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使用MemoryStream和WebAPI返回图像

azure-blob-storage memorystream asp.net-web-api c#

TomSelleck · 技术社区 · 7 年前

我正在尝试使端点返回包含图像的MemoryStream。

这是迄今为止我掌握的代码:

控制器终结点:

[Route("v1/consumer/profile-image")]
[HttpGet]
public async Task<HttpResponseMessage> GetProfileImage(string id)
{
    var result = await ImageService.GetImage(true, id);

    var response = new HttpResponseMessage(HttpStatusCode.OK)
    {
        Content = new StreamContent(result.BlobStream)
    };

    response.Content.Headers.ContentType = new MediaTypeHeaderValue(result.ContentType);

    return response;
}

服务方法:

public async Task<ImageStream> GetImage(string profileId)
{
    var imageStream = new MemoryStream();

    var account = CloudStorageAccount.Parse(ConnectionString);
    var client = account.CreateCloudBlobClient();

    CloudBlobContainer container;
    CloudBlockBlob blob = null;

    container = client.GetContainerReference(ConsumerImageContainer);
    blob = container.GetBlockBlobReference(profileId);

    blob.FetchAttributes();

    blob.DownloadToStream(imageStream);

    return new ImageStream
    {
        BlobStream = imageStream,
        ContentType = blob.Properties.ContentType
    };
}

public class ImageStream
{
    public MemoryStream BlobStream { get; set; }
    public string ContentType { get; set; }
}

我的问题是,我似乎没有取回任何内容-我可以看到内容类型设置正确,但图像没有:

Request Headers

Request URL: https://localhost:44347/v1/consumer/profile-image
Request Method: GET
Status Code: 200 
Remote Address: [::1]:44347
Referrer Policy: no-referrer-when-downgrade

Response Headers

access-control-allow-origin: *
content-length: 0
content-type: image/jpeg
date: Mon, 09 Jul 2018 13:38:58 GMT
server: Microsoft-IIS/10.0
status: 200
x-powered-by: ASP.NET
x-sourcefiles: =?UTF-8?B?QzpcVXNlcnNcTWljaGFlbCBSeWFuXERvY3VtZW50c1xDb25zdW1lckFQSVxPcHRlemkuQ29uc3VtZXJBcGlcdjFcY29uc3VtZXJccHJvZmlsZS1pbWFnZQ==?=

1 回复 | 直到 7 年前

TomSelleck 7 年前

我需要在返回流位置之前重置它:

blob.FetchAttributes();

blob.DownloadToStream(imageStream);

imageStream.Position = 0;

return new ImageStream
{
    BlobStream = imageStream,
    ContentType = blob.Properties.ContentType
};

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