[移动开发]＜android＞RecyclerView使用GridLayoutManager间距均分问题，别再修改xml了

/**
 * recyclerview设置GridLayoutManager 等分margin宽度时的自定义ItemDecoration
 */
public class RecyclerViewMarginDecoration extends RecyclerView.ItemDecoration {

private int mMargin;
int spanCount;

    /**
     * @param context   上下文
     * @param spanCount 每行的item数量
     * @param margin    均宽的magin值
     */
public RecyclerViewMarginDecoration(Context context, int spanCount, int margin) {
        mMargin = ScreenUtil.dpAdapt((Activity) context, margin, 375);
        this.spanCount = spanCount;
    }

    @Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        RecyclerView.LayoutManager manager = parent.getLayoutManager();
        if (manager instanceof GridLayoutManager) {
            final GridLayoutManager gridManager = ((GridLayoutManager) manager);
            GridLayoutManager.SpanSizeLookup spanSizeLookup = gridManager.getSpanSizeLookup();
            int spanSize = spanSizeLookup.getSpanSize(parent.getChildAdapterPosition(view));
            if (spanSize == 1) {
                if (parent.getChildLayoutPosition(view) % spanCount == 0) {
                    outRect.set(mMargin, 0, mMargin / 2, 0);
                } else {
                    int lineNumber = (parent.getChildLayoutPosition(view) / spanCount) + 1;//找到行数
                    int lastItem = lineNumber * spanCount - 1; //找到这一行的最后一个item位置
                    if (parent.getChildLayoutPosition(view) == lastItem) {
                        outRect.set(mMargin / 2, 0, mMargin, 0);
                    } else {
                        outRect.set(mMargin / 2, 0, mMargin / 2, 0);
                    }
                }
            }
        }
    }
}

使用：

recyclerview.addItemDecoration(new RecyclerViewMarginDecoration(this,2,15));