下面是一个不需要“spanCount”(列数)的解决方案 我使用它是因为我使用GridAutofitLayoutManager(根据所需的单元格大小计算列数)

(注意，这将只工作在GridLayoutManager)

public class GridSpacesItemDecoration extends RecyclerView.ItemDecoration {
    private final boolean includeEdge;
    private int spacing;


    public GridSpacesItemDecoration(int spacing, boolean includeEdge) {
        this.spacing = spacing;
        this.includeEdge = includeEdge;
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        if (parent.getLayoutManager() instanceof GridLayoutManager) {
            GridLayoutManager layoutManager = (GridLayoutManager)parent.getLayoutManager();
            int spanCount = layoutManager.getSpanCount();
            int position = parent.getChildAdapterPosition(view); // item position
            int column = position % spanCount; // item 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
                }
            }

        }

    }
}

这是GridAutofitLayoutManager是谁感兴趣:

public class GridAutofitLayoutManager extends GridLayoutManager {
    private int mColumnWidth;
    private boolean mColumnWidthChanged = true;

    public GridAutofitLayoutManager(Context context, int columnWidth)
    {
        /* Initially set spanCount to 1, will be changed automatically later. */
        super(context, 1);
        setColumnWidth(checkedColumnWidth(context, columnWidth));
    }

    public GridAutofitLayoutManager(Context context,int unit, int columnWidth)
    {
        /* Initially set spanCount to 1, will be changed automatically later. */
        super(context, 1);
        int pixColumnWidth = (int) TypedValue.applyDimension(unit, columnWidth, context.getResources().getDisplayMetrics());
        setColumnWidth(checkedColumnWidth(context, pixColumnWidth));
    }

    public GridAutofitLayoutManager(Context context, int columnWidth, int orientation, boolean reverseLayout)
    {
        /* Initially set spanCount to 1, will be changed automatically later. */
        super(context, 1, orientation, reverseLayout);
        setColumnWidth(checkedColumnWidth(context, columnWidth));
    }

    private int checkedColumnWidth(Context context, int columnWidth)
    {
        if (columnWidth <= 0)
        {
            /* Set default columnWidth value (48dp here). It is better to move this constant
            to static constant on top, but we need context to convert it to dp, so can't really
            do so. */
            columnWidth = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 48,
                    context.getResources().getDisplayMetrics());
        }
        return columnWidth;
    }

    public void setColumnWidth(int newColumnWidth)
    {
        if (newColumnWidth > 0 && newColumnWidth != mColumnWidth)
        {
            mColumnWidth = newColumnWidth;
            mColumnWidthChanged = true;
        }
    }

    @Override
    public void onLayoutChildren(RecyclerView.Recycler recycler, RecyclerView.State state)
    {
        int width = getWidth();
        int height = getHeight();
        if (mColumnWidthChanged && mColumnWidth > 0 && width > 0 && height > 0)
        {
            int totalSpace;
            if (getOrientation() == VERTICAL)
            {
                totalSpace = width - getPaddingRight() - getPaddingLeft();
            }
            else
            {
                totalSpace = height - getPaddingTop() - getPaddingBottom();
            }
            int spanCount = Math.max(1, totalSpace / mColumnWidth);
            setSpanCount(spanCount);

            mColumnWidthChanged = false;
        }
        super.onLayoutChildren(recycler, state);
    }
}

最后:

mDevicePhotosView.setLayoutManager(new GridAutofitLayoutManager(getContext(), getResources().getDimensionPixelSize(R.dimen.item_size)));
mDevicePhotosView.addItemDecoration(new GridSpacesItemDecoration(Util.dpToPx(getContext(), 2),true));

下面是一个不需要“spanCount”(列数)的解决方案 我使用它是因为我使用GridAutofitLayoutManager(根据所需的单元格大小计算列数)

(注意，这将只工作在GridLayoutManager)

public class GridSpacesItemDecoration extends RecyclerView.ItemDecoration {
    private final boolean includeEdge;
    private int spacing;


    public GridSpacesItemDecoration(int spacing, boolean includeEdge) {
        this.spacing = spacing;
        this.includeEdge = includeEdge;
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        if (parent.getLayoutManager() instanceof GridLayoutManager) {
            GridLayoutManager layoutManager = (GridLayoutManager)parent.getLayoutManager();
            int spanCount = layoutManager.getSpanCount();
            int position = parent.getChildAdapterPosition(view); // item position
            int column = position % spanCount; // item 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
                }
            }

        }

    }
}

这是GridAutofitLayoutManager是谁感兴趣:

public class GridAutofitLayoutManager extends GridLayoutManager {
    private int mColumnWidth;
    private boolean mColumnWidthChanged = true;

    public GridAutofitLayoutManager(Context context, int columnWidth)
    {
        /* Initially set spanCount to 1, will be changed automatically later. */
        super(context, 1);
        setColumnWidth(checkedColumnWidth(context, columnWidth));
    }

    public GridAutofitLayoutManager(Context context,int unit, int columnWidth)
    {
        /* Initially set spanCount to 1, will be changed automatically later. */
        super(context, 1);
        int pixColumnWidth = (int) TypedValue.applyDimension(unit, columnWidth, context.getResources().getDisplayMetrics());
        setColumnWidth(checkedColumnWidth(context, pixColumnWidth));
    }

    public GridAutofitLayoutManager(Context context, int columnWidth, int orientation, boolean reverseLayout)
    {
        /* Initially set spanCount to 1, will be changed automatically later. */
        super(context, 1, orientation, reverseLayout);
        setColumnWidth(checkedColumnWidth(context, columnWidth));
    }

    private int checkedColumnWidth(Context context, int columnWidth)
    {
        if (columnWidth <= 0)
        {
            /* Set default columnWidth value (48dp here). It is better to move this constant
            to static constant on top, but we need context to convert it to dp, so can't really
            do so. */
            columnWidth = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 48,
                    context.getResources().getDisplayMetrics());
        }
        return columnWidth;
    }

    public void setColumnWidth(int newColumnWidth)
    {
        if (newColumnWidth > 0 && newColumnWidth != mColumnWidth)
        {
            mColumnWidth = newColumnWidth;
            mColumnWidthChanged = true;
        }
    }

    @Override
    public void onLayoutChildren(RecyclerView.Recycler recycler, RecyclerView.State state)
    {
        int width = getWidth();
        int height = getHeight();
        if (mColumnWidthChanged && mColumnWidth > 0 && width > 0 && height > 0)
        {
            int totalSpace;
            if (getOrientation() == VERTICAL)
            {
                totalSpace = width - getPaddingRight() - getPaddingLeft();
            }
            else
            {
                totalSpace = height - getPaddingTop() - getPaddingBottom();
            }
            int spanCount = Math.max(1, totalSpace / mColumnWidth);
            setSpanCount(spanCount);

            mColumnWidthChanged = false;
        }
        super.onLayoutChildren(recycler, state);
    }
}

最后:

mDevicePhotosView.setLayoutManager(new GridAutofitLayoutManager(getContext(), getResources().getDimensionPixelSize(R.dimen.item_size)));
mDevicePhotosView.addItemDecoration(new GridSpacesItemDecoration(Util.dpToPx(getContext(), 2),true));

对于那些有问题的staggeredLayoutManager(如https://imgur.com/XVutH5u)

recyclerView的方法:

getChildAdapterPosition(view)
getChildLayoutPosition(view)

有时返回-1作为索引，所以我们可能会遇到设置itemDecor的麻烦。我的解决方案是覆盖已弃用的ItemDecoration的方法:

public void getItemOffsets(Rect outRect, int itemPosition, RecyclerView parent)

而不是新手:

public void getItemOffsets(Rect outRect, View view, RecyclerView parent, State state)

是这样的:

recyclerView.addItemDecoration(new RecyclerView.ItemDecoration() {
            @Override
            public void getItemOffsets(Rect outRect, int itemPosition, RecyclerView parent) {
                TheAdapter.VH vh = (TheAdapter.VH) recyclerView.findViewHolderForAdapterPosition(itemPosition);
                View itemView = vh.itemView;    //itemView is the base view of viewHolder
                //or instead of the 2 lines above maybe it's possible to use  View itemView = layoutManager.findViewByPosition(itemPosition)  ... NOT TESTED

                StaggeredGridLayoutManager.LayoutParams itemLayoutParams = (StaggeredGridLayoutManager.LayoutParams) itemView.getLayoutParams();

                int spanIndex = itemLayoutParams.getSpanIndex();

                if (spanIndex == 0)
                    ...
                else
                    ...
            }
        });

到目前为止似乎对我有用:)

当为儿童使用CardView时，项目之间的空格问题可以通过设置app:cardUseCompatPadding为true来解决。

为更大的边际扩大项目抬高。CardElevation是可选的(使用默认值)。

<androidx.cardview.widget.CardView
    xmlns:app="http://schemas.android.com/apk/res-auto"
    app:cardUseCompatPadding="true"
    app:cardElevation="2dp">

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))

Yqritc的回答非常适合我。我用的是Kotlin，这里有一个等价物。

class ItemOffsetDecoration : RecyclerView.ItemDecoration  {

    // amount to add to padding
    private val _itemOffset: Int

    constructor(itemOffset: Int) {
        _itemOffset = itemOffset
    }

    constructor(@NonNull context: Context, @DimenRes itemOffsetId: Int){
       _itemOffset = context.resources.getDimensionPixelSize(itemOffsetId)
    }

    /**
     * Applies padding to all sides of the [Rect], which is the container for the view
     */
    override fun getItemOffsets(outRect: Rect, view: View, parent: RecyclerView,state: RecyclerView.State) {
        super.getItemOffsets(outRect, view, parent, state)
        outRect.set(_itemOffset, _itemOffset, _itemOffset, _itemOffset)
    }
}

其他一切都是一样的。