正确使用.net-core瞬态服务的IHttpClientFactory

Question

我正在研究在我的asp.net核心应用程序中使用IHttpClientFactory来调用外部app。我见过一些在服务类的构造函数中创建客户端工厂的示例。然后，该类的方法调用该客户端工厂来生成HttpClient的实例，以发出Http请求。如以下示例代码所示：

public class MyTransientService: IMyService
{
    private readonly IHttpClientFactory _clientFactory;

    public MyTransientService(
        IHttpClientFactory clientFactory
    )
    {
        _clientFactory = clientFactory;
    }

    public async Task<MyData> GetData()
    {
        //construct the request
        var httpClient = _clientFactory.CreateClient();
        var response = await client.SendAsync(request);
        ...
    }
}

如果服务在startup.cs中注册为瞬态服务，那么每次调用该服务时，不是都会生成一个新的HttpClientFactory实例吗？每个请求一个新的HttpClientFactory？那么，以下不是使用工厂的更有效的方法吗？

public class MyTransientService: IMyService
    {
        private readonly HttpClient _client;
    
        public MyTransientService(
            HtpClient client
        )
        {
            _client = client;
        }
    
        public async Task<MyData> GetData()
        {
            Uri uri = new Uri(StaticUtils.AddQueryString(url, props));
            var response = await _client.SendAsync(request);
            ...
        }
    }

Answer 1

我会认为自己创建HttpClient是一种糟糕的做法，在self中，你可以控制创建了多少。如果MyTransientService是暂时的，您将最终创建大量套接字连接(每个实例/请求一个套接字连接)创建HttpClient以供重用。

看一下键入的客户端：https://docs.microsoft.com/en-us/dotnet/architecture/microservices/implement-resilient-applications/use-httpclientfactory-to-implement-resilient-http-requests

public void ConfigureServices(IServiceCollection services)
{
    services.AddHttpClient("hello", c =>
    {
        c.BaseAddress = new Uri("http://localhost:5000");
    })
    .AddTypedClient<MyTransientService>();

    services.AddControllers();
}

public class MyTransientService: IMyService
{
    private readonly HttpClient _client;

    public MyTransientService(
        HtpClient client
    )
    {
        _client = client;
    }

    public async Task<MyData> GetData()
    {
        Uri uri = new Uri(StaticUtils.AddQueryString(url, props));
        var response = await _client.SendAsync(request);
        ...
    }
}