解決NestedScrollView嵌套RecycleView的bug

正常情況下NestedScrollView嵌套RecycleView，一是會出現只顯示一行的情況，二是滑動異常即事件沖突。

解決方法：

1.也是最簡單的方法，把design庫和V7庫升級到23.2以上，注意加上以下代碼

 mLinearLayoutManager.setSmoothScrollbarEnabled(true);
        mLinearLayoutManager.setAutoMeasureEnabled(true);
        cardslist_view.setLayoutManager(mLinearLayoutManager);
        cardslist_view.setHasFixedSize(true);
        cardslist_view.setNestedScrollingEnabled(false);

2.麻煩一點，重寫LinearLayoutManager和NestedScrollView。

public class CustomLinearLayoutManager extends LinearLayoutManager {

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

    private int[] mMeasuredDimension = new int[2];

    @Override
    public void onMeasure(RecyclerView.Recycler recycler, RecyclerView.State state,
                          int widthSpec, int heightSpec) {
        final int widthMode = View.MeasureSpec.getMode(widthSpec);
        final int heightMode = View.MeasureSpec.getMode(heightSpec);
        final int widthSize = View.MeasureSpec.getSize(widthSpec);
        final int heightSize = View.MeasureSpec.getSize(heightSpec);
        int width = 0;
        int height = 0;
        for (int i = 0; i < getItemCount(); i++) {
            if (getOrientation() == HORIZONTAL) {
                measureScrapChild(recycler, i,
                        View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),
                        heightSpec,
                        mMeasuredDimension);

                width = width + mMeasuredDimension[0];
                if (i == 0) {
                    height = mMeasuredDimension[1];
                }
            } else {
                measureScrapChild(recycler, i,
                        widthSpec,
                        View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED),
                        mMeasuredDimension);
                height = height + mMeasuredDimension[1];
                if (i == 0) {
                    width = mMeasuredDimension[0];
                }
            }
        }
        switch (widthMode) {
            case View.MeasureSpec.EXACTLY:
                width = widthSize;
            case View.MeasureSpec.AT_MOST:
            case View.MeasureSpec.UNSPECIFIED:
        }

        switch (heightMode) {
            case View.MeasureSpec.EXACTLY:
                height = heightSize;
            case View.MeasureSpec.AT_MOST:
            case View.MeasureSpec.UNSPECIFIED:
        }

        setMeasuredDimension(width, height);
    }

    private void measureScrapChild(RecyclerView.Recycler recycler, int position, int widthSpec,
                                   int heightSpec, int[] measuredDimension) {
        View view = recycler.getViewForPosition(position);
        recycler.bindViewToPosition(view, position);
        if (view != null) {
            RecyclerView.LayoutParams p = (RecyclerView.LayoutParams) view.getLayoutParams();
            int childWidthSpec = ViewGroup.getChildMeasureSpec(widthSpec,
                    getPaddingLeft() + getPaddingRight(), p.width);
            int childHeightSpec = ViewGroup.getChildMeasureSpec(heightSpec,
                    getPaddingTop() + getPaddingBottom(), p.height);
            view.measure(childWidthSpec, childHeightSpec);
            measuredDimension[0] = view.getMeasuredWidth() + p.leftMargin + p.rightMargin;
            measuredDimension[1] = view.getMeasuredHeight() + p.bottomMargin + p.topMargin;
            recycler.recycleView(view);
        }
    }

}

public class MyNestedScrollView extends NestedScrollView {
    private int downX;
    private int downY;
    private int mTouchSlop;

    public MyNestedScrollView(Context context) {
        super(context);
        mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();
    }

    public MyNestedScrollView(Context context, AttributeSet attrs) {
        super(context, attrs);
        mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();
    }

    public MyNestedScrollView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent e) {
        int action = e.getAction();
        switch (action) {
            case MotionEvent.ACTION_DOWN:
                downX = (int) e.getRawX();
                downY = (int) e.getRawY();
                break;
            case MotionEvent.ACTION_MOVE:
                int moveY = (int) e.getRawY();
                if (Math.abs(moveY - downY) > mTouchSlop) {
                    return true;
                }
        }
        return super.onInterceptTouchEvent(e);
    }
}