从Firebase导入Java类

Question

我了解如何使用以下代码将类推送到Firebase：

WeekViewEvent event = new WeekViewEvent();        
DatabaseReference myRef = database.getReference();
myRef.child("Events").push().setValue(event);

我想知道将此类（或基于id或字段的任何其他类）检索回Android的最简单方法是什么？ 我敢肯定有一种简单的方法，但是到目前为止，我发现的所有方法都不起作用：

    public void importSchedule(String ownerName){
    DatabaseReference events = FirebaseDatabase.getInstance().getReference("Events");

    Query allOwnersEvents = events.equalTo(ownerName);

    allOwnersEvents.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            for (DataSnapshot post : dataSnapshot.getChildren()) {
                WeekViewEvent allDay = post.child(WeekViewEvent.class); // This doesn't compile, as the type needs to be String
            }
        }
        public void onCancelled(DatabaseError databaseError) {}
    });

WeekViewEvent对象具有以下变量：

public class WeekViewEvent {
    private long mId;
    private Calendar mStartTime;
    private Calendar mEndTime;
    private String mName;
    private String mLocation;
    private int mColor;
    private boolean mAllDay;
    private String owner;

    //setters and getters
}

在我的Firebase中，我要查询的对象是：

Events{
 -siX1hB9k-HpCmfO3n:{
    allDay:"false",
    color:"-477870",
    endTime:{
      endHour:4,
      endMinute:10,
      ...},
    id: 1,
    location:"location",
    name: "hi",
    owner: "a@a.ca",
    startTime:{
      startHour:3,
      startMinute:45,
      ...}
    }
}

Answer 1

您可以尝试以下方法来检索您的类的对象

Map<String, Object> eventMap;
for(DataSnapshot da :dataSnapshot.getChildren())
{
    if (da.getValue() instanceof Map) {
        eventMap = (HashMap<String, Object>)
                da.getValue();
        Map<String, Object> eventMap = weekMap;
        WeekViewEvent event = new WeekViewEvent();
    }
}

Answer 2

要解决此问题，请使用以下代码：

DatabaseReference myRef = database.getReference();
DatabaseReference myNewRef = myRef.child("Events").push();
String pushedKey = myNewRef.getKey();
myNewRef.setValue(event);

并取回数据：

public void importSchedule(String ownerName){

    DatabaseReference events = FirebaseDatabase.getInstance().getReference("Events").child(pushedKey);
    Query allOwnersEvents = events.equalTo(ownerName);

    allOwnersEvents.addValueEventListener(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        for (DataSnapshot post : dataSnapshot.getChildren()) {
        String allDay = post.child("yourFiedName").getValue(String.class);
        }
    }
    public void onCancelled(DatabaseError databaseError) {}
});

其中yourFiedName是所需字段的名称。 希望能帮助到你。