幾種使用IHttpClientFactory方法
微軟在.NET Framework 4.5的時候推出HttpClient，以取代原本的WebClient，但是卻有一些連線端耗盡及DNS異動問題。所以微軟又推出了HttpClientFactory來改善這些情況。
關於HttpClient效能議題及HttpClinetFactory介紹，網上已有許多說明，這邊就僅純記錄官方HttpClientFactory使用方法，再補充附加參數的方法
環境
直接使用HttpClientFactory
無論使用何種方式，都必須在Startup.cs中的ConfigureServices方法中註冊HttpClient
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public void ConfigureServices(IServiceCollection services)
{
services.AddHttpClient();
services.AddRazorPages();
}
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在要使用的類別上，使用相依性插入 (DI)
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public class LineService : ILineService
{
private readonly IHttpClientFactory _httpClientFactory;
public LineService(IHttpClientFactory httpClientFactory)
{
_httpClientFactory = httpClientFactory;
}
public async Task PushMessage()
{
// 建立 HttpClient 實例
var httpClient = _httpClientFactory.CreateClient();
httpClient.BaseAddress = new Uri("https://api.line.me");
httpClient.DefaultRequestHeaders.Add("authorization", "Bearer {CannelAccessToken}");
var message = "Fake Message Object";
var json = JsonConvert.SerializeObject(message);
HttpContent contentPost = new StringContent(json, Encoding.UTF8, "application/json");
await httpClient.PostAsync("/v2/bot/message/push", contentPost);
}
}
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具名用戶端(Named Clients)
在Startup.cs註冊通用基礎設定值
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public void ConfigureServices(IServiceCollection services)
{
services.AddHttpClient("Line", c =>
{
c.BaseAddress = new Uri("https://api.line.me");
// ChannelAccessToken 請自行替換
c.DefaultRequestHeaders.Add("authorization", "{ChannelAccessToken}");
});
services.AddRazorPages();
}
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使用定義的名稱建立 HttpClient 實例
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public class LineService : ILineService
{
private readonly IHttpClientFactory _httpClientFactory;
public LineService(IHttpClientFactory httpClientFactory)
{
_httpClientFactory = httpClientFactory;
}
public async Task PushMessage()
{
// 使用定義的名稱建立 HttpClient 實例
var httpClient = _httpClientFactory.CreateClient("Line");
var message = "Fake Message Object";
var json = JsonConvert.SerializeObject(message);
HttpContent contentPost = new StringContent(json, Encoding.UTF8, "application/json");
await httpClient.PostAsync("/v2/bot/message/push", contentPost);
}
}
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具型別用戶端(Typed Client)
使用Typed Client方法，就是在類別中使用HttpClient，而非IHttpClientFactory介面，這時候預設值有兩種方法設置。
在自訂類別中的建構子設定預設值
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public void ConfigureServices(IServiceCollection services)
{
services.AddHttpClient<ILineService, LineService>();
services.AddRazorPages();
}
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public class LineService : ILineService
{
private readonly HttpClient _httpClient;
public LineService(HttpClient httpClient)
{
httpClient.BaseAddress = new Uri("https://api.line.me");
httpClient.DefaultRequestHeaders.Add("authorization", "Bearer {CannelAccessToken}");
_httpClient = httpClient;
}
public async Task PushMessage()
{
var message = "Fake Message Object";
var json = JsonConvert.SerializeObject(message);
HttpContent contentPost = new StringContent(json, Encoding.UTF8, "application/json");
await _httpClient.PostAsync("/v2/bot/message/push", contentPost);
}
}
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public void ConfigureServices(IServiceCollection services)
{
services.AddHttpClient<ILineService, LineService>(x =>
{
x.BaseAddress = new Uri("https://api.line.me");
x.DefaultRequestHeaders.Add("authorization", "Bearer {CannelAccessToken}");
});
services.AddRazorPages();
}
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public class LineService : ILineService
{
private readonly HttpClient _httpClient;
public LineService(HttpClient httpClient)
{
_httpClient = httpClient;
}
public async Task PushMessage()
{
var message = "Fake Message Object";
var json = JsonConvert.SerializeObject(message);
HttpContent contentPost = new StringContent(json, Encoding.UTF8, "application/json");
await _httpClient.PostAsync("/v2/bot/message/push", contentPost);
}
}
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參考
在 ASP.NET Core 中使用 IHttpClientFactory 發出 HTTP 要求
https://docs.microsoft.com/zh-tw/aspnet/core/fundamentals/http-requests?view=aspnetcore-3.1#named-clients