.NET6之MiniAPI(二十二)：HttpClient

Posted 2022-03-15 dotNET跨平台

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");