问题
How can I get the all locations that are near to a passed GeoLocation(double lat, double lng) using Geo Queries.
I have the following code (and it happens nothing):
public void setCurrentLatLng(double lat, double lng){
this.lat = lat;
this.lng = lng;
GeoLocation geoLocation = new GeoLocation(lat, lng);
updateCurrenLocation(geoLocation);
GeoQuery geoQuery = geoFire.queryAtLocation(geoLocation, 8f);
geoQuery.addGeoQueryDataEventListener(new GeoQueryDataEventListener() {
@Override
public void onDataEntered(DataSnapshot dataSnapshot, GeoLocation location) {
Log.d("geoQuery","onDataEntered "+dataSnapshot.toString());
// ...
}
@Override
public void onDataExited(DataSnapshot dataSnapshot) {
Log.d("geoQuery","onDataExited "+dataSnapshot.toString());
// ...
}
@Override
public void onDataMoved(DataSnapshot dataSnapshot, GeoLocation location) {
Log.d("geoQuery","onDataMoved "+dataSnapshot.toString());
// ...
}
@Override
public void onDataChanged(DataSnapshot dataSnapshot, GeoLocation location) {
Log.d("geoQuery","onDataChanged "+dataSnapshot.toString());
// ...
}
@Override
public void onGeoQueryReady() {
// ...
Log.d("geoQuery","onGeoQueryReady");
}
@Override
public void onGeoQueryError(DatabaseError error) {
Log.d("geoQuery","onGeoQueryError");
// ...
}
});
this.setChanged();
notifyObservers();
this.clearChanged();
Log.d("update","clearChanged");
}
And this is my firebase data:
I think I'm open to modify the data struct if needed.
Logs
09-12 08:55:33.818 17710-17710/es.rchampa.weirdo D/geoQuery: lat=40.4430883 lng=-3.721805
09-12 08:55:33.982 17710-17710/es.rchampa.weirdo D/geoQuery: lat=40.4430883 lng=-3.721805
09-12 08:55:33.986 17710-17710/es.rchampa.weirdo D/geoQuery: onGeoQueryReady
09-12 08:55:34.025 17710-17710/es.rchampa.weirdo D/geoQuery: onGeoQueryReady
Gradle file
....
// Firebase
implementation 'com.google.firebase:firebase-database:16.0.1'
implementation 'com.google.firebase:firebase-storage:16.0.1'
implementation 'com.google.firebase:firebase-auth:16.0.3'
implementation 'com.google.firebase:firebase-crash:16.2.0'
implementation 'com.google.firebase:firebase-core:16.0.3'
// Firebase UI
implementation 'com.firebaseui:firebase-ui-database:1.2.0'
//Firebase GeoFire
implementation 'com.firebase:geofire-android:2.3.1'
// Google Play Services
implementation 'com.google.android.gms:play-services-auth:16.0.0'
implementation 'com.google.android.gms:play-services-maps:15.0.1'
implementation 'com.google.android.gms:play-services-location:15.0.1'
....
UPDATE
I can grant access to my private repo if you wish.
回答1:
you pass value 8f (float) as the radius there, while the the radius should rather be 8.0d or Double.valueOf(8.0), where MAX_SUPPORTED_RADIUS equals 8587 kilometers.
while the actual problem is, that GeoFire already would need to know of .child("location"), but it is not possible to represent that with a Reference; only DataSnapshot has getChildren().
the bottom line is:
you'd have to create a separate locations
Reference, in order to avoid the nesting. nevertheless you still can use the relateduidkey for these nodes (or at least add it as a child-node), in order to be able to look up within the usersReference. it's a1:1relation, in between twoReferences.
so here's a working Java example, just because ...
we're assuming the following structure (as described above):
{
"locations" : {
"CR88aa9gnDfJYYGq5ZTMwwC38C12" : {
".priority" : "9q8yywdgue",
"g" : "9q8yywdgue",
"l" : [ 37.7853889, -122.4056973 ]
}
},
"users" : {
"CR88aa9gnDfJYYGq5ZTMwwC38C12" : {
"displayName" : "user 01",
...
}
}
}
the database rules should have .indexOn for locations field g set:
{
"rules": {
...
"locations": {
".indexOn": "g"
}
}
}
the dependencies in the module's build.gradle:
dependencies {
...
implementation "com.firebase:geofire-android:2.3.1"
}
and this demonstrates, how to obtain a user's snapshot by a GeoQuery result;
notice the GeoQueryEventListener instead of the GeoQueryDataEventListener:
public class GeofireActivity extends AppCompatActivity {
private static final String LOG_TAG = GeofireActivity.class.getSimpleName();
private DatabaseReference refBase = null;
private DatabaseReference refLocation = null;
private DatabaseReference refUser = null;
private GeoFire geoFire = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.setContentView(R.layout.fragment_geofire);
this.setReferences();
}
private void setReferences() {
this.refBase = FirebaseDatabase.getInstance().getReference();
this.refUser = refBase.child("users");
this.refLocation = refBase.child("locations");
this.geoFire = new GeoFire(this.refLocation);
}
private void searchNearby(double latitude, double longitude, double radius) {
this.searchNearby(new GeoLocation(latitude, longitude), radius);
}
private void searchNearby(GeoLocation location, double radius) {
GeoQuery geoQuery = this.geoFire.queryAtLocation(location, radius);
geoQuery.addGeoQueryEventListener(new GeoQueryEventListener() {
@Override
public void onKeyEntered(String key, GeoLocation location) {
String loc = String.valueOf(location.latitude) + ", " + String.valueOf(location.longitude);
Log.d(LOG_TAG, "onKeyEntered: " + key + " @ " + loc);
/* once the key is known, one can lookup the associated record */
refUser.child(key).addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
Log.d(LOG_TAG, "onDataChange: " + dataSnapshot.toString());
}
@Override
public void onCancelled(@NonNull DatabaseError firebaseError) {
Log.e(LOG_TAG, "onCancelled: " + firebaseError.getMessage());
}
});
}
@Override
public void onKeyExited(String key) {
Log.d(LOG_TAG, "onKeyExited: " + key);
}
@Override
public void onKeyMoved(String key, GeoLocation location) {
Log.d(LOG_TAG, "onKeyMoved: " + key);
}
@Override
public void onGeoQueryReady() {
Log.d(LOG_TAG, "onGeoQueryReady");
}
@Override
public void onGeoQueryError(DatabaseError error) {
Log.e(LOG_TAG, "onGeoQueryError" + error.getMessage());
}
});
}
}
in order to maintain the integrity, one would need to remove the associated location record, when a user record is being removed - else it would result in keys, which cannot be looked up anymore.
回答2:
The Problem is When You Passed Radius According to Issue https://github.com/firebase/geofire-java/issues/72
double radius = 8589; // Fails
// double radius = 8587.8; //Passes
try to pass value like this this may helps
//GeoQuery geoQuery = geoFire.queryAtLocation(geoLocation, 8f);
GeoQuery geoQuery = geoFire.queryAtLocation(geoLocation, radius);
passing value 8f (float) as the radius, while the the radius should rather be 8.0d or Double.valueOf(8.0), where MAX_SUPPORTED_RADIUS equals 8587 kilometers.
回答3:
As it stands right now geofire sort of serves as an index to make geoqueries on, and provides the key of the document you want (which would be stored in a separate "collection").
You should be using geofire and a separate "collection" (call it usersLocations)
DatabaseReference ref = FirebaseDatabase.getInstance().getReference("usersLocations");
GeoFire geoFire = new GeoFire(ref);
Now you can use it as an index for your users, and can add items to it like so.
geoFire.setLocation('QymlMpC0Zc', new GeoLocation(40.2334983, -3.7185183));
Your Firebase RTDB will look like this now:
{
'users': {
'QymlMpC0Zc': {
// All your data here
}
},
'usersLocations': {
'QymlMpC0Zc': {
'g': 'ezjkgkk305',
'l': {
'0': 40.2334983,
'1': -3.7185183
}
}
}
}
So finally when you do a query on your geoFire you'll end up being firing whatever listeners you have.
As a small note... I am not a Java developer, but I do use/know geofire in general. Hopefully my bits of advice/thoughts will be helpful.
来源：https://stackoverflow.com/questions/52249425/geofire-not-found-locations