使用FCM服务

1.建谷歌账号

2.在console上新建应用 https://console.firebase.google.com 并下载私钥.json

3.创建测试网页应用 （或app应用）

C#服务端：

用HTTP v1 API 的方式获取OAuth2的验证，然后再发http请求到FCM发送消息通知。

1.获取Token

 public async Task<string> GetTokenAsync(string filePath)
         {
             var token = _redisDBManager.GetValue(filePath);
             if (token != null)
                 return token;

             try
             {
                 GoogleCredential credential = null;
                 using (var stream = new FileStream(filePath, FileMode.Open, FileAccess.Read))
                 {
                     credential = GoogleCredential.FromStream(stream)
                         .CreateScoped(@"https://www.googleapis.com/auth/firebase.messaging");
                 }
                 var result = await credential.UnderlyingCredential.GetAccessTokenForRequestAsync().ConfigureAwait(false);

                 _redisDBManager.SetValue(filePath, result, TimeSpan.FromMinutes());

                 return result;
             }
             catch (Exception e)
             {
                 Logger.LogError($"FCMManager getTokenAsync error, filePath = {filePath}", e);
                 return null;
             }
         }

2.从json解析ProjectId

 private static string GetProjectId(string serviceAccountKeyFile)
         {
             var serviceAccountKeyJson = File.ReadAllText(serviceAccountKeyFile);
             var serviceAccountKeyDictionary = JsonConvert.DeserializeObject<Dictionary<string, string>>(serviceAccountKeyJson);

             if (!serviceAccountKeyDictionary.ContainsKey("project_id"))
             {
                 throw new Exception($"Could not read Project ID from ServiceAccountKey File '{serviceAccountKeyFile}'");
             }

             return serviceAccountKeyDictionary["project_id"];
         }

3.发送消息

 public async Task<AcceptorNoticeInfo> SendAsync(FcmMessage message, string filePath)
         {
             try
             {
                 var token = await GetTokenAsync(filePath).ConfigureAwait(false);
                 if (token == null)
                 {
                     _redisDBManager.Remove(filePath);
                     token = await GetTokenAsync(filePath).ConfigureAwait(false);
                 }

                 var httpClient = new HttpClient();
                 httpClient.DefaultRequestHeaders
                     .Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
                 httpClient.DefaultRequestHeaders.TryAddWithoutValidation("Authorization", $"Bearer {token}");

                 StringContent content = new StringContent(JsonConvert.SerializeObject(message, new JsonSerializerSettings()
                 {
                     NullValueHandling = NullValueHandling.Ignore
                 }));
                 var projectId = GetProjectId(filePath);
                 var url = $"https://fcm.googleapis.com/v1/projects/{projectId}/messages:send";

                 var responseMessage = await httpClient.PostAsync(url, content)
                     .ConfigureAwait(false);

                 if (responseMessage.StatusCode == HttpStatusCode.OK)
                 {                     return new AcceptorNoticeInfo()
                     {
                         ErrorCode = (int)NoticeError.Success,
                         ErrorMessage = NoticeError.Success.ToString()
                     };
                 }
                 else
                 {
                     var responseContent = await responseMessage.Content.ReadAsStringAsync().ConfigureAwait(false);
                     var error = JsonConvert.DeserializeObject<FcmMessageErrorResponse>(responseContent);
                     return new AcceptorNoticeInfo()
                     {
                         ErrorCode = (int)responseMessage.StatusCode,
                         ErrorMessage = error.Error["message"].ToString()
                     };
                 }
             }
             catch (Exception ex)
             {
                 Logger.LogError($"FCM SendAsync error. token = {message.Message.Token}, topic = {message.Message.Token}{message.Message.Condition}", ex);
                 return new AcceptorNoticeInfo()
                 {
                     ErrorCode = (int)NoticeError.Failed,
                     ErrorMessage = NoticeError.Failed.ToString()
                 };
             }

         }