问题
I'm creating a online mess application where there are two logins one for mess owner and another for user so when mess owner put location in his data there should be marker on map in user side.
here is structure of database in imageDatabase structure
please suggest me code to access those latitude n longitude values and create marker on map for each mess registered with location values.
回答1:
EDITED Am proposing a small adjustment to the database structure...under 'MessProviders' create another node called 'locations' with the userID,mProviderLatitude,mProviderLongitude, mProviderBrandName. . It would be good if you had a separate class for getters and setters. My class for that is 'CordinatesModel'
private void messLocation() {
DatabaseReference currentDBcordinates = FirebaseDatabase.getInstance().getReference().child("Users").child("MessProviders").child("locations");
currentDBcordinates.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
//Create an array of markers
int size = (int) dataSnapshot.getChildrenCount(); //
Marker[] allMarkers = new Marker[size];
mMap.clear(); //Assuming you're using mMap
for(DataSnapshot ds : dataSnapshot.getChildren()) {
//Specify your model class here
CordinatesModel cordinatesModel = new CordinatesModel();
//lets create a loop
for(int i=0;i<=size;i++) {
try {
//assuming you've set your getters and setters in the Model class
cordinatesModel.setmProviderLatitude(s.getValue(CordinatesModel.class).getmProviderLatitude());
cordinatesModel.setmProviderLongitude(s.getValue(CordinatesModel.class).getmProviderLongitude());
cordinatesModel.setmProviderBrandName(s.getValue(CordinatesModel.class).getmProviderBrandName());
//lets retrieve the coordinates and other information
Double latitude1 = cordinatesModel.getmProviderLatitude();
Double longitude1 = cordinatesModel.getmProviderLongitude();
String brandName=cordinatesModel.getmProviderBrandName();
//convert the coordinates to LatLng
LatLng latLng = new LatLng(latitude1, longitude1);
mMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);
//Now lets add updated markers
//lets add updated marker
allMarkers[i] = mMap.addMarker(new MarkerOptions()
.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_RED)).position(latLng).title(brandName));enter code here
}catch (Exception ex){}
}
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
回答2:
You can have a root and select it. Then Retrieve all your lat/lng in your snapshot within that root. Here is a sample code:
DatabaseReference locationRef = mRootRef.child("locations");
locationRef.addValueEventListener(new com.firebase.client.ValueEventListener() {
@Override
public void onDataChange(com.firebase.client.DataSnapshot dataSnapshot) {
for (DataSnapshot snapm: dataSnapshot.getChildren()) {
Double latitude = snapm.child("0").getValue(Double.class);
Double longitude = snapm.child("1").getValue(Double.class);
}
}
@Override
public void onCancelled(FirebaseError firebaseError) {
throw firebaseError.toException();
}
});
回答3:
mDb = FirebaseDatabase.getInstance().getReference().child("Users").child("MessProviders").child("zZvkbgUbFohCwtYRfORUM0DBSZR2").child("ProfileInformation");
mDb.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
String name = dataSnapshot.child("mProviderBrandName").getValue(String.class);
double latt = dataSnapshot.child("mProviderLatitude").getValue(Double.class);
double lngg = dataSnapshot.child("mProviderLongitude").getValue(Double.class);
mMap.addMarker(new MarkerOptions().position(new LatLng(latt, lngg)).title(name));
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
this is the code that worked to put marker on map but problem is I'm providing user id manually so i will create only one marker but i want to create marker for every user how can system will take user id and create marker for each user id ??
来源：https://stackoverflow.com/questions/49324085/retrieve-location-from-firebase-and-put-marker-on-google-map-api-for-android-app