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c# - Netcore 2.1 ServiceCollection 添加通用类型的 HttpClients 未按预期解析

问题描述

我遇到了 Netcore 2.1 向 ServiceCollection 添加多个通用类型的HttpClient的问题。这没有按预期工作，它给了我奇怪的结果。

考虑我的测试

var services = new ServiceCollection();

services.AddHttpClient<IHttpGenericClientFactory<test1>, HttpGenericClientFactory<test1>>(client =>
{
    client.BaseAddress = new Uri("https://test1.com/");
});

services.AddHttpClient<IHttpGenericClientFactory<test2>, HttpGenericClientFactory<test2>>(client =>
{
    client.BaseAddress = new Uri("https://test2.com/");
});

现在尝试解决每个服务时

var provider = services.BuildServiceProvider();

var service1 = provider.GetService<IHttpGenericClientFactory<test1>>();
var service2 = provider.GetService<IHttpGenericClientFactory<test2>>();

当我检查service1.BaseAddress值是“ https://test2.com/ ”并且service2.BaseAddress也是“ https://test2.com/ ”。无论我尝试了什么，该服务总是解析或引用已添加的最后一个通用类型服务。这是框架中的错误吗？任何人都知道为什么这不能正常工作？这绝对与通用类型的 http 客户端有关。

我的通用类和接口

public interface IHttpGenericClientFactory<out T3>
{
    HttpClient HttpClient { get; set; }
    Task<T1> Get<T1, T2>(T2 request, string path);
}

public class HttpGenericClientFactory<T3> : IHttpGenericClientFactory<T3>
{
    public HttpClient HttpClient { get; set; }

    public HttpGenericClientFactory(HttpClient httpClient) => this.HttpClient = httpClient;

    public async Task<T1> Get<T1,T2>(T2 request, string path)
    {
        var response = await HttpClient.GetAsync(path);
        response.EnsureSuccessStatusCode();
        return await response.Content.ReadAsAsync<T1>();
    }
}

标签： c#asp.net-coreasp.net-core-mvcasp.net-core-2.0asp.net-core-webapi

解决方案

您无法根据泛型类型参数的泛型类型参数的差异进行解析。我可以推荐的最好的事情是创建具体的派生，然后您可以明确引用：

public class Test1ClientFactory : HttpGenericClientFactory<Test1> {}

public class Test2ClientFactory : HttpGenericClientFactory<Test2> {}

然后：

services.AddHttpClient<Test1ClientFactory>(client =>
{
    client.BaseAddress = new Uri("https://test1.com/");
});

services.AddHttpClient<Test2ClientFactory>(client =>
{
    client.BaseAddress = new Uri("https://test2.com/");
});

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