添加Firebase子項時在Android中獲取通知

Question

我試圖在使用偵聽器將Fire base數據庫子項添加到數據庫時嘗試獲取android通知，但無法獲取通知。我編寫了這個小測試應用程序，它不會在應用程序運行時顯示通知，甚至在後臺顯示。有人可以看看這個，並幫助我，我仍然是一個初學者，一點幫助將是美好的！

package com.fayaz.firebasenotify; 

import android.content.Context; 
import android.support.v7.app.AppCompatActivity; 
import android.os.Bundle; 
import android.util.Log; 
import com.google.firebase.auth.FirebaseAuth; 
import com.google.firebase.database.DataSnapshot; 
import com.google.firebase.database.DatabaseError; 
import com.google.firebase.database.DatabaseReference; 
import com.google.firebase.database.FirebaseDatabase; 
import com.google.firebase.database.ValueEventListener; 
import android.app.NotificationManager; 
import android.support.v4.app.NotificationCompat; 
import android.view.View; 


public class MainActivity extends AppCompatActivity { 

private FirebaseDatabase myFirebaseRef = FirebaseDatabase.getInstance(); 
private DatabaseReference myRef = myFirebaseRef.getReference(); 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 

} 

NotificationCompat.Builder builder = new NotificationCompat.Builder(this); 

public void sendNotification(View view) { 
    ValueEventListener valueEventListener = new ValueEventListener() { 
     @Override 
     public void onDataChange(DataSnapshot dataSnapshot) { 
      builder.setSmallIcon(R.mipmap.ic_launcher); 
      builder.setContentTitle("Firebase Push Notification"); 
      builder.setContentText("Hello this is a test Firebase notification, a new database child has been added"); 
      NotificationManager notificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE); 
      notificationManager.notify(1, builder.build()); 
     } 

     @Override 
     public void onCancelled(DatabaseError databaseError) { 
      Log.i("FirebaseError", databaseError.getMessage()); 
     } 

    }; 
    myRef.addValueEventListener(valueEventListener); 
} 
} 

Answer 1

你應該使用ChildEventListener，

super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
    mRootRef = FirebaseDatabase.getInstance().getReference(); 
    builder = new NotificationCompat.Builder(this); 
    mRootRef.addChildEventListener(new ChildEventListener() { 
     @Override 
     public void onChildAdded(DataSnapshot dataSnapshot, String s) { 
      builder.setSmallIcon(R.mipmap.ic_launcher); 
      builder.setContentTitle("Firebase Push Notification"); 
      builder.setContentText("Hello this is a test Firebase notification, a new database child has been added"); 
      NotificationManager notificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE); 
      notificationManager.notify(1, builder.build()); 
     } 

     @Override 
     public void onChildChanged(DataSnapshot dataSnapshot, String s) { 

     } 

     @Override 
     public void onChildRemoved(DataSnapshot dataSnapshot) { 

     } 

     @Override 
     public void onChildMoved(DataSnapshot dataSnapshot, String s) { 

     } 

     @Override 
     public void onCancelled(DatabaseError databaseError) { 

     } 
    }); 

確保您可以從數據庫中讀取數據（檢查安全規則）。