如何从firebase数据中获取特定键值？

我假设DIV_1的父级和DIV_10是root.如果你有DIV_ID类似"1"或"10"的值并且需要获得值DIV_NAME,那么你应该这样做:

int divId = 1; // sample
FirebaseDatabase.getInstance().getReference().orderByChild("DIV_ID").equalTo(divId)
    .addValueEventListener(new ValueEventListener() {
        ... onDataChange(DataSnapshot dataSnapshot) {
             for (DataSnapshot snapshot : dataSnapshot.getChildren()) {
                 String divName = snapshot.child("DIV_NAME").getValue(String.class);
                 // there you go
                 // and please check if you have more than 1 value as result
             }
        }
        ...
    }

但是,如果你有一个像键值DIV_1还是DIV_10那么它应该是容易得多.像这样:

String key = "DIV_1";
FirebaseDatabase.getInstance().getReference(key)
    .addValueEventListener(new ValueEventListener() {
        ... onDataChange(DataSnapshot dataSnapshot) {
             String divName = snapshot.child("DIV_NAME").getValue(String.class);
             // note that in this sample, it doesn't need to loop, because:
             // data you get here is one level deeper than data you got on first sample
        }
        ...
    }

希望这可以帮助

我假设DIV_1的父级和DIV_10是root.如果你有DIV_ID类似"1"或"10"的值并且需要获得值DIV_NAME,那么你应该这样做:

int divId = 1; // sample
FirebaseDatabase.getInstance().getReference().orderByChild("DIV_ID").equalTo(divId)
    .addValueEventListener(new ValueEventListener() {
        ... onDataChange(DataSnapshot dataSnapshot) {
             for (DataSnapshot snapshot : dataSnapshot.getChildren()) {
                 String divName = snapshot.child("DIV_NAME").getValue(String.class);
                 // there you go
                 // and please check if you have more than 1 value as result
             }
        }
        ...
    }

但是,如果你有一个像键值DIV_1还是DIV_10那么它应该是容易得多.像这样:

String key = "DIV_1";
FirebaseDatabase.getInstance().getReference(key)
    .addValueEventListener(new ValueEventListener() {
        ... onDataChange(DataSnapshot dataSnapshot) {
             String divName = snapshot.child("DIV_NAME").getValue(String.class);
             // note that in this sample, it doesn't need to loop, because:
             // data you get here is one level deeper than data you got on first sample
        }
        ...
    }

希望这可以帮助