訊息類型
根據預設,訂閱項目會尋找所有與 應用程式的 Google Cloud 控制台專案頁面。這個 包括:
- 同一應用程式在其他裝置上發布的訊息。
- 該專案擁有的訊息,並附加至信標。詳情請見 在信標新增附件。
您的應用程式可以使用 MessageFilter
訂閱以接收更多類型的鄰近訊息,包括公共信標
及原始藍牙低功耗 (BLE) 信標 ID。
公開信標附件
開發人員可以將信標附件命名空間標示為 PUBLIC
。這樣一來,
擷取及擷取所有資料。適用對象
如要瞭解如何公開附件命名空間,請參閱
附件瀏覽權限。
範例:
// Subscribe for two different public beacon attachment types.
MessageFilter messageFilter = new MessageFilter.Builder()
.includeNamespacedType(EXAMPLE_PUBLIC_NAMESPACE_A, EXAMPLE_PUBLIC_TYPE_A)
.includeNamespacedType(EXAMPLE_PUBLIC_NAMESPACE_B, EXAMPLE_PUBLIC_TYPE_B)
.build();
SubscribeOptions options = new SubscribeOptions.Builder()
.setStrategy(Strategy.BLE_ONLY)
.setFilter(messageFilter)
.build();
MessageListener messageListener = new MessageListener() {
@Override
public void onFound(final Message message) {
// We may want to handle the two types of message differently.
if (EXAMPLE_PUBLIC_NAMESPACE_A.equals(message.getNamespace())
&& EXAMPLE_PUBLIC_TYPE_A.equals(message.getType())) {
// Handle a "type A" message.
} else if (EXAMPLE_PUBLIC_NAMESPACE_B.equals(message.getNamespace())
&& EXAMPLE_PUBLIC_TYPE_B.equals(message.getType())) {
// Handle a "type B" message.
}
}
};
Nearby.getMessagesClient(this).subscribe(messageListener, options);
BLE 信標 ID
您可以使用 Google 信標平台,將任何雲端資料 才能取得您的信標,去除 BLE 中所宣傳的實際信標 ID 資源數量根據預設,系統會尋找這些附件 (請參閱 訊息類型)。
不過,如果需要找出原始信標 ID (以便使用自己的信標 ID), 例如登錄檔目前有兩種支援的格式:
- Eddystone UID。
- 你可以使用
MessageFilter.Builder#includeEddystoneUids
找出這類資訊。
- 你可以使用
- iBeacon ID。
- 你可以使用
MessageFilter.Builder#includeIBeaconIds
找出這類資訊。
- 你可以使用
範例:
// Subscribe for all Eddystone UIDs whose first 10 bytes (the "namespace")
// match MY_EDDYSTONE_UID_NAMESPACE.
//
// Note that the Eddystone UID namespace is separate from the namespace
// field of a Nearby Message.
MessageFilter messageFilter = new MessageFilter.Builder()
.includeEddystoneUids(MY_EDDYSTONE_UID_NAMESPACE, null /* any instance */)
.build();
SubscribeOptions options = new SubscribeOptions.Builder()
.setStrategy(Strategy.BLE_ONLY)
.setFilter(messageFilter)
.build();
MessageListener messageListener = new MessageListener() {
@Override
public void onFound(final Message message) {
// Note: Checking the type shown for completeness, but is unnecessary
// if your message filter only includes a single type.
if (Message.MESSAGE_NAMESPACE_RESERVED.equals(message.getNamespace())
&& Message.MESSAGE_TYPE_EDDYSTONE_UID.equals(message.getType())) {
// Nearby provides the EddystoneUid class to parse Eddystone UIDs
// that have been found nearby.
EddystoneUid eddystoneUid = EddystoneUid.from(message);
Log.i(TAG, "Found Eddystone UID: " + eddystoneUid);
}
}
};
Nearby.getMessagesClient(this).subscribe(messageListener, options);
RSSI 和距離回呼
除了找到及遺失回呼外,前景訂閱項目可更新 MessageListener 。
- 這些額外的回呼目前只會針對 BLE 信標訊息傳送 (包括附件和信標 ID)。
- 這些額外的回呼不會傳送至背景 (
PendingIntent
) 訂閱項目。
範例:
MessageListener messageListener = new MessageListener() {
/**
* Called when a message is discovered nearby.
*/
@Override
public void onFound(final Message message) {
Log.i(TAG, "Found message: " + message);
}
/**
* Called when the Bluetooth Low Energy (BLE) signal associated with a message changes.
*
* This is currently only called for BLE beacon messages.
*
* For example, this is called when we see the first BLE advertisement
* frame associated with a message; or when we see subsequent frames with
* significantly different received signal strength indicator (RSSI)
* readings.
*
* For more information, see the MessageListener Javadocs.
*/
@Override
public void onBleSignalChanged(final Message message, final BleSignal bleSignal) {
Log.i(TAG, "Message: " + message + " has new BLE signal information: " + bleSignal);
}
/**
* Called when Nearby's estimate of the distance to a message changes.
*
* This is currently only called for BLE beacon messages.
*
* For more information, see the MessageListener Javadocs.
*/
@Override
public void onDistanceChanged(final Message message, final Distance distance) {
Log.i(TAG, "Distance changed, message: " + message + ", new distance: " + distance);
}
/**
* Called when a message is no longer detectable nearby.
*/
@Override
public void onLost(final Message message) {
Log.i(TAG, "Lost message: " + message);
}
};