.net - 如何创建用于依赖的Singleton注入(inject)Azure存储客户端和容器

我有一个类，该类具有执行Azure存储功能的方法，目前，每次调用StorageContainer，BlobClient和Container时，我都会创建它:

private readonly IAzureStorageConfig _config;

public SaveImageBlob(IAzureStorageConfig config)
{
    _config = config;
}

public async Task<T> ExecuteAsync(ImageSaveInput input)
{

    //get the storage account from the connection string
    CloudStorageAccount storageAccount = CloudStorageAccount.Parse(_config.ConnectionString);

    //instantiate the client
    CloudBlobClient blobClient = storageAccount.CreateCloudBlobClient();

    //set the container
    CloudBlobContainer container = blobClient.GetContainerReference(_config.ImagesContainerName);

    //... do things and stuff
}

现在，我想将其从SaveImageBlob.ExecuteAsync方法中剔除，并将依赖项注入到类中，因此Azure存储项仅实例化一次。

我目前有这样的界面:

namespace Domain.Interfaces
{
    public interface IAzureStorage
    {
        CloudStorageAccount StorageAccount { get; }

        CloudBlobClient BlobClient { get; }

        CloudBlobContainer Container { get; }
    }
}

现在，我对如何实现该接口一无所知。

一旦实现了接口，我想我将把SaveImageBlob.ExecuteAsync方法更改为此:

private readonly IAzureStorageConfig _config;
private readonly IAzureStorage _storage;

public SaveImageBlob(IAzureStorageConfig config,
                     IAzureStorage storage)
{
    _config = config;
    _storage = storage;
}

public async Task<T> ExecuteAsync(ImageSaveInput input)
{

    //now, since I don't have to create an instance of the storageAccount, blobClient, and container, I can just access them from _storage
    //create the blockBlob
    CloudBlockBlob blockBlob = _storage.Container.GetBlockBlobReference(input.BlobUrl);

    //... do things and stuff with a Stream (doesn't really matter)

    //upload the blob
    blockBlob.UploadFromStreamAsync(stream);

    //do more things and stuff and return something
}

我只需要知道如何实现该接口，就可以将AzureStorage类作为Singleton输入到SaveImageBlob。没关系，但是为了后代，我将Autofac用于DI。

最佳答案

单例的基本思想包括一个私有静态实例变量和一个公共静态Instance属性，该属性会线程安全地检查是否设置了实例变量，如果没有设置，则将其设置，然后返回它。

using Microsoft.WindowsAzure.Storage;
using Microsoft.WindowsAzure.Storage.Blob;
using System;

public sealed class AzureStorage
{
    private static volatile AzureStorage instance;
    private static object syncRoot = new Object();

    public CloudStorageAccount StorageAccount { get; private set; }
    public CloudBlobClient BlobClient { get; private set; }
    public CloudBlobContainer Container { get; private set; }

    private AzureStorage()
    {
        StorageAccount = CloudStorageAccount.Parse(_config.ConnectionString);

        //instantiate the client
        BlobClient = StorageAccount.CreateCloudBlobClient();

        //set the container
        Container = BlobClient.GetContainerReference(_config.ImagesContainerName);

    }

    public static AzureStorage Instance
    {
        get
        {
            if (instance == null)
            {
                lock (syncRoot)
                {
                    if (instance == null)
                        instance = new AzureStorage();
                }
            }

            return instance;
        }
    }
}

留给读者的练习是提供配置。