Java ValueEventListener类代码示例

import com.google.firebase.database.ValueEventListener; //导入依赖的package包/类
@Override
public void getMessages(final User u, final DatabaseCallback<List<Message>> dbCallback) {

    ValueEventListener listener = new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            List<Message> messages = new ArrayList<>();
            if (dataSnapshot.getChildrenCount() > 0) {
                for (DataSnapshot s : dataSnapshot.getChildren()) {
                    messages.add(s.getValue(Message.class));
                }
            }
            dbReference.child(u.getUid())
                    .child(MESSAGES).removeEventListener(this);
            dbCallback.onSuccess(messages);
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {
            dbCallback.onFailure(databaseError.toException());
        }
    };
    dbReference.child(u.getUid())
            .child(MESSAGES)
            .addValueEventListener(listener);
}
 

import com.google.firebase.database.ValueEventListener; //导入依赖的package包/类
public static List<Product> getAllProductes(){
        
    final List<Product> Productes=new ArrayList<Product>();    
        
// Attach a listener to read the data at our posts reference
ProductRef.addValueEventListener(new ValueEventListener() {
    
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        Product post = dataSnapshot.getValue(Product.class);
        Productes.add(post);
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {
        System.out.println("The read failed: " + databaseError.getCode());
    }
});
        
return Productes;
    }
 

import com.google.firebase.database.ValueEventListener; //导入依赖的package包/类
public Observable<Void> push() {
    final DatabaseReference child = easyFirebaseDb.databaseReference.child(name);
    for (Map.Entry<String, Object> entry : values.entrySet()) {
        child.child(entry.getKey()).setValue(entry.getValue());
    }
    return Observable.create(new Observable.OnSubscribe<Void>() {
                                 @Override
                                 public void call(final Subscriber<? super Void> subscriber) {
                                     child.addListenerForSingleValueEvent(new ValueEventListener() {
                                         @Override
                                         public void onDataChange(DataSnapshot dataSnapshot) {
                                             subscriber.onNext(null);
                                             subscriber.onCompleted();
                                         }

                                         @Override
                                         public void onCancelled(DatabaseError databaseError) {
                                             subscriber.onError(databaseError.toException());
                                         }
                                     });
                                 }
                             });
}
 

import com.google.firebase.database.ValueEventListener; //导入依赖的package包/类
@Test
public void canGetProfilePicUrl() {
    final String testUserForPic = "Test User for Pic";
    final String url = "http://url.test.ch";
    firebaseHelper.addOrUpdateUser(TEST_USER, testUserForPic);
    firebaseHelper.setOrUpdateProfilePicUrl(testUserForPic, url);
    firebaseHelper.getProfilePicUrl(testUserForPic, new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            String fetchedUrl = (String) dataSnapshot.getValue();
            Assert.assertTrue(url.equals(fetchedUrl));
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {
            throw databaseError.toException();
        }
    });
}
 

import com.google.firebase.database.ValueEventListener; //导入依赖的package包/类
public void notifyContactsOfConnectionChange(final boolean online, final boolean signoff) {
    final String myEmail = getAuthUserEmail();
    getMyContactsReference().addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot snapshot) {
            for (DataSnapshot child : snapshot.getChildren()) {
                String email = child.getKey();
                DatabaseReference reference = getOneContactReference(email, myEmail);
                reference.setValue(online);
            }
            if (signoff){
                FirebaseAuth.getInstance().signOut();
            }
        }

        @Override
        public void onCancelled(DatabaseError firebaseError) {
        }
    });
}
 

import com.google.firebase.database.ValueEventListener; //导入依赖的package包/类
public <T> Observable<T> getObjects(final Query query, final Class<T> objectClass, final boolean useRootElement) {
    return Observable.create(new Observable.OnSubscribe<T>() {
        @Override
        public void call(final Subscriber<? super T> subscriber) {
            query.addListenerForSingleValueEvent(new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {
                    if(useRootElement) {
                        converter.convert(dataSnapshot, objectClass, subscriber);
                    } else {
                        for (DataSnapshot entry : dataSnapshot.getChildren()) {
                            converter.convert(entry, objectClass, subscriber);
                        }
                    }
                    subscriber.onCompleted();
                }

                @Override
                public void onCancelled(DatabaseError databaseError) {

                }
            });
        }
    });
}
 

import com.google.firebase.database.ValueEventListener; //导入依赖的package包/类
/**
 * Add a new user
 * @param userId - the user's ID
 * @param name - the user's name
 * @param email - the user's email
 */
public void addUserRecords(final String userId, final String name, final String email) {
    mDatabase.child("users").child(userId).addListenerForSingleValueEvent(new ValueEventListener() {
        /**
         * Handle data change event
         * @param snapshot - current database contents
         */
        @Override
        public void onDataChange(DataSnapshot snapshot) {
            if (!snapshot.exists()) {
                User user = new User(userId, name, email, 0);
                mDatabase.child("users").child(userId).setValue(user);
            }
        }

        /**
         * Do nothing when the process is cancelled
         * @param databaseError - Ignored error
         */
        @Override
        public void onCancelled(DatabaseError databaseError) {
        }
    });
    setMemberData();
}
 

import com.google.firebase.database.ValueEventListener; //导入依赖的package包/类
@Test
public void testSubscribeThenUnsubscribeWithoutProblems()
    throws InterruptedException {
  DatabaseReference ref = IntegrationTestUtils.getRandomNode(masterApp) ;

  ValueEventListener listener =
      new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot snapshot) {}

        @Override
        public void onCancelled(DatabaseError error) {
          fail("Should not be cancelled");
        }
      };

  ValueEventListener listenerHandle = ref.addValueEventListener(listener);
  ZombieVerifier.verifyRepoZombies(ref);
  ref.removeEventListener(listenerHandle);
  ZombieVerifier.verifyRepoZombies(ref);
  ValueEventListener listenerHandle2 = ref.addValueEventListener(listener);
  ZombieVerifier.verifyRepoZombies(ref);
  ref.removeEventListener(listenerHandle2);
  ZombieVerifier.verifyRepoZombies(ref);
}
 

import com.google.firebase.database.ValueEventListener; //导入依赖的package包/类
private Observable<DataSnapshot> observe(final Query ref) {
    return Observable.create(emitter -> {
        final ValueEventListener listener =
                ref.addValueEventListener(new ValueEventListener() {
                    @Override public void onDataChange(DataSnapshot dataSnapshot) {
                        emitter.onNext(dataSnapshot);
                    }

                    @Override public void onCancelled(DatabaseError databaseError) {
                        emitter.onError(new FirebaseException(databaseError.getMessage()));
                    }
                });

        emitter.setCancellable(() -> ref.removeEventListener(listener));
    });
}
 

import com.google.firebase.database.ValueEventListener; //导入依赖的package包/类
@Test
public void testAttachingListener() {
  DatabaseReference ref = IntegrationTestUtils.getRandomNode(masterApp);

  ValueEventListener listener = ref.limitToLast(1)
      .addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot snapshot) {
          // No-op
        }

        @Override
        public void onCancelled(DatabaseError error) {
        }
      });

  assertNotNull(listener);
}
 

import com.google.firebase.database.ValueEventListener; //导入依赖的package包/类
public void removeDetectiveProcess(ViewAppHolder.UserProfileViewHolder userProfileViewHolder,
                                   Context context){
    FirebaseHelper.getUserAccountSettings(USER_LINK_FIREBASE)
            .child(Constants.DETECTION_MODE).setValue(Constants.USER_DETECTION_INACTIVE);

    userProfileViewHolder.DETECTION_ICON.setImageTintList(
            context.getResources().getColorStateList(R.color.safe_color));

    FirebaseHelper.getUserFriendList(USER_LINK_FIREBASE)
            .addListenerForSingleValueEvent(new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {
                    for(DataSnapshot dataSnapshot1 : dataSnapshot.getChildren()){
                        FirebaseHelper.getUserDetection(Utility.encodeUserEmail(dataSnapshot1.getValue(String.class)))
                                .child(USER_LINK_FIREBASE).removeValue();
                    }
                    FirebaseHelper.getUserLocation(USER_LINK_FIREBASE)
                            .removeEventListener(userDetectionLocationListener);
                }

                @Override
                public void onCancelled(DatabaseError databaseError) {

                }
            });
}
 

import com.google.firebase.database.ValueEventListener; //导入依赖的package包/类
private void displayCityStateCountry() {
    dbHelper.getDb().getReference( dbHelper.getUserPath() ).child( currUserID ).addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            for ( DataSnapshot field : dataSnapshot.getChildren() ) {
                switch ( field.getKey() ) {
                    case "city":
                        cityEditText.setText( ( field.getValue() != null ) ? field.getValue().toString() : "" );
                        break;
                    case "state":
                        stateEditText.setText( ( field.getValue() != null ) ? field.getValue().toString() : "" );
                        break;
                    case "country":
                        countryEditText.setText( ( field.getValue() != null ) ? field.getValue().toString() : "" );
                        break;
                }
            }
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {}
    });
}
 

import com.google.firebase.database.ValueEventListener; //导入依赖的package包/类
private void removeFriendRequestAFromB(final String USER_A_EMAIL, final String USER_B_EMAIL){
    FirebaseHelper.getUserFriendRequestList(Utility.encodeUserEmail(USER_B_EMAIL))
            .addListenerForSingleValueEvent(new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {
                    for(DataSnapshot dataSnapshot1 : dataSnapshot.getChildren()){
                        if(dataSnapshot1.getValue().equals(USER_A_EMAIL)){
                            FirebaseHelper.getUserFriendRequestList(Utility.encodeUserEmail(USER_B_EMAIL))
                                    .child(dataSnapshot1.getKey()).removeValue();
                            break;
                        }
                    }
                }

                @Override
                public void onCancelled(DatabaseError databaseError) {

                }
            });
}
 

import com.google.firebase.database.ValueEventListener; //导入依赖的package包/类
@Test
public void listenUserAvailabilityCorrectlyAttachesListener() {
    firebaseHelper.setUserAvailable(TEST_USER, false, true);
    ValueEventListener listener = new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            Assert.assertTrue(dataSnapshot.exists());
            Assert.assertTrue((boolean)dataSnapshot.getValue());
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    };

    firebaseHelper.listenUserAvailability(TEST_USER, false,  listener);
}
 

import com.google.firebase.database.ValueEventListener; //导入依赖的package包/类
@Test
public void testUpdateAfterSetLeafNodeWorks() throws InterruptedException {
  DatabaseReference ref = IntegrationTestUtils.getRandomNode(masterApp);
  final Semaphore semaphore = new Semaphore(0);
  final Map<String, Object> expected = new MapBuilder().put("a", 1L).put("b", 2L).build();

  ref.addValueEventListener(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot snapshot) {
      if (DeepEquals.deepEquals(snapshot.getValue(), expected)) {
        semaphore.release();
      }
    }

    @Override
    public void onCancelled(DatabaseError error) {
    }
  });
  ref.setValueAsync(42);
  ref.updateChildrenAsync(expected);

  TestHelpers.waitFor(semaphore);
}