Cacher is the code snippet organizer for pro developers

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="185dp"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    android:background="@color/transparent"
    android:padding="10dp">

    <RelativeLayout
        android:layout_width="165dp"
        android:layout_height="280dp"
        android:background="@color/white"
        android:orientation="vertical">
  </RelativeLayout>
</LinearLayout>

比如在这个Item，外面包一层透明的LinearLayout，通过padding和margin来控制间距

public class GridSpacingItemDecoration extends RecyclerView.ItemDecoration {

   private int spanCount; //列数
   private int spacing; //间隔
   private boolean includeEdge; //是否包含边缘

    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) {

       //这里是关键，需要根据你有几列来判断
        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
            }
        }
    }
}
调用的地方

        int spanCount = 3; // 3 columns
        int spacing = 50; // 50px
        boolean includeEdge = false;
        mRecyclerView.addItemDecoration(new GridSpacingItemDecoration(spanCount, spacing, includeEdge));

这是LinearLayoutManager设置Item间距的的一个辅助类

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));