Android 上的主題訊息

FCM 主題訊息功能採用發布/訂閱模式，可讓您向已選擇訂閱特定主題的多部裝置傳送訊息。您可以視需要撰寫主題訊息，FCM 會負責處理路由，並將訊息可靠地傳送至正確的裝置。

舉例來說，當地潮汐預測應用程式的使用者可以選擇訂閱「潮流警報」主題，接收特定區域最佳鹽水釣魚條件的通知。運動應用程式的使用者可以訂閱喜愛球隊的即時比數自動更新功能。

關於主題，請注意以下幾點：

  • 主題訊息最適合用於天氣或其他公開資訊等內容。
  • 主題訊息是針對總處理量而非延遲進行最佳化。如要快速安全地傳送至單一裝置或小型裝置群組，請 將訊息指定給註冊權杖，而非主題。
  • 如果您需要向每位使用者的多台裝置傳送訊息，請考慮針對這些用途使用 裝置群組訊息傳送。
  • 主題訊息支援每個主題的無限訂閱項目。不過，FCM 會在下列領域實施限制：
    • 一個應用程式執行個體最多只能訂閱 2,000 個主題。
    • 如果您使用批次匯入功能來訂閱應用程式執行個體，每個要求最多只能包含 1, 000 個應用程式執行個體。
    • 每個專案的新訂閱頻率都有頻率限制。如果您在短時間內傳送太多訂閱要求，FCM 伺服器會傳回 429 RESOURCE_EXHAUSTED (「配額超出」) 回應。以指數輪詢方式重試。

讓用戶端應用程式訂閱主題

用戶端應用程式可以訂閱任何現有主題，也可以建立新主題。當用戶端應用程式訂閱新主題名稱 (在您的 Firebase 專案中不存在) 時，系統會在 FCM 中建立該名稱的新主題，之後任何用戶端都可以訂閱該主題。

如要訂閱主題，用戶端應用程式會使用 FCM 主題名稱呼叫 Firebase Cloud Messaging subscribeToTopic()。這個方法會傳回 Task，可供完成事件監聽器用來判斷訂閱是否成功：

Kotlin+KTX

Firebase.messaging.subscribeToTopic("weather")
    .addOnCompleteListener { task ->
        var msg = "Subscribed"
        if (!task.isSuccessful) {
            msg = "Subscribe failed"
        }
        Log.d(TAG, msg)
        Toast.makeText(baseContext, msg, Toast.LENGTH_SHORT).show()
    }
MainActivity.kt

Java

FirebaseMessaging.getInstance().subscribeToTopic("weather")
        .addOnCompleteListener(new OnCompleteListener<Void>() {
            @Override
            public void onComplete(@NonNull Task<Void> task) {
                String msg = "Subscribed";
                if (!task.isSuccessful()) {
                    msg = "Subscribe failed";
                }
                Log.d(TAG, msg);
                Toast.makeText(MainActivity.this, msg, Toast.LENGTH_SHORT).show();
            }
        });
MainActivity.java

如要取消訂閱，用戶端應用程式會呼叫 Firebase Cloud Messaging unsubscribeFromTopic()，並傳入主題名稱。

在伺服器上管理主題訂閱

Firebase Admin SDK 可讓您從伺服器端執行基本主題管理工作。只要提供註冊權杖，您就能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。

您可以讓用戶端應用程式執行個體訂閱任何現有主題，也可以建立新主題。當您使用 API 將用戶端應用程式訂閱至新主題 (您的 Firebase 專案中不存在的) 時，系統會在 FCM 中建立同名的新主題，之後任何用戶端都可以訂閱該主題。

您可以將註冊權杖清單傳遞至 Firebase Admin SDK 訂閱方法，讓對應裝置訂閱主題：

Node.js

// These registration tokens come from the client FCM SDKs.
const registrationTokens = [
  'YOUR_REGISTRATION_TOKEN_1',
  // ...
  'YOUR_REGISTRATION_TOKEN_n'
];

// 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");
FirebaseMessagingSnippets.cs

管理員 FCM API 還可讓您將裝置從主題取消訂閱，方法是將註冊權杖傳遞至適當的方法：

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");
FirebaseMessagingSnippets.cs

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符記號數量為何，傳回類型都會採用相同的格式。

如果發生錯誤 (驗證失敗、權杖或主題無效等)，這些方法會導致錯誤。如需錯誤代碼的完整清單 (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 會以與其他下游訊息相同的方式傳送主題訊息。

如要接收訊息，請使用擴充 FirebaseMessagingService 的服務。您的服務應覆寫 onMessageReceived 和 onDeletedMessages 回呼。

處理訊息的時間視窗可能會短於 20 秒，這取決於呼叫 onMessageReceived 前發生的延遲時間，包括作業系統延遲、應用程式啟動時間、主執行緒遭其他作業阻斷，或先前 onMessageReceived 呼叫耗費過多時間。超過這段時間後，各種 OS 行為 (例如 Android 的程序終止或 Android O 的 背景執行限制) 可能會影響您完成工作的可能性。

onMessageReceived 適用於大多數郵件類型，但以下類型除外：

  • 在應用程式於背景運作期間傳送通知訊息。在這種情況下，系統會將通知傳送至裝置的系統匣。使用者輕觸通知後，系統預設會開啟應用程式啟動器。

  • 在背景接收的訊息，其中包含通知和資料酬載。在這種情況下，系統會將通知傳送至裝置的系統通知格，並在啟動器活動的意圖額外項目中傳送資料酬載。

簡單來說：

應用程式狀態 通知 資料 兩者並用
前景 onMessageReceived onMessageReceived onMessageReceived
背景 系統匣 onMessageReceived 通知：系統通知區
資料：意圖的額外資料。
如要進一步瞭解訊息類型，請參閱「通知和資料訊息」。

編輯應用程式資訊清單

如要使用 FirebaseMessagingService，您必須在應用程式資訊清單中新增下列內容：

<service
    android:name=".java.MyFirebaseMessagingService"
    android:exported="false">
    <intent-filter>
        <action android:name="com.google.firebase.MESSAGING_EVENT" />
    </intent-filter>
</service>
AndroidManifest.xml

此外，建議您設定預設值，自訂通知的外觀。您可以指定自訂預設圖示和自訂預設顏色，在通知酬載中未設定等值時套用。

在 application 標記中新增以下行，設定自訂預設圖示和自訂顏色：

<!-- Set custom default icon. This is used when no icon is set for incoming notification messages.
     See README(https://goo.gl/l4GJaQ) for more. -->
<meta-data
    android:name="com.google.firebase.messaging.default_notification_icon"
    android:resource="@drawable/ic_stat_ic_notification" />
<!-- Set color used with incoming notification messages. This is used when no color is set for the incoming
     notification message. See README(https://goo.gl/6BKBk7) for more. -->
<meta-data
    android:name="com.google.firebase.messaging.default_notification_color"
    android:resource="@color/colorAccent" />
AndroidManifest.xml

Android 會顯示自訂預設圖示

  • 所有透過 通知編輯器傳送的通知訊息。
  • 任何未在通知酬載中明確設定圖示的通知訊息。

Android 會使用自訂預設顏色

  • 所有透過 通知編輯器傳送的通知訊息。
  • 任何未在通知酬載中明確設定顏色的通知訊息。

如果未設定自訂的預設圖示，且通知酬載中也未設定圖示，Android 會顯示以白色顯示的應用程式圖示。

覆寫 onMessageReceived

您可以覆寫 FirebaseMessagingService.onMessageReceived 方法，根據收到的 RemoteMessage 物件執行動作，並取得訊息資料：

Kotlin+KTX

override fun onMessageReceived(remoteMessage: RemoteMessage) {
    // TODO(developer): Handle FCM messages here.
    // Not getting messages here? See why this may be: https://goo.gl/39bRNJ
    Log.d(TAG, "From: ${remoteMessage.from}")

    // Check if message contains a data payload.
    if (remoteMessage.data.isNotEmpty()) {
        Log.d(TAG, "Message data payload: ${remoteMessage.data}")

        // Check if data needs to be processed by long running job
        if (needsToBeScheduled()) {
            // For long-running tasks (10 seconds or more) use WorkManager.
            scheduleJob()
        } else {
            // Handle message within 10 seconds
            handleNow()
        }
    }

    // Check if message contains a notification payload.
    remoteMessage.notification?.let {
        Log.d(TAG, "Message Notification Body: ${it.body}")
    }

    // Also if you intend on generating your own notifications as a result of a received FCM
    // message, here is where that should be initiated. See sendNotification method below.
}
MyFirebaseMessagingService.kt

Java

@Override
public void onMessageReceived(RemoteMessage remoteMessage) {
    // TODO(developer): Handle FCM messages here.
    // Not getting messages here? See why this may be: https://goo.gl/39bRNJ
    Log.d(TAG, "From: " + remoteMessage.getFrom());

    // Check if message contains a data payload.
    if (remoteMessage.getData().size() > 0) {
        Log.d(TAG, "Message data payload: " + remoteMessage.getData());

        if (/* Check if data needs to be processed by long running job */ true) {
            // For long-running tasks (10 seconds or more) use WorkManager.
            scheduleJob();
        } else {
            // Handle message within 10 seconds
            handleNow();
        }

    }

    // Check if message contains a notification payload.
    if (remoteMessage.getNotification() != null) {
        Log.d(TAG, "Message Notification Body: " + remoteMessage.getNotification().getBody());
    }

    // Also if you intend on generating your own notifications as a result of a received FCM
    // message, here is where that should be initiated. See sendNotification method below.
}
MyFirebaseMessagingService.java

覆寫 onDeletedMessages

在某些情況下，FCM 可能無法傳送訊息。發生這種情況的原因是，在特定裝置連線時，應用程式有太多 (超過 100 則) 待處理訊息，或是裝置在一個多月內未連線至 FCM。在這些情況下，您可能會收到 FirebaseMessagingService.onDeletedMessages() 的回呼。當應用程式執行個體收到這項回呼時，應會與應用程式伺服器執行完整同步處理。如果您在過去 4 週內未向該裝置上的應用程式傳送訊息，FCM 就不會呼叫 onDeletedMessages()。

在背景應用程式中處理通知訊息

當應用程式處於背景執行時，Android 會將通知訊息導向系統匣。使用者輕觸通知後，系統會根據預設開啟應用程式啟動器。

這包括同時包含通知和資料酬載的訊息 (以及透過「通知」資訊主頁傳送的所有訊息)。在這些情況下，系統會將通知傳送至裝置的系統通知區，並在啟動器活動的意圖額外項目中傳送資料酬載。

如要深入瞭解應用程式訊息的傳送情形，請參閱 FCM 報表資訊主頁，這可記錄在 Apple 和 Android 裝置上傳送及開啟的訊息數量，以及 Android 應用程式「曝光次數」(使用者看到的通知) 資料。

建立傳送要求

建立主題後，您可以透過訂閱用戶端應用程式執行個體，或透過伺服器 API，將訊息傳送至主題。如果這是您首次為 FCM 建立傳送要求，請參閱指南，瞭解伺服器環境和 FCM 的重要背景和設定資訊。

在後端的傳送邏輯中，指定所需的專案名稱，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);
FirebaseMessagingSnippets.java

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)
cloud_messaging.py

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)
messaging.go

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

如要將訊息傳送至主題組合，請指定條件，這是指定目標主題的布林運算式。舉例來說，下列條件會將訊息傳送至已訂閱 TopicA 和 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，然後從左到右評估運算式。在上述運算式中，訂閱任何單一主題的使用者都不會收到訊息。同樣地，未訂閱 TopicA 的使用者也不會收到這則訊息。以下組合會收到這項通知：

  • TopicA 和 TopicB
  • TopicA 和 TopicC

您最多可以在條件式運算式中加入五個主題。

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);
FirebaseMessagingSnippets.java

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)
cloud_messaging.py

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)
messaging.go

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

後續步驟