从Microsoft Identify Platform获取访问令牌

我已经创建了一个ASP。NET Framework应用程序使用标准模板中的Microsoft Identify Platform,并使用机密客户端获取访问令牌。我现在想使用此访问令牌调用Azure DevOps REST API。

我的设想是:

1. 打开应用程序并立即被要求登录
2. 从机密客户端获取访问令牌
3. 执行对Azure DevOps的API调用(例如GET https://dev.azure.com/{organization}/_apis/projects )

我相信我已经完成了步骤1和2(下面的代码),但当我执行API is时,它不会返回结果,只是一个HTML页面要求我登录

访问令牌从以下代码中恢复:

private async Task OnAuthorizationCodeReceived(AuthorizationCodeReceivedNotification context)
        {
            var authCode = context.Code;

            var tenantId = context.AuthenticationTicket.Identity.FindFirst("http://schemas.microsoft.com/identity/claims/tenantid").Value;
            var authority = aadInstance + tenantId;

            //string[] scopes = new string[] { "https://graph.microsoft.com/User.Read" };
            string[] scopes = new string[] { "https://app.vssps.visualstudio.com/user_impersonation" };
            //string[] scopes = new string[] { "https://graph.microsoft.com/User.Read", "https://app.vssps.visualstudio.com/user_impersonation" };

            // Get the access token from the ConfidentialClientApplication)
            IConfidentialClientApplication app = ConfidentialClientApplicationBuilder.Create(clientId)
                .WithRedirectUri(redirectUri)
                .WithClientSecret(clientSecret)
                .WithAuthority(authority)
                .Build();

            var authResult = await app.AcquireTokenByAuthorizationCode(scopes, authCode).ExecuteAsync();

            string accessToken = authResult.AccessToken;
            Debug.WriteLine($"Access Token: {accessToken}");

            //await GetProfileData(accessToken);
            await GetProjectList(accessToken);
        }

如果我运行它,我会得到访问令牌,但在API调用中使用它作为承载令牌是行不通的。调用API的方法如下:

private async Task GetProjectList(string accessToken)
        {
            // Get the Project List from the Azure DevOps API
            var httpClient = new HttpClient();
            var httpRequest = new HttpRequestMessage(HttpMethod.Get,
                "https://dev.azure.com/gp-ementris/_apis/projects");

            httpRequest.Headers.Authorization = new System.Net.Http.Headers.AuthenticationHeaderValue(
                "Bearer", accessToken);

            var response = await httpClient.SendAsync(httpRequest);

            if (response.IsSuccessStatusCode)
            {
                Debug.WriteLine(await response.Content.ReadAsStringAsync());
            }
        }

有人能帮我解释一下如何让API使用令牌吗?

谢谢