private static async Task<bool> CreateHttpHandlerUsingWindowsDefaultCredentialsAsync(){try{var response = await StoreCredentialsIfDomainControllerIsAccessibleAsync(CredentialCache.DefaultNetworkCredentials, false);if(!response.IsSuccessStatusCode){//server responds but windows credential cannot loginif(response.StatusCode==HttpStatusCode.Unauthorized){return false;}}return true;}catch(Exception e){if (e.InnerException is WebException webException){if (webException.Response is HttpWebResponse webResponse){if (webResponse.StatusCode == HttpStatusCode.Unauthorized)return false;}}throw;}}public static async Task<HttpResponseMessage> StoreCredentialsIfDomainControllerIsAccessibleAsync(NetworkCredential credentials, bool rememberCredentials){var uriForTestingConnection = $"{BaseAddress}<url for testing connection>";            var httpClient = new HttpClient(new HttpClientHandler { Credentials = credentials });var res = await httpClient.GetAsync(uriForTestingConnection);if (res.IsSuccessStatusCode){                HttpClientFactory hc = Instance;hc.Credentials = credentials;if (rememberCredentials)CredentialUtil.SetCredentials(BaseAddress, credentials.UserName, // store domain and username // in Credential.Usernamecredentials.Password, PersistanceType.Enterprise);elseCredentialUtil.RemoveCredentials(BaseAddress);}           return res;}

对webApi连接的测试是在StoreCredentialsIfDomainControllerIsAccessibleAsync方法中完成的，该方法将默认网络凭据添加到HttpClientHandler并调用Get方法。如果响应是Success代码，则使用CredentialUtil类存储凭据。这些WebApi调用被包装在Try Catch块中，以处理webApi可能关闭的情况，因此返回不成功的状态代码。

public static class CredentialUtil{public static string GetPasswordIfRemembered(string target){var cm = new Credential {Target=target };cm.Load();return cm.Password;}public static string GetUserNameIfRemembered(string target){var cm = new Credential { Target=target};cm.Load();return cm.Username;}public static bool SetCredentials(string target, string username, string password, PersistanceType persistenceType){return new Credential{Target = target,Username = username,Password = password,PersistanceType = persistenceType}.Save();}public static bool RemoveCredentials(string target){return new Credential { Target=target}.Delete();}}

如果使用默认的网络凭据登录失败，则会加载“登录对话框”。用户可以提供其凭据来访问该服务，该服务在经过验证后将加载主应用程序页面。在随附的示例中，使用MVVMLight框架完成Login视图的加载。