说明：本篇不是说明HttpClient怎么使用，而以分享在asp.net core mini api框架下，HttpClient的引入和使用方式。

我们在业务开发中，免不了调用三方的服务，这时就会用到HttpClient，在早期的asp.net core框架中，一般是通过new HttpClient来实现对三方的请求，现在，可以通过HttPClientFactory来实现，这样的好处是可以池化连接，节省资源。

基础使用方法很简单：

var builder = WebApplication.CreateBuilder(args);builder.Services.AddHttpClient();var app = builder.Build();app.MapGet("/test", async (IHttpClientFactory clientFactory) =>{var client = clientFactory.CreateClient();var content = await client.GetStringAsync("https://www.google.com");});app.Run();

当项目中有多个三方服务请求，为了区分各个三方服务，可以采用命名方式

var builder = WebApplication.CreateBuilder(args);builder.Services.AddHttpClient("Google", httpClient =>
{httpClient.BaseAddress = new Uri("https://www.google.com/");
});
builder.Services.AddHttpClient("BaiDu", httpClient =>
{httpClient.BaseAddress = new Uri("https://www.baidu.com/");
});
var app = builder.Build();app.MapGet("/testgoogle", async (IHttpClientFactory clientFactory) =>{var googleClient = clientFactory.CreateClient("Google");return await googleCclient.GetStringAsync("search?q=桂素伟");});
app.MapGet("/testbaidu", async (IHttpClientFactory clientFactory) =>
{var baiduClient = clientFactory.CreateClient("BaiDu");return await lient .GetStringAsync("s?wd=桂素伟");
});
app.Run();

还可以项目中每个服务的请求各自封装，各用各的HttpClient:

var builder = WebApplication.CreateBuilder(args);builder.Services.AddHttpClient<IGoogleService, GoogleService>();
builder.Services.AddHttpClient<IBaiDuService, BaiDuService>(httpClient =>
{httpClient.BaseAddress = new Uri("https://www.baidu.com/");
});var app = builder.Build();app.MapGet("/testgoogle", async (IGoogleService google) =>{return await google.GetContentAsync();});
app.MapGet("/testbaidu", async (IBaiDuService baidu) =>
{return await baidu.GetContentAsync();
});
app.Run();interface IGoogleService
{Task<string> GetContentAsync();
}
class GoogleService : IGoogleService
{private readonly HttpClient _httpClient;public GoogleService(HttpClient httpClient){_httpClient = httpClient;_httpClient.BaseAddress = new Uri("https://www.google.com/");}public async Task<string> GetContentAsync(){return await _httpClient.GetStringAsync("search?q=桂素伟");}
}
interface IBaiDuService
{Task<string> GetContentAsync();
}
class BaiDuService : IBaiDuService
{private readonly HttpClient _httpClient;public BaiDuService(HttpClient httpClient){_httpClient = httpClient;}public async Task<string> GetContentAsync(){return await _httpClient.GetStringAsync("s?wd=桂素伟");}
}