Android Firebase 存储，内部类下载到位图

Question

我在使用 Android 列表时遇到了一些问题。我有一种方法可以创建玩家列表，并从 firebase 数据库和存储中加载玩家。

有些玩家有头像，它们作为生成的key存储在storage/players/keyname中（玩家在数据库中唯一的key就是Firebase存储中的头像名称）。

我遇到的问题是当我尝试创建 OnSuccessListener/player 时。我似乎无法传递数据。

onSuccessListener 的问题：

• 外部的所有内容都被视为“外部类”，这意味着当我想创建一个播放器时，它无法读取 onsuccesslistener 中的数据。
• 内部的所有内容都不能将任何数据传递到侦听器之外。
• 我无法将其转换为位图

我需要能够使用来自侦听器和地图条目的数据创建“玩家 p”。到目前为止，我失败了（不能同时通过）。

//Method to create the list of players. To do: call again after adding new player
public void createPlayerList(){
    //The list of players that will be filled
    final List listPlayers = new ArrayList<Player>();

    //The path where all our players are stored.
    DatabaseReference ref = FirebaseDatabase.getInstance().getReference().child("users")
            .child( FirebaseAuth.getInstance().getCurrentUser().getUid() ).child("team").child("players");


    //Method that just gets called once
    ref.addListenerForSingleValueEvent(new ValueEventListener() {

        //dataSnapshot contains all data from the path to our players
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            Map<String, Object> players = (Map<String, Object>) dataSnapshot.getValue();

            //We return our player data in a map. Loop through each value in the map and create a player object for each player
            //And add that player object to our list of players

            //Create Storage instance
            FirebaseStorage storage = FirebaseStorage.getInstance();
            //Create storageReference
            final StorageReference storageRef = storage.getReferenceFromUrl("gs://bucket.appspot.com");

            // Create a reference to a file from a Google Cloud Storage URI
            StorageReference gsReference = storage.getReferenceFromUrl(storageRef + "/players/");


            for (Map.Entry<String, Object> entry : players.entrySet()){
                Map singlePlayer = (Map) entry.getValue();

                //Get unique key
                String key = entry.getKey();

                storageRef.child(key).getDownloadUrl().addOnSuccessListener(new OnSuccessListener<Uri>() {
                    @Override
                    public void onSuccess(Uri uri) {
                        //Picasso.with(getActivity()).load(uri).into(R.id.playerProfilePicture);
                    }
                }).addOnFailureListener(new OnFailureListener() {
                    @Override
                    public void onFailure(@NonNull Exception exception) {
                        // Handle any errors
                    }
                });

                //standard mage
                Bitmap profileBits = BitmapFactory.decodeResource(getResources(), R.drawable.player_icon);
                PlayersFragment.this.setProfilePicture(profileBits);

                //Create player
                Player p = new Player((String) singlePlayer.get("name"), (String) singlePlayer.get("preferredPosition"), profilePicture   );

                //Add player to list
                listPlayers.add(p);
            }
        }
        @Override
        public void onCancelled(DatabaseError databaseError) {
        }
    });

    //Add all results from database to our listview
    listViewPlayers = (ListView) fragmentView.findViewById(R.id.players_list);

    //Attach adapter to listview, to get a layout for each row
    listViewPlayers.setAdapter(new PlayerAdapter(getActivity(), R.layout.row_player_list_item, listPlayers));
    //Necessary for handling clicks
    listViewPlayers.setItemsCanFocus(true);

}

Answer 1

记住 addListenerForSingleValueEvent 会立即返回。您传递给它的侦听器将在一段时间后被调用。就目前而言，您似乎希望它在结果可用并且 listPlayers 完全填充之前一直阻塞。

相反，我建议在你的玩家列表被填充后立即在你的 onDataChange 回调中处理 listViewPlayers。

另请注意，gsReference 似乎并未在任何地方使用。你确定你不是想说gsReference.child(key).getDownloadUrl()... 来查看循环中每个找到的玩家的“玩家”文件夹吗？