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(50));

                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)
                {31                     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()
                };
            }
            

        }