复制@edwardaa提供的代码，我使它完美地支持RTL:

public class GridSpacingItemDecoration extends RecyclerView.ItemDecoration {
    private int spanCount;
    private int spacing;
    private boolean includeEdge;
    private int headerNum;
    private boolean isRtl = TextUtilsCompat.getLayoutDirectionFromLocale(Locale.getDefault()) == ViewCompat.LAYOUT_DIRECTION_RTL;

    public GridSpacingItemDecoration(int spanCount, int spacing, boolean includeEdge, int headerNum) {
        this.spanCount = spanCount;
        this.spacing = spacing;
        this.includeEdge = includeEdge;
        this.headerNum = headerNum;
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        int position = parent.getChildAdapterPosition(view) - headerNum; // item position
        if (position >= 0) {
            int column = position % spanCount; // item column
            if(isRtl) {
                column = spanCount - 1 - column;
            }
            if (includeEdge) {
                outRect.left = spacing - column * spacing / spanCount; // spacing - column * ((1f / spanCount) * spacing)
                outRect.right = (column + 1) * spacing / spanCount; // (column + 1) * ((1f / spanCount) * spacing)

                if (position < spanCount) { // top edge
                    outRect.top = spacing;
                }
                outRect.bottom = spacing; // item bottom
            } else {
                outRect.left = column * spacing / spanCount; // column * ((1f / spanCount) * spacing)
                outRect.right = spacing - (column + 1) * spacing / spanCount; // spacing - (column + 1) * ((1f /    spanCount) * spacing)
                if (position >= spanCount) {
                    outRect.top = spacing; // item top
                }
            }
        } else {
            outRect.left = 0;
            outRect.right = 0;
            outRect.top = 0;
            outRect.bottom = 0;
        }
    }
}

如果你使用Header和GridLayoutManager，使用以下代码在Kotlin中编写的网格间距:

inner class SpacesItemDecoration(itemSpace: Int) : RecyclerView.ItemDecoration() {

    var space: Int = itemSpace

    override fun getItemOffsets(outRect: Rect?, view: View?, parent: RecyclerView?, state: RecyclerView.State?) {
        super.getItemOffsets(outRect, view, parent, state)
        val position = parent!!.getChildAdapterPosition(view)
        val viewType = parent.adapter.getItemViewType(position)
        
        // Check to not to set any margin to header item 
        if (viewType == GridViewAdapter.TYPE_HEADER) {
            outRect!!.top = 0
            outRect.left = 0
            outRect.right = 0
            outRect.bottom = 0
        } else {
            outRect!!.left = space
            outRect.right = space
            outRect.bottom = space

            if (parent.getChildLayoutPosition(view) == 0) {
                outRect.top = space
            } else {
                outRect.top = 0
            }
        }
    }
}

并将ItemDecoration传递给RecyclerView为:

gridView.addItemDecoration(SpacesItemDecoration(10))

如果你想在所有设备中固定你的RecyclerView项的大小。你可以这样做

public class GridSpacingItemDecoration extends RecyclerView.ItemDecoration {

    private int mSpanCount;
    private float mItemSize;

    public GridSpacingItemDecoration(int spanCount, int itemSize) {
        this.mSpanCount = spanCount;
        mItemSize = itemSize;
    }

    @Override
    public void getItemOffsets(final Rect outRect, final View view, RecyclerView parent,
            RecyclerView.State state) {
        final int position = parent.getChildLayoutPosition(view);
        final int column = position % mSpanCount;
        final int parentWidth = parent.getWidth();
        int spacing = (int) (parentWidth - (mItemSize * mSpanCount)) / (mSpanCount + 1);
        outRect.left = spacing - column * spacing / mSpanCount;
        outRect.right = (column + 1) * spacing / mSpanCount;

        if (position < mSpanCount) {
            outRect.top = spacing;
        }
        outRect.bottom = spacing;
    }
}

recyclerview_item.xml

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="@dimen/recycler_view_item_width" 
    ...
    >
    ...
</LinearLayout>

dimens.xml

 <dimen name="recycler_view_item_width">60dp</dimen>

活动

int numberOfColumns = 3;
mRecyclerView.setLayoutManager(new GridLayoutManager(this, numberOfColumns));
mRecyclerView.setAdapter(...);
mRecyclerView.addItemDecoration(new GridSpacingItemDecoration(3,
        getResources().getDimensionPixelSize(R.dimen.recycler_view_item_width)));

如果你已经滚动到这个答案，我写了一个等间距库，支持垂直/水平，LTR/RTL，线性布局/GridLayout管理器和边缘包含。它基本上是一个文件，所以你可以复制粘贴该文件到你的代码中。

我试图支持StaggeredGridLayout，但这个布局返回的跨度索引不可靠。我很乐意听到任何有关这方面的建议。

为了使https://stackoverflow.com/a/29905000/1649371(上面)解决方案工作，我必须修改以下方法(以及所有后续调用)

@SuppressWarnings("all")
protected int getItemSpanSize(RecyclerView parent, View view, int childIndex) {

    RecyclerView.LayoutManager mgr = parent.getLayoutManager();
    if (mgr instanceof GridLayoutManager) {
        return ((GridLayoutManager) mgr).getSpanSizeLookup().getSpanSize(childIndex);
    } else if (mgr instanceof StaggeredGridLayoutManager) {
        return ((StaggeredGridLayoutManager.LayoutParams) view.getLayoutParams()).isFullSpan() ? spanCount : 1;
    } else if (mgr instanceof LinearLayoutManager) {
        return 1;
    }

    return -1;
}

@SuppressWarnings("all")
protected int getItemSpanIndex(RecyclerView parent, View view, int childIndex) {

    RecyclerView.LayoutManager mgr = parent.getLayoutManager();
    if (mgr instanceof GridLayoutManager) {
        return ((GridLayoutManager) mgr).getSpanSizeLookup().getSpanIndex(childIndex, spanCount);
    } else if (mgr instanceof StaggeredGridLayoutManager) {
        return ((StaggeredGridLayoutManager.LayoutParams) view.getLayoutParams()).getSpanIndex();
    } else if (mgr instanceof LinearLayoutManager) {
        return 0;
    }

    return -1;
}

选择的答案几乎是完美的，但根据空间的不同，项目的宽度可能不相等。(对我来说，这很关键)。所以我最终用这个代码增加了一点空间，所以项目都是相同的宽度。

   class GridSpacingItemDecoration(private val columnCount: Int, @Px preferredSpace: Int, private val includeEdge: Boolean): RecyclerView.ItemDecoration() {

    /**
     * In this algorithm space should divide by 3 without remnant or width of items can have a difference
     * and we want them to be exactly the same
     */
    private val space = if (preferredSpace % 3 == 0) preferredSpace else (preferredSpace + (3 - preferredSpace % 3))

    override fun getItemOffsets(outRect: Rect, view: View, parent: RecyclerView, state: RecyclerView.State?) {
        val position = parent.getChildAdapterPosition(view)

        if (includeEdge) {

            when {
                position % columnCount == 0 -> {
                    outRect.left = space
                    outRect.right = space / 3
                }
                position % columnCount == columnCount - 1 -> {
                    outRect.right = space
                    outRect.left = space / 3
                }
                else -> {
                    outRect.left = space * 2 / 3
                    outRect.right = space * 2 / 3
                }
            }

            if (position < columnCount) {
                outRect.top = space
            }

            outRect.bottom = space

        } else {

            when {
                position % columnCount == 0 -> outRect.right = space * 2 / 3
                position % columnCount == columnCount - 1 -> outRect.left = space * 2 / 3
                else -> {
                    outRect.left = space / 3
                    outRect.right = space / 3
                }
            }

            if (position >= columnCount) {
                outRect.top = space
            }
        }
    }

}