C# Httpclient 单例在多个客户端/用户上具有相同的身份验证标头

Question

我有一个调用 API 的 Azure 函数，我在启动依赖注入中将 HttpClient 作为单例，这样我就可以在我的承包商上调用它。我下面的代码调用两个具有相同身份验证标头的 API。

public class MyClass : IMyClass
{
        private readonly HttpClient _httpClient;
        public MyClass(HttpClient httpClient)
        {
            _httpClient = httpClient;
        }
        
        public void test(string OAuthToken)
        {
            _httpClient.DefaultRequestHeaders.Accept.Clear();
            _httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
            _httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", OAuthToken);

            // 1st API
            string firstApi = $"https://GetSometthingFirst.com/processes?api-version=5.0";
            var GetFirst = _httpClient.GetAsync(firstApi).Result;

             // add delay 5 secs
             Thread.Sleep(5000);
    

            // 2nd API
            string secondApi = $"https://GetSometthingSecond.com/processes?api-version=5.0";
            var content = new StringContent(GetFirst.ToString(), Encoding.UTF8, "application/json");

            var result = _httpClient.PostAsync(secondApi, content).Result;
        }

}

在上面的代码中，我有两个 API 调用，它们使用相同的

DefaultRequestHeader

。由于它是单例，因此该函数可以由多个用户使用不同的

OAthToken

作为参数进行调用，并共享同一个 HttpClient 实例。我是否需要像这样刷新默认标头，以便其他线程不会受到影响？

public void test(string OAuthToken)
        {
            _httpClient.DefaultRequestHeaders.Accept.Clear();
            _httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
            _httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", OAuthToken);

            // 1st API
            string firstApi = $"https://GetSometthingFirst.com/processes?api-version=5.0";
            var GetFirst = _httpClient.GetAsync(firstApi).Result;

            _httpClient.DefaultRequestHeaders.Accept.Clear();
            _httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
            _httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", OAuthToken);

             // add delay 5 secs
             Thread.Sleep(5000)

            // 2nd API
            string secondApi = $"https://GetSometthingSecond.com/processes?api-version=5.0";
            var content = new StringContent(GetFirst.ToString(), Encoding.UTF8, "application/json");

            var result = _httpClient.PostAsync(secondApi, content).Result;
        }

Answer 1

官方文档建议您使用HttpClientFactory来实现弹性HTTP请求。它使 HttpClient 实例的管理更加容易。