无法设置内容类型答案

【问题标题】：can not able to set Content type无法设置内容类型
【发布时间】：2019-08-05 06:40:39
【问题描述】：

我正在尝试将图像保存在 azure blob 存储中。我通过代码设置了内容类型，如下但它正在准备但没有上传。我该怎么办？

文件上传代码：

[HttpPost("ListFiles")]
public async Task<List<string>> InsertFile(List<IFormFile> asset)
{
    try
    {
        var urlList = new List<string>();
        foreach (var op in asset)
        {


            if (CloudStorageAccount.TryParse(_config.Value.StorageConnection, out CloudStorageAccount storageAccount))
            {
                CloudBlobClient blobClient = storageAccount.CreateCloudBlobClient();

                CloudBlobContainer container = blobClient.GetContainerReference(_config.Value.Container);

                  var postedFileExtension = Path.GetExtension(op.FileName);
                var img = $@"{Guid.NewGuid()}" + postedFileExtension;
                CloudBlockBlob blockBlob = container.GetBlockBlobReference(img);
                CloudBlockBlob cloudBlockBlob = container.GetBlockBlobReference(img);
                cloudBlockBlob.Properties.ContentType = op.ContentType;
                await blockBlob.UploadFromStreamAsync(op.OpenReadStream());
                var blob = container.GetBlockBlobReference(img);

                urlList.Add(blob.Uri.AbsoluteUri);
            }

        }
        return urlList;
    }
    catch (Exception e)
    {
        throw e;
    }
}

【问题讨论】：

您正在更新记录的第二个引用的属性，但不保存更改。重用blockBlob 并将其设置为ContentType 的值或保存cloudBlockBlob。

标签： azure azure-blob-storage

【解决方案1】：

要在上传 blob 时设置内容类型，只需在调用上传方法之前设置 ContentType 属性即可。下面是我的测试代码，你可以试试。

static void Main(string[] args)
    {
        String strorageconn = "storage string";
        CloudStorageAccount storageacc = CloudStorageAccount.Parse(strorageconn);

        //Create Reference to Azure Blob
        CloudBlobClient blobClient = storageacc.CreateCloudBlobClient();

        CloudBlobContainer container = blobClient.GetContainerReference("test");

        CloudBlockBlob blockBlob = container.GetBlockBlobReference("test.jpg");

        blockBlob.Properties.ContentType = "image/jpg";

        using (var filestream = System.IO.File.OpenRead(@"D:\Picture\test.jpg"))
        {

            blockBlob.UploadFromStream(filestream);

        }
    }

并使用存储资源管理器读取属性，结果如下。

【讨论】：

【解决方案2】：

你正在使用

var postedFileExtension = Path.GetExtension(op.FileName);
var img = $@"{Guid.NewGuid()}" + postedFileExtension;

CloudBlockBlob blockBlob = container.GetBlockBlobReference(img);
CloudBlockBlob cloudBlockBlob = container.GetBlockBlobReference(img);
cloudBlockBlob.Properties.ContentType = op.ContentType;

await blockBlob.UploadFromStreamAsync(op.OpenReadStream());
var blob = container.GetBlockBlobReference(img);

您正在设置变量的 ContentType 属性，但未将此更改提交给 Azure。将代码更新为：

var postedFileExtension = Path.GetExtension(op.FileName);
var img = $@"{Guid.NewGuid()}" + postedFileExtension;

CloudBlockBlob blockBlob = container.GetBlockBlobReference(img);  
blockBlob.Properties.ContentType = op.ContentType;

await blockBlob.UploadFromStreamAsync(op.OpenReadStream());
var blob = container.GetBlockBlobReference(img);

Console.WriteLine(blob.Properties.ContentType); // Output the contentType

【讨论】：