在我的Android应用中，我使用的是谷歌的移动后端入门。我希望在服务器上的CloudEntities更新时收到通知，并且此通知应包含来自更新的实体的一些数据。它在应用程序在后台运行时有效，但当我关闭应用程序时（通过在多任务处理视图中滑动它），我无法发出此类通知，因为我无法访问CloudBackendAsync在GCMIntentService。
我已经看到了这个问题： Mobile Backend handle continuous queries in background
但它没有解决在GCMIntentService中访问云数据的问题。
编辑：我在GCMIntentService.java中的当前代码
protected void onHandleIntent(Intent intent) {
//... (Check if the GCM Message is about an update of the Mobile Backend)
// dispatch message
if (GCM_TYPEID_QUERY.equals(typeId)) {
// Here, a broadcast is sent to the Main Activity of the app, which then downloads
// the new content and shows a notification in the CloudCallbackHandler. That
// only works when the Activity is running.
// So I would like to get access to the CloudBackendAsync instance from
// the app here to download data in the background and show a notification.
Intent messageIntent = new Intent(BROADCAST_ON_MESSAGE);
messageIntent.putExtras(intent);
messageIntent.putExtra("token", tokens[2]);
LocalBroadcastManager.getInstance(this).sendBroadcast(messageIntent);
}
//...
}
答案 0 :(得分：1)
Android客户端没有通过来自后端的推送通知事件接收消息内容（仅从演示后端发送subId令牌，这足以通知客户端已收到针对给定主题的一些新消息，刷新它。）
据我了解，除非我们更改后端代码，否则无法直接在客户端GCMIntentService.onHandleIntent（）方法中获取实体数据。我在后端类ProspectiveSearchServlet中进行了以下更改，以便它还包含推送通知中的消息内容：
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOException {
// Return if push notification is not enabled
if (!backendConfigManager.isPushEnabled()) {
log.info("ProspectiveSearchServlet: couldn't send push notification because it is disabled.");
return;
}
// dispatch GCM messages to each subscribers
String[] subIds = req.getParameterValues("id");
// Each subId has this format "<regId>:query:<clientSubId>"
for (String subId : subIds) {
String regId = SubscriptionUtility.extractRegId(subId);
if (isSubscriptionActive(regId)) {
Entity matchedEntity = ProspectiveSearchServiceFactory.getProspectiveSearchService().getDocument(req);
if(matchedEntity != null) {
log.info(String.format("ProspectiveSearchServlet: matchedEntity.toString: " + matchedEntity.toString()));
} else {
log.info(String.format("ProspectiveSearchServlet: matchedEntity is null."));
}
//Add the matchedEntity object.
sendPushNotification(regId, subId, matchedEntity);
} else {
SubscriptionUtility.clearSubscriptionAndDeviceEntity(Arrays.asList(regId));
}
}
}
private void sendPushNotification(String regId, String subId, Entity matchedEntity) throws IOException {
SubscriptionUtility.MobileType type = SubscriptionUtility.getMobileType(subId);
if (SubscriptionUtility.MobileType.ANDROID == type) {
sendGcmAlert(subId, regId, matchedEntity);
} else if (SubscriptionUtility.MobileType.IOS == type) {
sendIosAlert(subId, new String[] {regId}, matchedEntity);
}
}
private void sendGcmAlert(String subId, String regId, Entity matchedEntity)
throws IOException {
String gcmKey = backendConfigManager.getGcmKey();
boolean isGcmKeySet = !(gcmKey == null || gcmKey.trim().length() == 0);
// Only attempt to send GCM if GcmKey is available
if (isGcmKeySet) {
Sender sender = new Sender(gcmKey);
if(matchedEntity != null) {
Message message = new Message.Builder().addData(SubscriptionUtility.GCM_KEY_SUBID, subId)
//extra data.<key> elements can be added here
.addData("data.message", (String) matchedEntity.getProperty("message"))
.addData("data.updatedBy", (String) matchedEntity.getProperty("_updatedBy"))
.addData("data.owner", (String) matchedEntity.getProperty("_owner"))
.addData("data.kindName", (String) matchedEntity.getProperty("_kindName"))
.build();
Result r = sender.send(message, regId, GCM_SEND_RETRIES);
if (r.getMessageId() != null) {
log.info("ProspectiveSearchServlet: GCM sent: subId: " + subId);
} else {
log.warning("ProspectiveSearchServlet: GCM error for subId: " + subId +
", senderId: " + gcmKey + ", error: " + r.getErrorCodeName());
ArrayList<String> deviceIds = new ArrayList<String>();
deviceIds.add(regId);
SubscriptionUtility.clearSubscriptionAndDeviceEntity(deviceIds);
}
}
} else {
// Otherwise, just write a log entry
log.info(String.format("ProspectiveSearchServlet: GCM is not sent: GcmKey: %s ",
isGcmKeySet));
}
}
现在在客户端，您可以在GCMIntentService中进行以下更改，以显示正确的推送通知（使用消息正文和用户名）：
@Override
protected void onHandleIntent(Intent intent) {
Bundle extras = intent.getExtras();
GoogleCloudMessaging gcm = GoogleCloudMessaging.getInstance(this);
// The getMessageType() intent parameter must be the intent you received
// in your BroadcastReceiver.
String messageType = gcm.getMessageType(intent);
if (!extras.isEmpty()) { // has effect of unparcelling Bundle
/*
* Filter messages based on message type. Since it is likely that GCM will be
* extended in the future with new message types, just ignore any message types you're
* not interested in, or that you don't recognize.
*/
if (GoogleCloudMessaging.MESSAGE_TYPE_SEND_ERROR.equals(messageType)) {
Log.i(Consts.TAG, "onHandleIntent: message error");
} else if (GoogleCloudMessaging.MESSAGE_TYPE_DELETED.equals(messageType)) {
Log.i(Consts.TAG, "onHandleIntent: message deleted");
// If it's a regular GCM message, do some work.
} else if (GoogleCloudMessaging.MESSAGE_TYPE_MESSAGE.equals(messageType)) {
String subId = intent.getStringExtra(GCM_KEY_SUBID);
Log.i(Consts.TAG, "onHandleIntent: subId: " + subId);
String[] tokens = subId.split(":");
String typeId = tokens[1];
// dispatch message
if (GCM_TYPEID_QUERY.equals(typeId)) {
Intent messageIntent = new Intent(BROADCAST_ON_MESSAGE);
messageIntent.putExtras(intent);
messageIntent.putExtra("token", tokens[2]);
boolean isReceived = LocalBroadcastManager.getInstance(this).sendBroadcast(messageIntent);
//Check if the broadcast has been handled, if not show the notification.
if (!isReceived) {
Log.i(Consts.TAG, "A message has been recieved but no broadcast was handled.");
generateNotification(this, intent, tokens[2]);
} else {
Log.i(Consts.TAG, "A message has been recieved, broadcasted and handled.");
}
}
}
}
// Release the wake lock provided by the WakefulBroadcastReceiver.
GCMBroadcastReceiver.completeWakefulIntent(intent);
}
public static void generateNotification(Context context, Intent intent, String message) {
//Event keys
HashMap data = new HashMap();
for (String key : intent.getExtras().keySet()) {
Log.d(Consts.TAG, "Message key: " + key + " value: " + intent.getExtras().getString(key));
String eventKey = key.startsWith("data.") ? key.substring(5) : key;
data.put(eventKey, intent.getExtras().getString(key));
}
CharSequence contentTitle = (CharSequence) data.get("updatedBy");
if (contentTitle == null) contentTitle = "New Message";
CharSequence contentText = (CharSequence) data.get("message");
if (contentText == null) contentText = "";
CharSequence userId = (CharSequence) data.get("updatedBy");
Bitmap iconBitmap = getUserIcon(context, userId.toString());
if (iconBitmap == null) iconBitmap = BitmapFactory.decodeResource(context.getResources(), R.drawable.ic_launcher);
// Creates an Intent for the Activity
Intent resultIntent = new Intent(context, GuestbookActivity.class);
// The stack builder object will contain an artificial back stack for the started Activity.
// This ensures that navigating backward from the Activity leads out of
// your application to the Home screen.
TaskStackBuilder stackBuilder = TaskStackBuilder.create(context);
// Adds the back stack for the Intent (but not the Intent itself)
stackBuilder.addParentStack(IntroductionActivity.class);
// Adds the Intent that starts the Activity to the top of the stack
stackBuilder.addNextIntent(resultIntent);
PendingIntent resultPendingIntent = stackBuilder.getPendingIntent(0, PendingIntent.FLAG_UPDATE_CURRENT);
Notification.Builder mBuilder = new Notification.Builder(context);
mBuilder.setContentIntent(resultPendingIntent);
Notification notification = mBuilder
.setContentTitle(contentTitle)
.setContentText(contentText)
.setSmallIcon(R.drawable.notification_icon)
.setLargeIcon(iconBitmap)
.setTicker(contentTitle + ": " + contentText)
.setWhen(System.currentTimeMillis())
.setAutoCancel(true)
.build();
///Get the notification ID, /it allows to update the notification later on.
int notifyID = 1;
String contentID = (String) data.get("id");
if(contentID != null) {
notifyID = Integer.parseInt(contentID);
}
NotificationManager mNotificationManager = (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);
mNotificationManager.notify(notifyID, notification);
}