从Firebase引用重新创建datasnapshot

Question

    DatabaseReference ref = FirebaseDatabase.getInstance().getReference();
    Log.i(TAG_FIREBASE_READER_HIGHSCORE , ref.child("highscore-list").toString());

    ref.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            Log.i(TAG_FIREBASE_READER_HIGHSCORE , "entered onDataChange for FirebaseReader");
            Toast.makeText(fromContext, "Reading online highscores, please wait...", Toast.LENGTH_LONG).show();

            for (DataSnapshot snapshot : dataSnapshot.getChildren()){
                Log.i(TAG_FIREBASE_READER_HIGHSCORE, "found child " + snapshot.toString());
            }
        }
        @Override
        public void onCancelled(DatabaseError databaseError) {
            Log.i(TAG_FIREBASE_READER_HIGHSCORE, "onCancelled was called");
        }

    });

{
  "rules": {
    "users": {
      "$uid": {
        ".read": true,
        ".write": true
      }
    }
  }
}

如果这不起作用，我如何从数据库中实际检索任何数据？

Answer 1

>

确保您有internet连接权限

如果您没有为路径指定特定的安全规则，Firebase会自动拒绝acess，因此，如果您没有使用安全规则从用户那里读取数据，它将失败

{“规则”：{“.读”：true,“.写”：true}}