异步后流关闭

Question

我有一个 ASP.NET 核心应用程序，需要向 Microsoft 认知服务发送流（流由客户端发布）以获取 ID。然后将相同的流发送到azure blob进行备份，文件名应该是从认知服务接收到的ID。

但在 faceServiceClient 使用后，MemoryStream ms 似乎已关闭：在第二个“ms.Position = 0”语句中出现错误，即“无法访问已关闭的流”。

public static async Task CreatPerson(string _key, HttpRequest _req)
{
    var faceServiceClient = new FaceServiceClient(_key);
    using (MemoryStream ms = new MemoryStream())
    {
        _req.Body.CopyTo(ms);
        ms.Position = 0;
        var facesTask = faceServiceClient.AddFaceToFaceListAsync("himlens", ms);
        //init azure blob
        CloudStorageAccount storageAccount = CloudStorageAccount.Parse(AZURE_STORE_CONN_STR);
        CloudBlobClient blobClient = storageAccount.CreateCloudBlobClient();
        CloudBlobContainer container = blobClient.GetContainerReference("xxx");
        var faces = await facesTask;
        var blob = container.GetBlockBlobReference(faces.PersistedFaceId.ToString());

        ms.Position = 0;//Error Here
        await blob.UploadFromStreamAsync(ms);
    }
}

我对此感到困惑，有人可以帮我解决这个问题吗？

谢谢！

Answer 1

ms.Position = 0;//此处出错

要轻松修复它，您可以创建一个新的 MemoryStream 实例并从 ms 复制值。然后您可以将其上传到您的 blob 存储。以下代码供您参考。

using (MemoryStream ms = new MemoryStream())
{
    _req.Body.CopyTo(ms);
    ms.Position = 0;
    //new code which I added 
    MemoryStream ms2 = new MemoryStream();
    ms.CopyTo(ms2);
    ms.Position = 0;

    var facesTask = faceServiceClient.AddFaceToFaceListAsync("himlens", ms);
    //init azure blob
    CloudStorageAccount storageAccount = CloudStorageAccount.Parse(AZURE_STORE_CONN_STR);
    CloudBlobClient blobClient = storageAccount.CreateCloudBlobClient();
    CloudBlobContainer container = blobClient.GetContainerReference("xxx");
    var faces = await facesTask;
    var blob = container.GetBlockBlobReference(faces.PersistedFaceId.ToString());
    //Code which I modified
    ms2.Position = 0;
    await blob.UploadFromStreamAsync(ms2);
}