对于这个问题，有一个非常简单而灵活的解决方案，它只使用适用于每个LayoutManager的XML。

假设你想要一个相等的X间距(例如8dp)。

在另一个布局中包装CardView项 给外层布局填充X/2 (4dp) 使外层布局背景透明

...

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="200dp"
    android:layout_height="200dp"
    android:background="@android:color/transparent"
    android:padding="4dip">

    <android.support.v7.widget.CardView
        android:layout_width="match_parent"
        android:layout_height="match_parent">
    </android.support.v7.widget.CardView>

</LinearLayout>

给你的RecyclerView填充X/2 (4dp)

...

<android.support.v7.widget.RecyclerView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="4dp" />

就是这样。你有完美的X (8dp)间距。

如果你有一个在列表和网格之间切换的拨动开关，不要忘记在设置任何新的项目装饰之前调用recyclerView.removeItemDecoration(..)。如果不是这样，那么新的间隔计算将是不正确的。

就像这样:

recyclerView.removeItemDecoration(gridItemDecorator)
recyclerView.removeItemDecoration(listItemDecorator)

if (showAsList) {
    recyclerView.layoutManager = LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false)
    recyclerView.addItemDecoration(listItemDecorator)
} else {
    recyclerView.layoutManager = GridLayoutManager(this, spanCount)
    recyclerView.addItemDecoration(gridItemDecorator)
}

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;
}

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)));

对于StaggeredGridLayoutManager用户，要小心，这里有很多答案，包括投票最多的一个计算项目列，使用以下代码:

int column = position % spanCount

假设第1 /3 /5 /..物品总是放在左边和第二/第四/第六/..物品总是放在右边。这个假设总是正确的吗?不。

假设你的第一件物品是100dp高，第二件只有50dp高，猜猜你的第三件物品位于哪里，左边还是右边?