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这是一个在TV端使用RecyclerView的一个Demo，焦点效果是通过设置背景的方式实现的，非常简单，体验也非常好。

下面总结下在TV端使用使用RecyclerView时踩过的坑：

(一)解决RecyclerView刷新数据的时候，焦点错乱问题

（1） 允许adapter设置item id;

     setHasStableIds(true)

（2）adapter中复写getItemId方法；

      @Override
    public long getItemId(int position) {
        return position;
    }

（3）RecyclerView不允许item使用动画；

   setItemAnimator(null);

（二）解决长按遥控器，让RecyclerView快速滑动，焦点错乱问题

   （1）重写RecyclerView的dispatchKeyEvent方法，屏蔽RecyclerView的onKeyUp事件；
   （2）通过FocusFind类找到view，并让view请求焦点；
   （3）focusFind焦点失败之后，如果是让其滑动item的宽度（左后滑动）或者高度（上下滑动），然后return true；
 @Override
    public boolean dispatchKeyEvent(KeyEvent event) {
        if (mInterceptLister != null && mInterceptLister.onIntercept(event)) {
            return true;
        }

        boolean result = super.dispatchKeyEvent(event);
        View focusView = this.getFocusedChild();

        if (focusView == null) {
            return result;
        } else {

            if (event.getAction() == KeyEvent.ACTION_UP) {
                return true;
            } else {
                switch (event.getKeyCode()) {
                    case KeyEvent.KEYCODE_DPAD_RIGHT:
                        View rightView = FocusFinder.getInstance().findNextFocus(this, focusView, View.FOCUS_RIGHT);
                        mLogger.i("rightView is null:" + (rightView == null));
                        if (rightView != null) {
                            rightView.requestFocus();
                            return true;
                        } else {
                            return true;
                        }
                    case KeyEvent.KEYCODE_DPAD_LEFT:
                        View leftView = FocusFinder.getInstance().findNextFocus(this, focusView, View.FOCUS_LEFT);
                        mLogger.i("leftView is null:" + (leftView == null));
                        if (leftView != null) {
                            leftView.requestFocus();
                            return true;
                        } else {
                            return true;
                        }
                    case KeyEvent.KEYCODE_DPAD_DOWN:
                        View downView = FocusFinder.getInstance().findNextFocus(this, focusView, View.FOCUS_DOWN);
                        mLogger.i(" downView is null:" + (downView == null));
                        if (downView != null) {
                            downView.requestFocus();
                            return true;
                        } else {
                            return true;
                        }
                    case KeyEvent.KEYCODE_DPAD_UP:
                        View upView = FocusFinder.getInstance().findNextFocus(this, focusView, View.FOCUS_UP);
                        mLogger.i("upView is null:" + (upView == null));
                        if (event.getAction() == KeyEvent.ACTION_UP) {
                            return true;
                        } else {
                            if (upView != null) {
                                upView.requestFocus();
                                return true;
                            } else {
                                return true;
                            }

                        }
                }

            }

        }
        return result;
    }

（三）解决RecyclerView 定位到某个item不获取焦点问题

     RecyclerView定位到特定的child后，让其该view请求焦点

public class TvGridLayoutManager extends GridLayoutManager {

    public TvGridLayoutManager(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
    }

    public TvGridLayoutManager(Context context, int spanCount) {
        super(context, spanCount);
    }

    public TvGridLayoutManager(Context context, int spanCount, int orientation, boolean reverseLayout) {
        super(context, spanCount, orientation, reverseLayout);
    }

    /**
     * Base class which scrolls to selected view in onStop().
     */
    abstract class GridLinearSmoothScroller extends LinearSmoothScroller {

        public GridLinearSmoothScroller(Context context) {
            super(context);
        }

        /**
         * 滑动完成后,让该targetPosition 处的item获取焦点
         */
        @Override
        protected void onStop() {
            super.onStop();
            View targetView = findViewByPosition(getTargetPosition());

            if (targetView != null) {
                targetView.requestFocus();
            }
            super.onStop();
        }

    }

    /**
     * RecyclerView的smoothScrollToPosition方法最终会执行smoothScrollToPosition
     * @param recyclerView
     * @param state
     * @param position
     */
    @Override
    public void smoothScrollToPosition(RecyclerView recyclerView, RecyclerView.State state,
                                       int position) {
        GridLinearSmoothScroller linearSmoothScroller =
                new GridLinearSmoothScroller(recyclerView.getContext()) {
                    @Override
                    public PointF computeScrollVectorForPosition(int targetPosition) {
                        return computeVectorForPosition(targetPosition);
                    }
                };
        linearSmoothScroller.setTargetPosition(position);
        startSmoothScroll(linearSmoothScroller);
    }

    public PointF computeVectorForPosition(int targetPosition) {
        return super.computeScrollVectorForPosition(targetPosition);
    }

}