已记录

public class RecyclerViewSpacesItemDecoration extends RecyclerView.ItemDecoration {
 
   private HashMap<String, Integer> mSpaceValueMap;
 
   public static final String TOP_DECORATION = "top_decoration";
   public static final String BOTTOM_DECORATION = "bottom_decoration";
   public static final String LEFT_DECORATION = "left_decoration";
   public static final String RIGHT_DECORATION = "right_decoration";
​
   public RecyclerViewSpacesItemDecoration(HashMap<String, Integer> mSpaceValueMap) {
       this.mSpaceValueMap = mSpaceValueMap;
   }
​
   @Override
   public void getItemOffsets(Rect outRect, View view,
                               RecyclerView parent, RecyclerView.State state) {
       if (mSpaceValueMap.get(TOP_DECORATION) != null)
           outRect.top = mSpaceValueMap.get(TOP_DECORATION);
       if (mSpaceValueMap.get(LEFT_DECORATION) != null)
           outRect.left = mSpaceValueMap.get(LEFT_DECORATION);
       if (mSpaceValueMap.get(RIGHT_DECORATION) != null)
           outRect.right = mSpaceValueMap.get(RIGHT_DECORATION);
       if (mSpaceValueMap.get(BOTTOM_DECORATION) != null)
           outRect.bottom = mSpaceValueMap.get(BOTTOM_DECORATION);
   }
}

调用即可

HashMap<String, Integer> stringIntegerHashMap = new HashMap<>();
stringIntegerHashMap.put(RecyclerViewSpacesItemDecoration.TOP_DECORATION,50);//top间距
 
stringIntegerHashMap.put(RecyclerViewSpacesItemDecoration.BOTTOM_DECORATION,100);//底部间距
 
stringIntegerHashMap.put(RecyclerViewSpacesItemDecoration.LEFT_DECORATION,50);//左间距
 
stringIntegerHashMap.put(RecyclerViewSpacesItemDecoration.RIGHT_DECORATION,100);//右间距
 
mRecyclerView.addItemDecoration(newRecyclerViewSpacesItemDecoration(stringIntegerHashMap));

参考文章：

https://blog.csdn.net/yangbin0513/article/details/71515893