Android TV Leanback分析之ObjectAdap

ObjectAdapter提供对数据模型的访问，其内部有观察者，数据的改变，会通知UI更新。ObjectAdapter是一个抽象类，其实现还得看ArrayObjectAdapter或CursorObjectAdapter

    //设置PresenterSelector
    public ObjectAdapter(PresenterSelector presenterSelector) {
        setPresenterSelector(presenterSelector);
    }
     //设置Presenter，会转化为SinglePresenterSelector
    public ObjectAdapter(Presenter presenter) {
        setPresenterSelector(new SinglePresenterSelector(presenter));
    }
    //设置PresenterSelector通过item获取对应的Presenter
    public final Presenter getPresenter(Object item) {
        if (mPresenterSelector == null) {
            throw new IllegalStateException("Presenter selector must not be null");
        }
        return mPresenterSelector.getPresenter(item);
    }
   //需要子类实现
   public abstract Object get(int position);

ArrayObjectAdapter 主要提供了一个实体列表，提供了一系列数据列表更新的方法：add 、addAll、remove、move、replace、removeItems、clear、setItems，setItems通过实现DiffCallback可以局部更新数据。

    private final List<Object> mItems = new ArrayList<>();

    //在ItemBridgeAdapter中 ObjectAdapter就是通过此方法拿到具体的item
    @Override
    public Object get(int index) {
        return mItems.get(index);
    }