(Google translate)
Create listener to receive data from FirebaseRealtimeDatabase every time it changes.
Create listener to receive data from FirebaseRealtimeDatabase every time it changes.
B4X:
'en pagina Main
Sub DatosRecibidos_Fire(Value As String)'recibe un string en formato json
Dim parser As JSONParser
parser.Initialize(Value)
Dim RootFB As Map = parser.NextObject
If RootFB = Null Or RootFB.IsInitialized = False Then
'error
Else
'RootFB ...........
End If
End Sub
#If Java
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.ValueEventListener;
import anywheresoftware.b4a.keywords.B4AApplication;
import android.content.pm.PackageManager.NameNotFoundException;
public static class MyFirebaseListener {
private String NombreEvento = "DatosRecibidos";//nombre del evento que recibira los datos en pagina Main (OJO NO en B4XPages.MainPage)
// Enviar datos a B4A en mi caso Sub DatosRecibidos_Fire(Value As String) en pagina Main
public void NotificarDatosCambiados(String txt) throws IOException {
processBA.raiseEventFromUI(this, NombreEvento.toLowerCase(BA.cul) + "_fire", txt);//evento DatosRecibidos_Fire en pagina Main
}
FirebaseDatabase database = FirebaseDatabase.getInstance("https://tureferencia-xxxx.firebaseio.com/");//aqui tu referencia de RealtimeDatabase
DatabaseReference myRef = FirebaseDatabase.getInstance().getReference();//en este caso leo todos los datos (puedes leer el nodo que quieras)
public void IniciarListener() throws IOException {
myRef.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
//String name = dataSnapshot.toString();//leer como string
//BA.Log(name);//
try {
Map<String, Object> td = (HashMap<String, Object>) dataSnapshot.getValue();//leer datos
NotificarDatosCambiados(td.toString());//devolver datos a B4A
} catch(Exception e) {
BA.Log("ERROR");
}//catch
}//onDataChange
@Override
public void onCancelled(DatabaseError databaseError) {
BA.Log("Error al leer: " + databaseError.getCode());
}
});//myRef.addValueEventListener
}//IniciarListener()
}//MyFirebaseListener
#End If
'---------------------------------------------------------------------------------
en B4XPages.MainPage
'despues de haberte logeado en Firebase inicializar Listener
Sub IniciarFirebase
Dim streamMeta, jo As JavaObject
streamMeta = jo.InitializeNewInstance(Application.PackageName & ".main$MyFirebaseListener", Null)
streamMeta.RunMethod("IniciarListener",Null)
End Sub
'I am not very expert in Java, if someone can improve it ...... welcome.
