当用户再次登录时，数据从Firebase数据库中删除
我创建了一个数据库，存储用户信息，如电子邮件、密码、纬度、经度和工厂位置plant location是指当用户点击地图时，该位置的纬度和经度会保存在plant location中
之前的数据库映像：
但当我注销当前用户，然后再次使用相同的电子邮件登录时，工厂位置被删除。正如你们现在可以看到的，工厂的位置和它的子节点被删除了
数据库之后：
请帮帮我
地图活动。爪哇
public class MapsActivity extends FragmentActivity implements OnMapReadyCallback,
NavigationView.OnNavigationItemSelectedListener,
AppCompatCallback {
private static final String Tag = "MapsActivity";
private GoogleMap mMap;
GeoFire geoFire;
SharedPrefrence mShared;
public AppCompatDelegate delegate;
private final float DEFAULT_ZOOM = 15f;
private static final String FINE_LOCATION = Manifest.permission.ACCESS_FINE_LOCATION;
private static final String COARSE_LOCATION = Manifest.permission.ACCESS_COARSE_LOCATION;
public Boolean mLocationPermissionGranted = false;
private static final int LOCATION_PERMISSION_REQUESTCODE = 1234;
public static DatabaseReference mReference,user_ref;
DrawerLayout drawerLayout;
boolean doubleBackToExitPressedOnce = false;
Toolbar tool;
FirebaseAuth mAuth;
ImageView img;
FirebaseAuth.AuthStateListener authStateListener;
ActionBarDrawerToggle actionBarDrawerToggle;
String userID;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
delegate = AppCompatDelegate.create(this, this);
delegate.onCreate(savedInstanceState);
delegate.setContentView(R.layout.activity_maps);
getlocationpermission();
mShared=new SharedPrefrence(this);
mAuth = FirebaseAuth.getInstance();
userID=mAuth.getCurrentUser().getUid();
img = findViewById(R.id.tree_button);
mReference = FirebaseDatabase.getInstance().getReference().child("UserData");
user_ref=FirebaseDatabase.getInstance().getReference().child("You");
tool = findViewById(R.id.toolbar);
delegate.setSupportActionBar(tool);
delegate.getSupportActionBar().setDisplayShowTitleEnabled(true);
drawerLayout = findViewById(R.id.drawer);
actionBarDrawerToggle = new ActionBarDrawerToggle(this, drawerLayout, R.string.open, R.string.close);
drawerLayout.addDrawerListener(actionBarDrawerToggle);
actionBarDrawerToggle.setDrawerIndicatorEnabled(true);//use for toggling navbar
actionBarDrawerToggle.syncState();
NavigationView navigationView = findViewById(R.id.navigation);
navigationView.setNavigationItemSelectedListener(this);
authStateListener = new FirebaseAuth.AuthStateListener() {
@Override
public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
if (firebaseAuth.getCurrentUser() == null) {
Toast.makeText(getApplicationContext(), "Logged Out", Toast.LENGTH_SHORT).show();
Intent i = new Intent(MapsActivity.this, Login.class);
i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
startActivity(i);
}
}
};
geoFire = new GeoFire(user_ref);
}
void initMap() {
SupportMapFragment supportMapFragment = (SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map);
supportMapFragment.getMapAsync(MapsActivity.this);
}
private void getlocationpermission() {
String[] permission = {Manifest.permission.ACCESS_FINE_LOCATION, Manifest.permission.ACCESS_COARSE_LOCATION};
if (ContextCompat.checkSelfPermission(this.getApplicationContext(), FINE_LOCATION) == PackageManager.PERMISSION_GRANTED) {
if (ContextCompat.checkSelfPermission(this.getApplicationContext(), COARSE_LOCATION) == PackageManager.PERMISSION_GRANTED) {
mLocationPermissionGranted = true;
initMap();
} else {
ActivityCompat.requestPermissions(this, permission, LOCATION_PERMISSION_REQUESTCODE);
}
}
}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
mLocationPermissionGranted = false;
switch (requestCode) {
case LOCATION_PERMISSION_REQUESTCODE: {
if (grantResults.length > 0) {
for (int i = 0; i < grantResults.length; i++) {
if (grantResults[i] != PackageManager.PERMISSION_GRANTED) {
mLocationPermissionGranted = true;
return;
}
}
mLocationPermissionGranted = true;
initMap();
}
}
}
}
private void getDeviceLocationMethod() {
Log.d(Tag, "getting the device location");
FusedLocationProviderClient mFusedLocationProviderClient = LocationServices.getFusedLocationProviderClient(this);
if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
return;
}
final Task<Location> location = mFusedLocationProviderClient.getLastLocation();
location.addOnCompleteListener(new OnCompleteListener<Location>() {
@Override
public void onComplete(@NonNull Task<Location> task) {
if (task.isSuccessful()) {
Location currentlocation = task.getResult();
User_Data user_data=new User_Data(mShared.getUser_pass(),mShared.getUser_email(),currentlocation.getLatitude(),
currentlocation.getLongitude());
mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(new LatLng(currentlocation.getLatitude(),
currentlocation.getLongitude()), DEFAULT_ZOOM));
DatabaseReference user=FirebaseDatabase.getInstance().getReference("UserData");
user.child(userID).setValue(user_data);
addMarker(new LatLng(currentlocation.getLatitude(), currentlocation.getLongitude()), mMap);
} else {
Toast.makeText(MapsActivity.this, "Error while finding the location" + task.getException(), Toast.LENGTH_SHORT).show();
}
}
});
}
@Override
public void onMapReady(GoogleMap googleMap) {
mMap = googleMap;
getDeviceLocationMethod();
if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION)
!= PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION)
!= PackageManager.PERMISSION_GRANTED) {
return;
}
mMap.setMyLocationEnabled(true);
location_to_firebase(googleMap);
}
private void location_to_firebase(final GoogleMap google_map) {
int height = 150;
int width = 150;
final BitmapDrawable bitmapdraw = (BitmapDrawable) getResources().getDrawable(R.drawable.icon);
Bitmap b = bitmapdraw.getBitmap();
final Bitmap smallMarker = Bitmap.createScaledBitmap(b, width, height, false);
google_map.setOnMapClickListener(new GoogleMap.OnMapClickListener() {
@Override
public void onMapClick(LatLng point) {
Marker marker = google_map.addMarker(new MarkerOptions().position(point));
marker.setIcon(BitmapDescriptorFactory
.fromBitmap(smallMarker));
final LatLng latLng = marker.getPosition();
final DatabaseReference newPost = mReference.child(userID);
newPost.child("plant location").push().setValue(latLng);
}
});
mReference.child(userID).child("plant location").addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
for(DataSnapshot s:dataSnapshot.getChildren()){
final LatLng lng = new LatLng(s.child("latitude").getValue(Double.class),
s.child("longitude").getValue(Double.class));
google_map.addMarker(new MarkerOptions().
position(lng).title(s.getKey())).setIcon(BitmapDescriptorFactory.fromBitmap(smallMarker));
google_map.addCircle(new CircleOptions().center(lng).radius(500).strokeColor(Color.TRANSPARENT));
}
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
}
登录。爪哇
public class Login extends AppCompatActivity {
EditText _email, _password;
Button _submit,_signup;
SharedPrefrence mShared;
private FirebaseAuth mAuth;
private static final int LOCATION_PERMISSION_REQUESTCODE=1234;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
_email = findViewById(R.id.email);
_password = findViewById(R.id.password);
_submit = findViewById(R.id.login);
_signup=findViewById(R.id.signup);
mShared=new SharedPrefrence(this);
_signup.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
startActivity(new Intent(Login.this,Signup.class));
}
});
mAuth = FirebaseAuth.getInstance();
_submit.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
startSignin();
}
});
runtimepermission();
}
private void startSignin() {
final String email = _email.getText().toString();
final String pass = _password.getText().toString();
if (TextUtils.isEmpty(email) || TextUtils.isEmpty(pass)) {
Toast.makeText(this, "Invalid Email or Password", Toast.LENGTH_SHORT).show();
} else {
mAuth.signInWithEmailAndPassword(email, pass).addOnCompleteListener(new OnCompleteListener<AuthResult>() {
@Override
public void onComplete(@NonNull Task<AuthResult> task) {
if (!task.isSuccessful()) {
Toast.makeText(Login.this, "SigninProblem", Toast.LENGTH_SHORT).show();
}
else
{
mShared.saveEmail(Login.this,email);
mShared.savePass(Login.this,pass);
Intent i=new Intent(Login.this,MapsActivity.class);
startActivity(i);
finish();
}
}
}).addOnCanceledListener(new OnCanceledListener() {
@Override
public void onCanceled() {
Toast.makeText(Login.this,"Login Canceled",Toast.LENGTH_LONG).show();
}
});
}
}
# 1 楼答案
当你重新登录时，问题并没有发生，而每次你的地图准备好时，问题都会发生。您在
onMapReady()方法中调用getDeviceLocationMethod()，这意味着每次地图准备就绪时，您都在创建一个新的User_Data对象，这意味着您正在覆盖数据库中的现有用户。这样plant location节点中的所有数据都会被删除。要解决这个问题，只需检查用户是否已经存在。如果没有，请将其添加到数据库中，否则不采取任何操作