Question

我正在尝试使用实时消息应用程序（不像WhatsApp这样的聊天应用程序，我有一个发布者和许多订阅者）。

我希望它在收到新消息时发送通知。

这是我的代码（有错误）：

mRef.addChildEventListener(new ChildEventListener() {
        @Override
        public void onChildAdded(DataSnapshot dataSnapshot, String s) {
        for (DataSnapshot postSnapshot : dataSnapshot.getChildren()){
            Message message = postSnapshot.getValue(Message.class);
            messages.add(0, message.getTitle() + '\n' + message.getMessage(), NotificationCompat.Builder mBuilder = //cannot resolve symbol 'mBuilder'
                    new NotificationCompat.Builder(this) //builder (android.content.Context) in Builder cannot be applied to (anonymous com.firebase.client.ChildEventListener)
                            .setSmallIcon(R.drawable.logo_he_digita_homepage)
                            .setContentTitle(message.getTitle())
                            .setContentText(message.getMessage()); //')' expected
                    Intent resultIntent = new Intent(this, updates.class); //Cannot resolve constructor 'Intent(anonymous com.firebase.client.ChildEventListener, java.lang.Class<com.inbar.amit.ksharet>)'
                    TaskStackBuilder stackBuilder = TaskStackBuilder.create(this); //create (android.content.Context) in TaskStackBuilder cannot be applied to (anonymous com.firebase.client.ChildEventListener)
                    stackBuilder.addParentStack(updates.class);
                    stackBuilder.addNextIntent(resultIntent);
                    PendingIntent resultPendingIntent = 
                            stackBuilder.getPendingIntent(
                            0,
                            PendingIntent.FLAG_UPDATE_CURRENT
                    );
                    mBuilder.setContentIntent(resultPendingIntent);
                    NotificationManager mNotificationManager = 
                            (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
                    mNotificationManager.notify(124453245, mBuilder.build()););

        }
            adapter.notifyDataSetChanged();

        }

我正在使用Android Studio。

感谢您的回答。

Answer 1

首先，请注意，将为数据库中已有的每个子项调用onChildAdded，并在您开始侦听后添加每个子项，因此您最终会收到数据库中每条消息的通知。

<强>更新

因此，您需要为此代码创建一个新函数，因为它在侦听器类中不起作用。以下代码应该适合您：

mRef.addChildEventListener(new ChildEventListener() {
    @Override
    public void onChildAdded(DataSnapshot dataSnapshot, String s) {
    for (DataSnapshot postSnapshot : dataSnapshot.getChildren()){
        Message message = postSnapshot.getValue(Message.class);
        messages.add(0, message.getTitle() + '\n' + message.getMessage());
        sendNotification(message);

    }
        adapter.notifyDataSetChanged();

    }

在其他方法之外，添加此方法：

public void sendNotification(Message message) {
    NotificationCompat.Builder mBuilder =
        new NotificationCompat.Builder(this) 
            .setSmallIcon(R.drawable.logo_he_digita_homepage)
            .setContentTitle(message.getTitle())
            .setContentText(message.getMessage());
        Intent resultIntent = new Intent(this, updates.class);
        TaskStackBuilder stackBuilder = TaskStackBuilder.create(this);
        stackBuilder.addParentStack(updates.class);
        stackBuilder.addNextIntent(resultIntent);
        PendingIntent resultPendingIntent = 
            stackBuilder.getPendingIntent(
                0,
                PendingIntent.FLAG_UPDATE_CURRENT);
        mBuilder.setContentIntent(resultPendingIntent);
        NotificationManager mNotificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
        mNotificationManager.notify(124453245, mBuilder.build());

}

如何通过Firebase数据库通知用户？

1 个答案: