Android Firebase存储，内部类下载到位图

Question

我在Android列表中遇到了一些问题。我有一个方法，创建一个播放器列表，并从firebase数据库和存储加载播放器。

一些球员有个人资料照片，他们被存储在storage/players/keyname中作为生成的密钥(一个球员在数据库中的唯一密钥是Firebase存储中的个人资料名称)。

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:

问题

• 外部的所有东西都被认为是"outerclass"，这意味着当我想创建一个播放器时，它不能读取onsuccesslistener中的数据。
• 内部的所有内容都不能向监听器外部传递任何数据。
• 我无法将其转换为位图

我需要能够从监听器和地图条目的数据创建"玩家p"。到目前为止，我都不及格(两门都过不了)。

//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。传递给它的侦听器将在稍后被调用。从现在的情况来看，看起来你希望它阻塞，直到结果可用，listPlayers被完全填充。

相反，我建议处理listViewPlayers从你的ondatachchange回调，在你的球员列表被填充后立即。

还要注意gsReference似乎没有在任何地方使用。你确定你的意思不是说gsReference.child(key).getDownloadUrl()...在"players"文件夹下查找每个在循环中找到的玩家吗?