如何在干净的架构模式中正确地将 API 调用与文件存储服务分开？

我不确定你是否考虑过类路由，但我首选的处理方式是有一个模仿 UWP/Metro/etc. 从一开始就拥有的 and 框架。事实上，dotnet/runtime Github 存储库中有一个非常古老但仍然悬而未决的问题。StorageFileStorageFolder

这个想法只是让抽象基类 - 、 及其父类 - 为要使用的每个存储平台实现，从本地文件系统到 Azure blob 再到其他任何平台。StorageFileStorageFolderStorageObject

这些是基本定义：

public abstract class StorageObject 
{
    public abstract string Name { get; }
    public abstract Task RenameAsync();
    public abstract Task<StorageProperties> GetPropertiesAsync();   // would retrieve metadata like creation/access dates, size, etc.
    public abstract Task DeleteAsync();
    public abstract Task CopyAsync (StorageFolder destination);
    public abstract Task<IEnumerable<StorageObject>> GetChildrenAsync();
}

public abstract class StorageFolder : StorageObject
{
    public abstract int Files { get; }
    public abstract int Folders { get; }
    public abstract Task<StorageFile> GetFileAsync (string filename, bool createIfNotExists);
    public abstract Task<StorageFolder> GetSubfolderAsync (string subfolderName, bool createIfNotExists);

    public virtual Task<IEnumerable<StorageFile>> FindFilesAsync (string criteria, bool includeSubfolders) { ... } // default implementation would use GetChildrenAsync but be overridable for more efficient implementations
    public virtual Task<IEnumerable<StorageFolder>> FindSubfoldersAsync (string criteria, bool includeSubfolders) { ... } // same
}

public abstract class StorageFile : StorageObject
{
    public abstract Task<Stream> OpenReadAsync(bool shared = false);
    public abstract Task<Stream> OpenWriteAsync(bool shared = false); 
}

因此，例如，一个基本的（不完整的）实现将如下所示：LocalStorageFile

public class LocalStorageFile : StorageFile 
{
   private readonly string _path;

   public LocalStorageFile (string path)
   {
      _path = path;
   } 

   public override Task<Stream> OpenReadAsync(bool shared = false)
   {
      var str = File.Open(_path, FileMode.Open, FileAccess.Read, shared ? FileShare.Read : FileShare.None);
      return Task.FromResult(str);
   }

   // ...
}

然后你会这样消费它：

LocalStorageFile f = new LocalStorageFile("c:\\mypath\\file.bin");
using (var str = await f.OpenStreamForReadAsync())
{
   // do your thing
}

最重要的是，代码的其余部分都引用了基类 - 等，因此与实现完全无关。通过处理另一个高度抽象和可扩展的类，除了它之外，你不需要做任何特别的事情。当然，如果你有高度专业化的东西，你也可以子类化并从 和 返回任何你想要的东西。StorageFileStreamDisposeStreamOpenReadAsyncOpenWriteAsync

在评论中讨论后，我认为问题在于流被 处置，然后抛出一个处置对象异常。apiServicefileStorageService

此问题的可能解决方案是删除 中的语句并返回流。usingapiService

    public async Task<Stream> GetDataAsync(string url)
    {
        using (HttpResponseMessage httpResponseMessage = await httpClient.GetAsync(url))
        {
            if (httpResponseMessage.IsSuccessStatusCode)
            {
                return await httpResponseMessage.Content.ReadAsStreamAsync();
            }
        }
    }

然后，您可以通过以下方式使用它：

string url = "<some_url>";
Stream result = await apiService.GetDataAsync(url);

using(result)
{
    string path ="<some_path>";
    await fileStorageService.CreateFileAsync(path, result);
}