RecyclerView复用失效场景梳理

讲一下什么情况下RecyclerView回收复用会失效。

整体涉及链路

首先第一层RecyclerView，测量子View的地方，在linearLayoutManager的onLayoutChildren()

public void onLayoutChildren(RecyclerView.Recycler recycler, RecyclerView.State state) {
   
    ...
    mLayoutState.mInfinite = resolveIsInfinite();
    ...
    if (mAnchorInfo.mLayoutFromEnd) {
   
        ...
        fill(recycler, mLayoutState, state, false);
        ...
    }

}
//resolveIsInfinite()开始
boolean resolveIsInfinite() {
   
    return mOrientationHelper.getMode() == View.MeasureSpec.UNSPECIFIED
            && mOrientationHelper.getEnd() == 0;
}


public static OrientationHelper createHorizontalHelper(RecyclerView.LayoutManager layoutManager) {
   
    return new OrientationHelper(layoutManager) {
   
        public int getEndAfterPadding() {
   
            return this.mLayoutManager.getHeight() - this.mLayoutManager.getPaddingBottom();
        }
    
        public int getEnd() {
   
            return this.mLayoutManager.getHeight();
        }        
    }
}
//resolveIsInfinite结束
int fill(RecyclerView.Recycler recycler, LayoutState layoutState,
        RecyclerView.State state, boolean stopOnFocusable) {
   
        ...
        while ((layoutState.mInfinite || remainingSpace > 0) && layoutState.hasMore(state)) {
   
            ...
            layoutChunk(recycler, state, layoutState, layoutChunkResult);
            ...
        }
        ...
        
}

void layoutChunk(RecyclerView.Recycler recycler, RecyclerView.State state,
        LayoutState layoutState, LayoutChunkResult result) {
   
    ...
    measureChildWithMargins(view, 0, 0);
    ....
}

public void measureChildWithMargins(@NonNull View child, int widthUsed, int heightUsed) {
   
    final LayoutParams lp = (LayoutParams) child.getLayoutParams();
    
    final Rect insets = mRecyclerView.getItemDecorInsetsForChild(child);
    widthUsed += insets.left + insets.right;
    heightUsed += insets.top + insets.bottom;
    
    final int widthSpec = getChildMeasureSpec(getWidth(), getWidthMode(),
            getPaddingLeft() + getPaddingRight()
                    + lp.leftMargin + lp.rightMargin + widthUsed, lp.width,
            canScrollHorizontally());
    final int heightSpec = getChildMeasureSpec(getHeight(), getHeightMode(),
            getPaddingTop() + getPaddingBottom()
                    + lp.topMargin + lp.bottomMargin + heightUsed, lp.height,
            canScrollVertically());
    if (shouldMeasureChild(child, widthSpec, heightSpec, lp)) {
   
        child.measure(widthSpec, heightSpec);
    }
}
// 下面这个方法很关键，就不省略了。
public static int getChildMeasureSpec(int parentSize, int parentMode, int padding,
        int childDimension, boolean canScroll) {
   
    int size = Math.max(0, parentSize - padding);
    int resultSize = 0;
    int resultMode = 0;
    if (canScroll) {
   
        if (childDimension >= 0) {
   
            resultSize = childDimension;
            resultMode = MeasureSpec.EXACTLY;
        } else if (childDimension == LayoutParams.MATCH_PARENT) {
   
            switch (parentMode) {
   
                case