linearlayoutmanager固定高度

//targetNum 指定数量
mRecyclerview.setLayoutManager(new LinearLayoutManager(getContext()) {
@Override
public void onMeasure(RecyclerView.Recycler recycler, RecyclerView.State state, int widthSpec, int heightSpec) {
int count = state.getItemCount();
if (count > 0) {
if (count > targetNum) {
count = targetNum;
}
int realHeight = 0;
int realWidth = 0;
for (int i = 0; i < count; i++) {
View view = recycler.getViewForPosition(0);
if (view != null) {
measureChild(view, widthSpec, heightSpec);
int measuredWidth = View.MeasureSpec.getSize(widthSpec);
int measuredHeight = view.getMeasuredHeight();
realWidth = realWidth > measuredWidth ? realWidth : measuredWidth;
realHeight = realHeight + measuredHeight;
}
}
setMeasuredDimension(realWidth, realHeight);
} else {
super.onMeasure(recycler, state, widthSpec, heightSpec);
}
}
});