根據發布/訂閱模型，FCM 主題訊息功能可讓您將訊息傳送至已選擇加入特定主題的多部裝置。您可根據需要編寫主題訊息，而 FCM 會妥善處理訊息轉送作業，並將訊息安全傳送至正確的裝置。
舉例來說，當地潮汐預測應用程式的使用者可選擇「潮時報」主題，並在特定地區收到最佳海水釣魚情況的通知。運動應用程式的使用者可以訂閱喜愛球隊的即時賽事比分自動更新。
使用主題時，請注意下列事項：
- 主題訊息最適合用於天氣或其他公開資訊等內容。
- 主題訊息針對處理量進行最佳化，而非延遲時間。如要以快速又安全的方式將訊息傳送至單一裝置或少數裝置，建議您 將訊息傳送至註冊權杖，而非主題。
- 如果您需要向「每位使用者」傳送訊息給多部裝置，請考慮因應這些用途的 裝置群組訊息。
- 每個主題的訊息功能支援無限次訂閱。然而，FCM 會在以下方面強制執行限制：
- 每個應用程式執行個體最多只能訂閱 2000 個主題。
- 如果您使用批次匯入功能訂閱應用程式執行個體，則每項要求最多只能包含 1000 個應用程式執行個體。
- 每項專案的新增訂閱頻率都設有頻率限制。如果您在短時間內傳送過多訂閱要求，FCM 伺服器會傳回
429 RESOURCE_EXHAUSTED(「超出配額」) 回應。以指數輪詢方式重試。
為用戶端應用程式訂閱主題
如要訂閱主題，請從應用程式呼叫 Firebase.Messaging.FirebaseMessaging.Subscribe。這會向 FCM 後端發出非同步要求，並訂閱用戶端指定的主題。
Firebase.Messaging.FirebaseMessaging.Subscribe("/topics/example");
如果訂閱要求一開始失敗，FCM 會重試，直到成功訂閱主題為止。每次應用程式啟動時，FCM 會確保已訂閱所有要求的主題。
如要取消訂閱，請呼叫 Firebase.Messaging.FirebaseMessaging.Unsubscribe，FCM 會在背景取消訂閱該主題。
管理伺服器上的主題訂閱
Firebase Admin SDK 可讓您從伺服器端執行基本主題管理工作。基於註冊權杖的註冊權杖，您可以使用伺服器邏輯大量訂閱及取消訂閱用戶端應用程式執行個體。
您可以訂閱用戶端應用程式執行個體到任何現有主題，或是建立新主題。當您使用 API 訂閱用戶端應用程式的新主題 (您的 Firebase 專案尚未使用的主題) 時，系統會在 FCM 中建立名為該名稱的新主題，任何用戶端隨後都能訂閱該主題。
您可以將註冊權杖清單傳遞至 Firebase Admin SDK 訂閱方法，藉此訂閱對應的裝置：
Node.js
// These registration tokens come from the client FCM SDKs.
const registrationTokens = [
'YOUR_REGISTRATION_TOKEN_1',
// ...
'YOUR_REGISTRATION_TOKEN_n'
];
// Subscribe the devices corresponding to the registration tokens to the
// topic.
getMessaging().subscribeToTopic(registrationTokens, topic)
.then((response) => {
// See the MessagingTopicManagementResponse reference documentation
// for the contents of response.
console.log('Successfully subscribed to topic:', response);
})
.catch((error) => {
console.log('Error subscribing to topic:', error);
});
Java
// These registration tokens come from the client FCM SDKs.
List<String> registrationTokens = Arrays.asList(
"YOUR_REGISTRATION_TOKEN_1",
// ...
"YOUR_REGISTRATION_TOKEN_n"
);
// Subscribe the devices corresponding to the registration tokens to the
// topic.
TopicManagementResponse response = FirebaseMessaging.getInstance().subscribeToTopic(
registrationTokens, topic);
// See the TopicManagementResponse reference documentation
// for the contents of response.
System.out.println(response.getSuccessCount() + " tokens were subscribed successfully");
Python
# These registration tokens come from the client FCM SDKs.
registration_tokens = [
'YOUR_REGISTRATION_TOKEN_1',
# ...
'YOUR_REGISTRATION_TOKEN_n',
]
# Subscribe the devices corresponding to the registration tokens to the
# topic.
response = messaging.subscribe_to_topic(registration_tokens, topic)
# See the TopicManagementResponse reference documentation
# for the contents of response.
print(response.success_count, 'tokens were subscribed successfully')
Go
// These registration tokens come from the client FCM SDKs.
registrationTokens := []string{
"YOUR_REGISTRATION_TOKEN_1",
// ...
"YOUR_REGISTRATION_TOKEN_n",
}
// Subscribe the devices corresponding to the registration tokens to the
// topic.
response, err := client.SubscribeToTopic(ctx, registrationTokens, topic)
if err != nil {
log.Fatalln(err)
}
// See the TopicManagementResponse reference documentation
// for the contents of response.
fmt.Println(response.SuccessCount, "tokens were subscribed successfully")
C#
// These registration tokens come from the client FCM SDKs.
var registrationTokens = new List<string>()
{
"YOUR_REGISTRATION_TOKEN_1",
// ...
"YOUR_REGISTRATION_TOKEN_n",
};
// Subscribe the devices corresponding to the registration tokens to the
// topic
var response = await FirebaseMessaging.DefaultInstance.SubscribeToTopicAsync(
registrationTokens, topic);
// See the TopicManagementResponse reference documentation
// for the contents of response.
Console.WriteLine($"{response.SuccessCount} tokens were subscribed successfully");
Admin FCM API 也可讓您將註冊權杖傳遞至適當的方法，藉此為裝置取消訂閱主題：
Node.js
// These registration tokens come from the client FCM SDKs.
const registrationTokens = [
'YOUR_REGISTRATION_TOKEN_1',
// ...
'YOUR_REGISTRATION_TOKEN_n'
];
// Unsubscribe the devices corresponding to the registration tokens from
// the topic.
getMessaging().unsubscribeFromTopic(registrationTokens, topic)
.then((response) => {
// See the MessagingTopicManagementResponse reference documentation
// for the contents of response.
console.log('Successfully unsubscribed from topic:', response);
})
.catch((error) => {
console.log('Error unsubscribing from topic:', error);
});
Java
// These registration tokens come from the client FCM SDKs.
List<String> registrationTokens = Arrays.asList(
"YOUR_REGISTRATION_TOKEN_1",
// ...
"YOUR_REGISTRATION_TOKEN_n"
);
// Unsubscribe the devices corresponding to the registration tokens from
// the topic.
TopicManagementResponse response = FirebaseMessaging.getInstance().unsubscribeFromTopic(
registrationTokens, topic);
// See the TopicManagementResponse reference documentation
// for the contents of response.
System.out.println(response.getSuccessCount() + " tokens were unsubscribed successfully");
Python
# These registration tokens come from the client FCM SDKs.
registration_tokens = [
'YOUR_REGISTRATION_TOKEN_1',
# ...
'YOUR_REGISTRATION_TOKEN_n',
]
# Unubscribe the devices corresponding to the registration tokens from the
# topic.
response = messaging.unsubscribe_from_topic(registration_tokens, topic)
# See the TopicManagementResponse reference documentation
# for the contents of response.
print(response.success_count, 'tokens were unsubscribed successfully')
Go
// These registration tokens come from the client FCM SDKs.
registrationTokens := []string{
"YOUR_REGISTRATION_TOKEN_1",
// ...
"YOUR_REGISTRATION_TOKEN_n",
}
// Unsubscribe the devices corresponding to the registration tokens from
// the topic.
response, err := client.UnsubscribeFromTopic(ctx, registrationTokens, topic)
if err != nil {
log.Fatalln(err)
}
// See the TopicManagementResponse reference documentation
// for the contents of response.
fmt.Println(response.SuccessCount, "tokens were unsubscribed successfully")
C#
// These registration tokens come from the client FCM SDKs.
var registrationTokens = new List<string>()
{
"YOUR_REGISTRATION_TOKEN_1",
// ...
"YOUR_REGISTRATION_TOKEN_n",
};
// Unsubscribe the devices corresponding to the registration tokens from the
// topic
var response = await FirebaseMessaging.DefaultInstance.UnsubscribeFromTopicAsync(
registrationTokens, topic);
// See the TopicManagementResponse reference documentation
// for the contents of response.
Console.WriteLine($"{response.SuccessCount} tokens were unsubscribed successfully");
subscribeToTopic() 和 unsubscribeFromTopic() 方法會產生物件，其中包含 FCM 的回應。無論要求中指定的註冊權杖數量為何，傳回類型的格式都相同。
如果發生錯誤 (驗證失敗、憑證無效或主題等)，這些方法就會發生錯誤。如需完整的錯誤代碼清單 (包括說明和解決步驟)，請參閱「Admin FCM API 錯誤」。
接收及處理主題訊息
FCM 傳送主題訊息的方式與其他下游訊息相同。
訂閱事件 Firebase.Messaging.FirebaseMessaging.MessageReceived 事件，即可根據收到的訊息執行動作並取得訊息資料。
Firebase.Messaging.FirebaseMessaging.MessageReceived += OnMessageReceived;
...
public void OnMessageReceived(object sender, Firebase.Messaging.MessageReceivedEventArgs e) {
UnityEngine.Debug.Log("Received a new message");
if (e.Message.From.Length > 0)
UnityEngine.Debug.Log("from: " + e.Message.From);
if (e.Message.Data.Count > 0) {
UnityEngine.Debug.Log("data:");
foreach (System.Collections.Generic.KeyValuePair iter in
e.Message.Data) {
UnityEngine.Debug.Log(" " + iter.Key + ": " + iter.Value);
}
}
}
版本傳送要求
建立主題後，透過在用戶端訂閱用戶端應用程式執行個體或透過伺服器 API，即可將訊息傳送至主題。如果這是您第一次建構 FCM 的要求，請參閱伺服器環境和 FCM 指南，瞭解重要背景和設定資訊。
在後端的傳送邏輯中，指定所需的主題名稱，如下所示：
Node.js
// The topic name can be optionally prefixed with "/topics/".
const topic = 'highScores';
const message = {
data: {
score: '850',
time: '2:45'
},
topic: topic
};
// Send a message to devices subscribed to the provided topic.
getMessaging().send(message)
.then((response) => {
// Response is a message ID string.
console.log('Successfully sent message:', response);
})
.catch((error) => {
console.log('Error sending message:', error);
});
Java
// The topic name can be optionally prefixed with "/topics/".
String topic = "highScores";
// See documentation on defining a message payload.
Message message = Message.builder()
.putData("score", "850")
.putData("time", "2:45")
.setTopic(topic)
.build();
// Send a message to the devices subscribed to the provided topic.
String response = FirebaseMessaging.getInstance().send(message);
// Response is a message ID string.
System.out.println("Successfully sent message: " + response);
Python
# The topic name can be optionally prefixed with "/topics/".
topic = 'highScores'
# See documentation on defining a message payload.
message = messaging.Message(
data={
'score': '850',
'time': '2:45',
},
topic=topic,
)
# Send a message to the devices subscribed to the provided topic.
response = messaging.send(message)
# Response is a message ID string.
print('Successfully sent message:', response)
Go
// The topic name can be optionally prefixed with "/topics/".
topic := "highScores"
// See documentation on defining a message payload.
message := &messaging.Message{
Data: map[string]string{
"score": "850",
"time": "2:45",
},
Topic: topic,
}
// Send a message to the devices subscribed to the provided topic.
response, err := client.Send(ctx, message)
if err != nil {
log.Fatalln(err)
}
// Response is a message ID string.
fmt.Println("Successfully sent message:", response)
C#
// The topic name can be optionally prefixed with "/topics/".
var topic = "highScores";
// See documentation on defining a message payload.
var message = new Message()
{
Data = new Dictionary<string, string>()
{
{ "score", "850" },
{ "time", "2:45" },
},
Topic = topic,
};
// Send a message to the devices subscribed to the provided topic.
string response = await FirebaseMessaging.DefaultInstance.SendAsync(message);
// Response is a message ID string.
Console.WriteLine("Successfully sent message: " + response);
REST
POST https://fcm.googleapis.com/v1/projects/myproject-b5ae1/messages:send HTTP/1.1
Content-Type: application/json
Authorization: Bearer ya29.ElqKBGN2Ri_Uz...HnS_uNreA
{
"message":{
"topic" : "foo-bar",
"notification" : {
"body" : "This is a Firebase Cloud Messaging Topic Message!",
"title" : "FCM Message"
}
}
}
cURL 指令：
curl -X POST -H "Authorization: Bearer ya29.ElqKBGN2Ri_Uz...HnS_uNreA" -H "Content-Type: application/json" -d '{
"message": {
"topic" : "foo-bar",
"notification": {
"body": "This is a Firebase Cloud Messaging Topic Message!",
"title": "FCM Message"
}
}
}' https://fcm.googleapis.com/v1/projects/myproject-b5ae1/messages:send HTTP/1.1
如要傳送訊息至主題的「組合」，請指定「條件」，這是指定了目標主題的布林值運算式。舉例來說，下列條件會將訊息傳送至訂閱 TopicA 以及 TopicB 或 TopicC 的裝置：
"'TopicA' in topics && ('TopicB' in topics || 'TopicC' in topics)"
FCM 會先評估括號中的任何條件，然後由左至右評估運算式。在上述運算式中，訂閱任何單一主題的使用者不會收到訊息。同樣地，未訂閱 TopicA 的使用者也不會收到訊息。這些組合可以接收：
TopicA和TopicBTopicA和TopicC
條件運算式最多可加入五個主題。
如要傳送至條件：
Node.js
// Define a condition which will send to devices which are subscribed
// to either the Google stock or the tech industry topics.
const condition = '\'stock-GOOG\' in topics || \'industry-tech\' in topics';
// See documentation on defining a message payload.
const message = {
notification: {
title: '$FooCorp up 1.43% on the day',
body: '$FooCorp gained 11.80 points to close at 835.67, up 1.43% on the day.'
},
condition: condition
};
// Send a message to devices subscribed to the combination of topics
// specified by the provided condition.
getMessaging().send(message)
.then((response) => {
// Response is a message ID string.
console.log('Successfully sent message:', response);
})
.catch((error) => {
console.log('Error sending message:', error);
});
Java
// Define a condition which will send to devices which are subscribed
// to either the Google stock or the tech industry topics.
String condition = "'stock-GOOG' in topics || 'industry-tech' in topics";
// See documentation on defining a message payload.
Message message = Message.builder()
.setNotification(Notification.builder()
.setTitle("$GOOG up 1.43% on the day")
.setBody("$GOOG gained 11.80 points to close at 835.67, up 1.43% on the day.")
.build())
.setCondition(condition)
.build();
// Send a message to devices subscribed to the combination of topics
// specified by the provided condition.
String response = FirebaseMessaging.getInstance().send(message);
// Response is a message ID string.
System.out.println("Successfully sent message: " + response);
Python
# Define a condition which will send to devices which are subscribed
# to either the Google stock or the tech industry topics.
condition = "'stock-GOOG' in topics || 'industry-tech' in topics"
# See documentation on defining a message payload.
message = messaging.Message(
notification=messaging.Notification(
title='$GOOG up 1.43% on the day',
body='$GOOG gained 11.80 points to close at 835.67, up 1.43% on the day.',
),
condition=condition,
)
# Send a message to devices subscribed to the combination of topics
# specified by the provided condition.
response = messaging.send(message)
# Response is a message ID string.
print('Successfully sent message:', response)
Go
// Define a condition which will send to devices which are subscribed
// to either the Google stock or the tech industry topics.
condition := "'stock-GOOG' in topics || 'industry-tech' in topics"
// See documentation on defining a message payload.
message := &messaging.Message{
Data: map[string]string{
"score": "850",
"time": "2:45",
},
Condition: condition,
}
// Send a message to devices subscribed to the combination of topics
// specified by the provided condition.
response, err := client.Send(ctx, message)
if err != nil {
log.Fatalln(err)
}
// Response is a message ID string.
fmt.Println("Successfully sent message:", response)
C#
// Define a condition which will send to devices which are subscribed
// to either the Google stock or the tech industry topics.
var condition = "'stock-GOOG' in topics || 'industry-tech' in topics";
// See documentation on defining a message payload.
var message = new Message()
{
Notification = new Notification()
{
Title = "$GOOG up 1.43% on the day",
Body = "$GOOG gained 11.80 points to close at 835.67, up 1.43% on the day.",
},
Condition = condition,
};
// Send a message to devices subscribed to the combination of topics
// specified by the provided condition.
string response = await FirebaseMessaging.DefaultInstance.SendAsync(message);
// Response is a message ID string.
Console.WriteLine("Successfully sent message: " + response);
REST
POST https://fcm.googleapis.com/v1/projects/myproject-b5ae1/messages:send HTTP/1.1
Content-Type: application/json
Authorization: Bearer ya29.ElqKBGN2Ri_Uz...HnS_uNreA
{
"message":{
"condition": "'dogs' in topics || 'cats' in topics",
"notification" : {
"body" : "This is a Firebase Cloud Messaging Topic Message!",
"title" : "FCM Message",
}
}
}
cURL 指令：
curl -X POST -H "Authorization: Bearer ya29.ElqKBGN2Ri_Uz...HnS_uNreA" -H "Content-Type: application/json" -d '{
"notification": {
"title": "FCM Message",
"body": "This is a Firebase Cloud Messaging Topic Message!",
},
"condition": "'dogs' in topics || 'cats' in topics"
}' https://fcm.googleapis.com/v1/projects/myproject-b5ae1/messages:send HTTP/1.1