com.google.firebase.database.Query.addValueEventListener()方法的使用及代码示例

x33g5p2x  于2022-01-28 转载在 其他  
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本文整理了Java中com.google.firebase.database.Query.addValueEventListener方法的一些代码示例，展示了Query.addValueEventListener的具体用法。这些代码示例主要来源于Github/Stackoverflow/Maven等平台，是从一些精选项目中提取出来的代码，具有较强的参考意义，能在一定程度帮忙到你。Query.addValueEventListener方法的具体详情如下：
包路径：com.google.firebase.database.Query
类名称：Query
方法名：addValueEventListener

Query.addValueEventListener介绍

[英]Add a listener for changes in the data at this location. Each time time the data changes, your listener will be called with an immutable snapshot of the data.
[中]在此位置添加数据更改的侦听器。每次数据更改时，您的侦听器都会被调用一个不可变的数据快照。

代码示例

代码示例来源：origin: FrangSierra/RxFirebase

@Override
  public void subscribe(final FlowableEmitter<DataSnapshot> emitter) throws Exception {
    final ValueEventListener valueEventListener = new ValueEventListener() {
      @Override
      public void onDataChange(DataSnapshot dataSnapshot) {
        emitter.onNext(dataSnapshot);
      }
      @Override
      public void onCancelled(final DatabaseError error) {
        if (!emitter.isCancelled())
          emitter.onError(new RxFirebaseDataException(error));
      }
    };
    emitter.setCancellable(new Cancellable() {
      @Override
      public void cancel() throws Exception {
        query.removeEventListener(valueEventListener);
      }
    });
    query.addValueEventListener(valueEventListener);
  }
}, strategy);

代码示例来源：origin: yongjhih/rxfirebase

private void verifyQueryAddValueEventListener() {
  verify(mockQuery)
      .addValueEventListener(valueEventListener.capture());
}

代码示例来源：origin: UdacityAndroidDevScholarship/quiz-app

@Override
public void fetchResources(int startFrom, int limit, Callback<List<Resource>> callback) {
  ValueEventListener listener = new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot snapshot) {
      if (snapshot != null) {
        List<Resource> resources = new ArrayList<>();
        for (DataSnapshot childSnapshot : snapshot.getChildren()) {
          Resource resource = childSnapshot.getValue(Resource.class);
          resources.add(resource);
        }
        callback.onReponse(resources);
      }
    }
    @Override
    public void onCancelled(DatabaseError databaseError) {
      callback.onError();
    }
  };
  Query resourcesQuery = mResourcesRef.orderByChild(KEY_TIMESTAMP);
  if (limit > 0) {
    resourcesQuery.limitToFirst(limit);
  }
  resourcesQuery.addValueEventListener(listener);
  mValueListeners.add(listener);
}

代码示例来源：origin: TomGrill/gdx-firebase

@Override
public ValueEventListener addValueEventListener(final ValueEventListener listener) {
  com.google.firebase.database.ValueEventListener fbListener = new com.google.firebase.database.ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
      listener.onDataChange(new DesktopDataSnapshot(dataSnapshot));
    }
    @Override
    public void onCancelled(DatabaseError databaseError) {
      listener.onCancelled(new DesktopDatabaseError(databaseError));
    }
  };
  query.addValueEventListener(fbListener);
  fbValueEventListenerList.add(fbListener);
  valueEventListenerList.add(listener);
  return listener;
}

代码示例来源：origin: UdacityAndroidDevScholarship/quiz-app

quizzesRefQuery.limitToFirst(limitToFirst);
quizzesRefQuery.addValueEventListener(listener);
mValueListeners.add(listener);

代码示例来源：origin: UdacityAndroidBasicsScholarship/audacity

private void setHottestAppData() {
    mDbRef.child(Constants.HOTTEST_APP_STRING).limitToLast(1).addValueEventListener(new ValueEventListener() {
      @Override
      public void onDataChange(DataSnapshot dataSnapshot) {
        for (DataSnapshot snapshot : dataSnapshot.getChildren()) {
          HottestApp hottestApp = snapshot.getValue(HottestApp.class);
          mHottestAppTitle.setText(hottestApp.getAppTitle());
          mHottestStudentName.setText(hottestApp.getStudentName());
          mHottestPostedOn.setText(Helpers.formatDate(hottestApp.getPostedDate()));
          String profileImage = hottestApp.getProfileImage();
          if (profileImage != null) {
            Glide.with(mContext).load(profileImage).into(mHottestProfileImage);
          }
        }
      }

      @Override
      public void onCancelled(DatabaseError databaseError) {

      }
    });
  }
}

代码示例来源：origin: UdacityAndroidBasicsScholarship/audacity

private void setChallengeData() {
  mDbRef.child(Constants.CHALLENGES_STRING).limitToLast(1).addValueEventListener(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
      for (DataSnapshot snapshot : dataSnapshot.getChildren()) {
        Challenge challenge = snapshot.getValue(Challenge.class);
        mChallengeName.setText(challenge.getChallengeName());
        mChallengeModName.setText(challenge.getModeratorName());
        mChallengeEndDate.setText(Helpers.formatDate(challenge.getStartDate()));
        String profileImage = challenge.getProfileImage();
        if (profileImage != null) {
          Glide.with(mContext).load(profileImage).into(mChallengeProfileImage);
        }
      }
      mRootView.setVisibility(View.VISIBLE);
    }
    @Override
    public void onCancelled(DatabaseError databaseError) {
    }
  });
}

代码示例来源：origin: yongjhih/rxfirebase

@Override
  public void subscribe(
      @NonNull final ObservableEmitter<DataSnapshot> emit) throws Exception {
    final ValueEventListener listener = new ValueEventListener() {
      @Override
      public void onDataChange(DataSnapshot dataSnapshot) {
        if (!emit.isDisposed()) {
          emit.onNext(dataSnapshot);
        }
      }
      @Override
      public void onCancelled(DatabaseError e) {
        if (!emit.isDisposed()) {
          emit.onError(e.toException());
        }
      }
    };
    emit.setCancellable(new Cancellable() {
      @Override
      public void cancel() throws Exception {
        query.removeEventListener(listener);
      }
    });
    query.addValueEventListener(listener);
  }
});

代码示例来源：origin: UdacityAndroidBasicsScholarship/scholar-quiz

private void fetchChannelName(final String channelId){
  AppInfo.databaseReference.child("ChannelList").child(channelId).orderByKey()
      .addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot channelSnapshot) {
          LessonListModel lessonListModel = channelSnapshot.getValue(LessonListModel.class);
          String channelName = lessonListModel.getChannelName();
          getSupportActionBar().setTitle(channelName);
        }
        @Override
        public void onCancelled(DatabaseError databaseError) {
        }
      });
}

代码示例来源：origin: firebase/snippets-android

public void basicQueryValueListener() {
  String myUserId = getUid();
  Query myTopPostsQuery = databaseReference.child("user-posts").child(myUserId)
      .orderByChild("starCount");
  // [START basic_query_value_listener]
  // My top posts by number of stars
  myTopPostsQuery.addValueEventListener(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
      for (DataSnapshot postSnapshot: dataSnapshot.getChildren()) {
        // TODO: handle the post
      }
    }
    @Override
    public void onCancelled(DatabaseError databaseError) {
      // Getting Post failed, log a message
      Log.w(TAG, "loadPost:onCancelled", databaseError.toException());
      // ...
    }
  });
  // [END basic_query_value_listener]
}

代码示例来源：origin: FrangSierra/RxFirebase

@Test
public void testObserveListWithDataSnapshotCustomMapper() throws Exception {
  //noinspection unchecked
  Function<DataSnapshot, ChildData> mapper = (Function<DataSnapshot, ChildData>) mock(Function.class);
  doReturn(childData).when(mapper).apply(eq(dataSnapshot));
  TestSubscriber<List<ChildData>> testObserver = RxFirebaseDatabase
    .observeValueEvent(query, DataSnapshotMapper.listOf(ChildData.class, mapper))
    .test();
  ArgumentCaptor<ValueEventListener> argument = ArgumentCaptor.forClass(ValueEventListener.class);
  verify(query).addValueEventListener(argument.capture());
  argument.getValue().onDataChange(dataSnapshot);
  verify(mapper).apply(dataSnapshot);
  testObserver.assertNoErrors()
    .assertValueCount(1)
    .assertValueSet(Collections.singletonList(childDataList))
    .assertNotComplete()
    .dispose();
}

代码示例来源：origin: FrangSierra/RxFirebase

@Test
public void testObserveListWithDataSnapshotMapper() {
  TestSubscriber<List<ChildData>> testObserver = RxFirebaseDatabase
    .observeValueEvent(query, DataSnapshotMapper.listOf(ChildData.class))
    .test();
  ArgumentCaptor<ValueEventListener> argument = ArgumentCaptor.forClass(ValueEventListener.class);
  verify(query).addValueEventListener(argument.capture());
  argument.getValue().onDataChange(dataSnapshot);
  testObserver.assertNoErrors()
    .assertValueCount(1)
    .assertValueSet(Collections.singletonList(childDataList))
    .assertNotComplete()
    .dispose();
}

代码示例来源：origin: UdacityAndroidBasicsScholarship/scholar-quiz

.addValueEventListener(new ValueEventListener() {
  @Override
  public void onDataChange(DataSnapshot channelSnapshot) {

代码示例来源：origin: UdacityAndroidBasicsScholarship/scholar-quiz

private void attachToBeSubscribedChannelListner() {
      .addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot channelSnapshot) {

代码示例来源：origin: riggaroo/android-things-electricity-monitor

logsRef.limitToLast(1).addValueEventListener(new ValueEventListener() {
  @Override
  public void onDataChange(final DataSnapshot dataSnapshot) {

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