Android(安卓)TV应用 RecyclerView 焦点乱跑问题解决

本文只讨论如何解决Android TV应用 RecyclerView 焦点乱跑的问题.

RecyclerView的使用方法，大家可以参考此篇博文：http://blog.csdn.net/lmj623565791/article/details/45059587

使用示例：

public static final int ITEMS_COUNT_ONE_LINE = 6;mRecyclerView = (RecyclerView) root.findViewById(R.id.rv);mGridLayoutManager = new FocusGridLayoutManager(getContext(), ITEMS_COUNT_ONE_LINE);mGridLayoutManager.setOrientation(RecyclerView.VERTICAL);mRecyclerView.setLayoutManager(mGridLayoutManager);

解决此问题的核心是修改 FocusGridLayoutManager

public class FocusGridLayoutManager extends android.support.v7.widget.GridLayoutManager {}

在此GridlayoutManager中，重载方法onInterceptFocusSearch

@Override    public View onInterceptFocusSearch(View focused, int direction) {        if (direction == View.FOCUS_DOWN) {            int pos = getPosition(focused);            int nextPos = getNextViewPos(pos, direction);            int size = getChildCount();            int count = getItemCount();            if (size > 0) {                int startIndex = 0;                if (size >= mSpanCount) {                    startIndex = size - mSpanCount;                }                View view;                for (int i = startIndex; i < size; i++) {                    view = getChildAt(i);                    if (view == focused) {                        int lastVisibleItemPos = findLastCompletelyVisibleItemPosition();                        if (pos > lastVisibleItemPos) { //lastVisibleItemPos==-1 ||                            return focused;                        } else {                            int lastLineStartIndex = 0;                            if (count >= mSpanCount) {                                lastLineStartIndex = count - mSpanCount;                            }                            if (pos >= lastLineStartIndex && pos < count) { //最后一排的可见view时,返回当前view                                return focused;                            }                            break;                        }                    }                }            } else {                return focused;            }        }        return super .onInterceptFocusSearch(focused, direction);    }

最核心的是两个地方

1.if (pos > lastVisibleItemPos) 若当前要显示的位置，大于可见的Item的位置，即此时，有可能焦点会乱跑了，此时，返回当前的View作为下一个要Focus的View.

2.if (pos >= lastLineStartIndex && pos < count) 最后一排的可见view时,返回当前view，避免会加载看不见的view,此时也会乱跑。

至此，解决了乱跑问题。其他类型的LayoutManager也可照此方法解决。

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