文档唯一id的Android Firestore搜索集合

FirebaseFirestore db = FirebaseFirestore.getInstance();
DocumentReference docRef = db.collection("collectionName").document("documentId");

docRef.get().addOnSuccessListener(new OnSuccessListener<DocumentSnapshot>() {
    @Override
    public void onSuccess(DocumentSnapshot documentSnapshot) {
        if (documentSnapshot.exists()) {
            // 文档存在，可以获取数据
            Object data = documentSnapshot.getData();
        } else {
            // 文档不存在
        }
    }
});

FirebaseFirestore db = FirebaseFirestore.getInstance();
Query query = db.collection("collectionName").whereEqualTo(FieldPath.documentId(), "documentId");

query.get().addOnSuccessListener(new OnSuccessListener<QuerySnapshot>() {
    @Override
    public void onSuccess(QuerySnapshot querySnapshot) {
        for (DocumentSnapshot documentSnapshot : querySnapshot) {
            // 处理匹配的文档
            Object data = documentSnapshot.getData();
        }
    }
});