从设备上传文件到云

我们之前的文章都是介绍如何在设备上向云发送消息，这包括通过发送遥测数据(), 或者上报属性的更改等等，但是还有一种场景，我们需要向云发送文件，例如我们在使用视频监控设备进行监控的时候，监控设备会定期生成相同大小的视频文件，这些视频文件是我们的监控数据，视频文件一般会比较大，不适合通过消息上传到云，我们可以使用结合提供的文件上传功能来应对这个场景。

要从设备上向云上传文件，需要如下几个步骤：

在里配置。

在设备应用中初始化文件上传的功能

利用初始化的结果取回链接字符串。

使用结合得到的链接字符串完成上传文件。

我们先在中配置

创建好和的资源，最好将这两个资源创建在同一个资源组里，并且在同一个Azure区域。

登录, 找到你的资源，然后从左侧的菜单里选择 , 如下图：

这个界面的配置还是很直接的：

在处选择之前已经准备好的Storage, 并选择好需要放置的容器。

在处配置文件上传之后是否发送上传成功的通知，后台应用可以监听这个事件，并及时处理上传的文件。

在处配置当我们初始化上传功能之后，生成的的的过期时间，默认是1个小时，取值范围在小时。

在处配置文件上传成功后发送的通知消息过期时间是多少，默认是一个小时，取值范围是 小时。

在处配置在同一时间内可以传递多少条文件上传成功的消息，取值范围是 条。

在处配置和之间的认证方式，默认是通过

到这里就配置好了，那么我们接下来可以开始新建两个应用快速测试一下。

上传文件的设备应用

首先创建一个控制台的应用：

注意

是使用打开当前的项目目录，另外需要注意的是，本章的代码可以在这个URL找到：https://github.com/hylinux/azure-iot-hub-examples/tree/main/DeviceUploadFileDemo

主要的代码实现是在文件, 其中最重要的代码部分是：

初始化文件上传：

const string filePath = "TestPayload.txt";

using var fileStreamSource = new FileStream(filePath, FileMode.Open);

var fileName = Path.GetFileName(fileStreamSource.Name);

Console.WriteLine($"Uploading file ");

var fileUploadTime = Stopwatch.StartNew();

var fileUploadSasUriRequest = new FileUploadSasUriRequest

{

BlobName = fileName

};

// Note: GetFileUploadSasUriAsync and CompleteFileUploadAsync will use HTTPS as protocol regardless of the DeviceClient protocol selection.

Console.WriteLine("Getting SAS URI from IoT Hub to use when uploading the file...");

FileUploadSasUriResponse sasUri = await _deviceClient.GetFileUploadSasUriAsync(fileUploadSasUriRequest);

Uri uploadUri = sasUri.GetBlobUri();

Console.WriteLine($"Successfully got SAS URI () from IoT Hub");

在取得了连接的 连接字符串，然后使用如下的代码进行上传：

var blockBlobClient = new BlockBlobClient(uploadUri);

await blockBlobClient.UploadAsync(fileStreamSource, new BlobUploadOptions());

如果上传失败，也可以生成一个上传失败的通知：

Console.WriteLine($"Failed to upload file to Azure Storage using the Azure Storage SDK due to ");

var failedFileUploadCompletionNotification = new FileUploadCompletionNotification

{

// Mandatory. Must be the same value as the correlation id returned in the sas uri response

CorrelationId = sasUri.CorrelationId,

// Mandatory. Will be present when service client receives this file upload notification

IsSuccess = false,

// Optional, user-defined status code. Will be present when service client receives this file upload notification

StatusCode = 500,

// Optional, user defined status description. Will be present when service client receives this file upload notification

StatusDescription = ex.Message

};

// Note that this is done even when the file upload fails. IoT Hub has a fixed number of SAS URIs allowed active

// at any given time. Once you are done with the file upload, you should free your SAS URI so that other

// SAS URIs can be generated. If a SAS URI is not freed through this API, then it will free itself eventually

// based on how long SAS URIs are configured to live on your IoT Hub.

await _deviceClient.CompleteFileUploadAsync(failedFileUploadCompletionNotification);

Console.WriteLine("Notified IoT Hub that the file upload failed and that the SAS URI can be freed");

fileUploadTime.Stop();

上传成功了之后也发送一个通知：

Console.WriteLine("Successfully uploaded the file to Azure Storage");

var successfulFileUploadCompletionNotification = new FileUploadCompletionNotification

{

// Mandatory. Must be the same value as the correlation id returned in the sas uri response

CorrelationId = sasUri.CorrelationId,

// Mandatory. Will be present when service client receives this file upload notification

IsSuccess = true,

// Optional, user defined status code. Will be present when service client receives this file upload notification

StatusCode = 200,

// Optional, user-defined status description. Will be present when service client receives this file upload notification

StatusDescription = "Success"

};

await _deviceClient.CompleteFileUploadAsync(successfulFileUploadCompletionNotification);

Console.WriteLine("Notified IoT Hub that the file upload succeeded and that the SAS URI can be freed.");

fileUploadTime.Stop();

Console.WriteLine($"Time to upload file: .");

以上就是主要的步骤了，可以从代码上下载测试代码测试一下。

注意

实例代码中使用了包, 发现这个包在上有一个bug, 在使用来运行并且在参数上使用短参数的形式，会报错。但是可以发布应用再运行就没有这个问题了。

运行:

到这里我们就完成了文件上传了，下面我们接着测试监听文件上传的事件。

监听文件上传完成的通知

创建一个控制台应用：

然后使用编辑器打开文件'Program.cs', 主要内容如下：

using Microsoft.Azure.Devices;

ServiceClient serviceClient;

string connectionString = "";

Console.WriteLine("Receive file upload notifications\n");

serviceClient = ServiceClient.CreateFromConnectionString(connectionString);

ReceiveFileUploadNotificationAsync(serviceClient);

Console.WriteLine("Press Enter to exit\n");

Console.ReadLine();

async void ReceiveFileUploadNotificationAsync(ServiceClient serviceClient)

{

var notificationReceiver = serviceClient.GetFileNotificationReceiver();

Console.WriteLine("\nReceiving file upload notification from service");

while (true)

{

var fileUploadNotification = await notificationReceiver!.ReceiveAsync();

if (fileUploadNotification == null) continue;

Console.ForegroundColor = ConsoleColor.Yellow;

Console.WriteLine("Received file upload notification: ",

string.Join(", ", fileUploadNotification.BlobName));

Console.ResetColor();

await notificationReceiver!.CompleteAsync(fileUploadNotification);

}

}

运行该代码，就可以看到：