Microsoft Graph access token refresh-CodePudding

I am writing an application that uses the "OAuth 2.0 client credentials grant flow" to get an access token for calling the Microsoft Graph API. The application authenticates as itself, not on behalf of a signed in user.

I based my code off of this

Then you may have some ideas that you insist on using refresh the expired token process, then what you only can do is generate an access token first and save the token with its expired time in some place, and using the access token as the http request header and calling graph api. Then the code should like this, but I don't think you're willing to using this kind of code, you may also refer to this document for more details:

var scopes = new[] { "https://graph.microsoft.com/.default" };
var tenantId = "tenant_name.onmicrosoft.com";
var clientId = "your_azuread_clientid";
var clientSecret = "corresponding_client_secret";
var clientSecretCredential = new ClientSecretCredential(
    tenantId, clientId, clientSecret);
var tokenRequestContext = new TokenRequestContext(scopes);
var token = clientSecretCredential.GetTokenAsync(tokenRequestContext).Result.Token;

//using http sender with the token
httpClient = new HttpClient();
httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token );
// Call the web API.
HttpResponseMessage response = await _httpClient.GetAsync(apiUri);
...
}