delete snapshots).

只是为了确保此下载/修改/上传模式是明确的，这里有一个很简单的例子（我只是在Visual Studio中键入这件事很快，但还没有测试它只是想说明这一点。）：

Just to make sure this download/modify/upload pattern is clear, here's a very simple example (I just typed this up quickly in Visual Studio but haven't tested it. Just trying to illustrate the point):

        // initial setup
        var acct = CloudStorageAccount.Parse(CloudConfigurationManager.GetSetting("StorageConnectionString"));
        var client = acct.CreateCloudBlobClient();

        // what you'd call each time you need to update a file stored in a blob
        var blob = client.GetContainerReference("mycontainer").GetBlockBlobReference("myfile.txt");
        using (var fileStream = System.IO.File.OpenWrite(@"path\myfile.txt"))
        {
            blob.DownloadToStream(fileStream);
        }

        // ... modify file...

        // upload modified file
        using (var fileStream = System.IO.File.OpenWrite(@"path\myfile.txt"))
        {
            blob.UploadFromStream(fileStream);
        }

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