这是我对SpacesItemDecoration的修改，它可以在顶部，底部，左边和右边同样采取numofcolumns和空间。

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

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

    @Override
    public void getItemOffsets(Rect outRect, View view,
                               RecyclerView parent, RecyclerView.State state) {

        //outRect.right = space;
        outRect.bottom = space;
        //outRect.left = space;

        //Log.d("ttt", "item position" + parent.getChildLayoutPosition(view));
        int position=parent.getChildLayoutPosition(view);

        if(mNumCol<=2) {
            if (position == 0) {
                outRect.left = space;
                outRect.right = space / 2;
            } else {
                if ((position % mNumCol) != 0) {
                    outRect.left = space / 2;
                    outRect.right = space;
                } else {
                    outRect.left = space;
                    outRect.right = space / 2;
                }
            }
        }else{
            if (position == 0) {
                outRect.left = space;
                outRect.right = space / 2;
            } else {
                if ((position % mNumCol) == 0) {
                    outRect.left = space;
                    outRect.right = space/2;
                } else if((position % mNumCol) == (mNumCol-1)){
                    outRect.left = space/2;
                    outRect.right = space;
                }else{
                    outRect.left=space/2;
                    outRect.right=space/2;
                }
            }

        }

        if(position<mNumCol){
            outRect.top=space;
        }else{
            outRect.top=0;
        }
        // Add top margin only for the first item to avoid double space between items
        /*
        if (parent.getChildLayoutPosition(view) == 0 ) {

        } else {
            outRect.top = 0;
        }*/
    }
}

并在逻辑上使用下面的代码。

recyclerView.addItemDecoration(new SpacesItemDecoration(spacingInPixels, numCol));

public class GridSpacingItemDecoration extends RecyclerView.ItemDecoration {

    private int spanCount;
    private int spacing;
    private boolean includeEdge;

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

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        StaggeredGridLayoutManager.LayoutParams params = (StaggeredGridLayoutManager.LayoutParams) view.getLayoutParams();
        int column = params.getSpanIndex();

        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
            }
        }
    }
}

与edwardaa的回答略有不同，不同之处在于列是如何确定的，因为在一些情况下，例如具有不同高度的项目，列不能简单地通过% spanCount确定

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">

这是我在Kotlin中编写的更灵活的版本，您可以在dp中设置参数。

class ItemDividerGrid(private val numberOfColumns: Int, private val rowSpacingDP: Float = 0f, private val columnSpacingDP: Float = 0f, private val edgeSpacingVerticalDP: Float = 0f, private val edgeSpacingHorizontalDP: Float = 0f) : ItemDecoration() {

    override fun getItemOffsets(outRect: Rect, view: View, parent: RecyclerView, state: RecyclerView.State) {
        val position = parent.getChildAdapterPosition(view)
        val numberOfRows = (parent.adapter?.itemCount?:-1)/numberOfColumns
        val column = position % numberOfColumns
        val row = position / numberOfColumns
        val context = view.context
        ///horizontal
        when(column){
            0 -> {
                outRect.left = convertDpToPixel(edgeSpacingVerticalDP,context)
                outRect.right = convertDpToPixel(columnSpacingDP/2, context)
            }
            numberOfColumns-1 -> {
                outRect.left = convertDpToPixel(columnSpacingDP/2, context)
                outRect.right = convertDpToPixel(edgeSpacingVerticalDP, context)
            }
            else -> {
                outRect.left = convertDpToPixel(columnSpacingDP/2, context)
                outRect.right = convertDpToPixel(columnSpacingDP/2, context)
            }
        }
        //vertical
        when(row){
            0  -> {
                outRect.top = convertDpToPixel(edgeSpacingHorizontalDP,context)
                outRect.bottom = convertDpToPixel(rowSpacingDP/2, context)
            }
            numberOfRows -> {
                outRect.top = convertDpToPixel(rowSpacingDP/2, context)
                outRect.bottom = convertDpToPixel(edgeSpacingHorizontalDP, context)
            }
            else -> {
                outRect.top = convertDpToPixel(rowSpacingDP/2, context)
                outRect.bottom = convertDpToPixel(rowSpacingDP/2, context)
            }
        }
    }
    fun convertDpToPixel(dp: Float, context: Context?): Int {
        return if (context != null) {
            val resources = context.resources
            val metrics = resources.displayMetrics
            (dp * (metrics.densityDpi.toFloat() / DisplayMetrics.DENSITY_DEFAULT)).roundToInt()
        } else {
            val metrics = Resources.getSystem().displayMetrics
            (dp * (metrics.densityDpi.toFloat() / DisplayMetrics.DENSITY_DEFAULT)).roundToInt()
        }
    }
}

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)));

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));