public class SpacesItemDecoration extends RecyclerView.ItemDecoration {
    private int space;

    public SpacesItemDecoration(int space) {
        this.space = space;
    }

    @Override
    public void getItemOffsets(Rect outRect, View view,
                               RecyclerView parent, RecyclerView.State state) {
        outRect.left = space;
        outRect.right = space;
        outRect.bottom = space;

        // Add top margin only for the first item to avoid double space between items
        if (parent.getChildPosition(view) == 0)
            outRect.top = space;
    }
}

设置item间距

int space = 8;
mRecyclerView.addItemDecoration(new SpacesItemDecoration(spacingInPixels));

这里是GridLayoutManager或者StaggeredGridLayoutManager 设置Item间距的办法

public class SpaceItemDecoration extends RecyclerView.ItemDecoration {
    int mSpace;

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        super.getItemOffsets(outRect, view, parent, state);
        outRect.left = mSpace;
        outRect.right = mSpace;
        outRect.bottom = mSpace;
        if (parent.getChildAdapterPosition(view) == 0) {
            outRect.top = mSpace * 2;
        }

    }

    public SpaceItemDecoration(int space) {
        this.mSpace = space;
    }
}

articleRV = (RecyclerView) mRootView.findViewById(R.id.rv_article);
articleRV.addItemDecoration(new SpaceItemDecoration(30));