问题描述
我有Asp.Net Core WebApi.我根据 HttpClientFactory发出Http请求模式.这是我的示例代码:
I have Asp.Net Core WebApi. I am making Http requests according to HttpClientFactory pattern. Here is my sample code:
public void ConfigureServices(IServiceCollection services)
{
...
services.AddHttpClient<IMyInterface, MyService>();
...
}
public class MyService: IMyInterface
{
private readonly HttpClient _client;
public MyService(HttpClient client)
{
_client = client;
}
public async Task CallHttpEndpoint()
{
var request = new HttpRequestMessage(HttpMethod.Get, "www.customUrl.com");
var response = await _client.SendAsync(request);
...
}
}
我想通过动态代理实现发送请求.这基本上意味着我可能需要为每个请求更改代理.到目前为止，我发现了2种解决方案，对我来说，其中的一种似乎不是很好:
I want to implement sending requests through dynamic proxy. This basically means that I might need to change proxy with each request. As for now I find out 2 approuces, non of which seems good to me:
1.拥有一个像这样的静态代理:
1.Have a static proxy like this:
public void ConfigureServices(IServiceCollection services)
{
...
services.AddHttpClient<IMyInterface, MyService>().ConfigurePrimaryHttpMessageHandler(() =>
{
return new HttpClientHandler
{
Proxy = new WebProxy("http://127.0.0.1:8888"),
UseProxy = true
};
});
...
}
但是在这种方法中，每个服务只能有一个代理.
But I can only have single proxy per service in this approach.
2.将每个请求处置HttpClient:
2.Dispose HttpClient with each request:
HttpClientHandler handler = new HttpClientHandler()
{
Proxy = new WebProxy("http://127.0.0.1:8888"),
UseProxy = true,
};
using(var client = new HttpClient(handler))
{
var request = new HttpRequestMessage(HttpMethod.Get, "www.customUrl.com");
var response = await client.SendAsync(request);
...
}
但是以这种方式，我违反了HttpClientFactory模式，并且可能导致应用程序性能出现问题，如以下文章
But in this way I violate HttpClientFactory pattern and it might cause issues to application performance as stated in following article
还有第三种方法可以在不重新创建HttpClient的情况下动态更改代理吗?
Is there a third way where I could change proxy dinamically without re-creating HttpClient?
推荐答案
无法更改HttpClientHandler的任何属性，也不能在其后为现有的HttpClient分配新版本的HttpClientHandler.被实例化.这样，就不可能为特定的HttpClient创建动态代理:您只能指定一个代理.
There is no way to change the any of the properties of HttpClientHandler or to assign a new version of HttpClientHandler to an existing HttpClient after it is instantiated. As such, it is then impossible to have a dynamic proxy for a particular HttpClient: you can only specify one proxy.
实现此目的的正确方法是改为使用命名客户端，并为每个代理端点定义一个客户端.然后，您需要注入IHttpClientFactory并选择要使用的代理之一，请求实现该代理的命名客户端.
The correct way to achieve this is to use named clients, instead, and define a client for each proxy endpoint. Then, you'll need to inject IHttpClientFactory and pick one of the proxies to use, requesting the named client that implements that.
services.AddHttpClient("MyServiceProxy1").ConfigurePrimaryHttpMessageHandler(() =>
{
return new HttpClientHandler
{
Proxy = new WebProxy("http://127.0.0.1:8888"),
UseProxy = true
};
});
services.AddHttpClient("MyServiceProxy2").ConfigurePrimaryHttpMessageHandler(() =>
{
return new HttpClientHandler
{
Proxy = new WebProxy("http://127.0.0.1:8889"),
UseProxy = true
};
});
...
然后:
public class MyService : IMyInterface
{
private readonly HttpClient _client;
public MyService(IHttpClientFactory httpClientFactory)
{
_client = httpClientFactory.CreateClient("MyServiceProxy1");
}
public async Task CallHttpEndpoint()
{
var request = new HttpRequestMessage(HttpMethod.Get, "www.customUrl.com");
var response = await _client.SendAsync(request);
...
}
}
这篇关于具有HttpClientFactory实现的动态代理的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！