早上來到公司，開啟部落格，看到一篇部落格 http://blog.csdn.net/laoyang360/article/details/53843771  三執行緒序員的年中告白 我有感而發，為什麼呢？沒錯 ，我不是三線的，我是四線城市的，現在的我每天早上8點上班 晚上5.30下班，在入職半個月以來，每天基本上都是一些小的問題，所以打算以後一週寫一篇部落格，來記錄自己平時學習的積累，以後希望大家一起進步 幾年之後一起見證我們程式設計師之路的成長，也希望大神們多多指教，幾年之後希望我還在堅持寫部落格，忙的時候可能會沒時間寫部落格，但我不會忘記這件事情的。大家一起監督。  下面內容是之前寫recyclerview 寫網格佈局要用到分割線的時候在網上找到的一個類 和大家分享一下，很好用。

public class DividerGridItemDecoration extends RecyclerView.ItemDecoration {

    private static final int[] ATTRS = new int[]{android.R.attr.listDivider};
    private Drawable mDivider;

    public DividerGridItemDecoration(Context context) {
        final TypedArray a = context.obtainStyledAttributes(ATTRS
 
);
        mDivider = a.getDrawable(0);
        a.recycle();
    }

    @Override
public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {//這個時候垂直和水平方向都需要重新繪製
drawHorizontal(c, parent);
        drawVertical(c, parent);
    }

    private int getSpanCount(RecyclerView parent) {
        // 列數
 
int spanCount = -1;
        RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();
        if (layoutManager instanceof GridLayoutManager) {
            spanCount = ((GridLayoutManager) layoutManager).getSpanCount();
        } else if (layoutManager instanceof StaggeredGridLayoutManager)

        {
            spanCount = ((StaggeredGridLayoutManager) layoutManager).getSpanCount();
        }
        return spanCount;
    }

    public void drawHorizontal(Canvas c, RecyclerView parent) {
        int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = parent.getChildAt(i);
            final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
                    .getLayoutParams();
            final int left = child.getLeft() - params.leftMargin;
            final int right = child.getRight() + params.rightMargin
+ mDivider.getIntrinsicWidth();
            final int top = child.getBottom() + params.bottomMargin;
            final int bottom = top + mDivider.getIntrinsicHeight();
            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(c);
        }
    }

    public void drawVertical(Canvas c, RecyclerView parent) {
        final int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = parent.getChildAt(i);

            final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
                    .getLayoutParams();
            final int top = child.getTop() - params.topMargin;
            final int bottom = child.getBottom() + params.bottomMargin;
            final int left = child.getRight() + params.rightMargin;
            final int right = left + mDivider.getIntrinsicWidth();

            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(c);
        }
    }

    /**
     * 74.     * 判斷是否是最後一列
     * 75.
     */
private boolean isLastColum(RecyclerView parent, int pos, int spanCount, int childCount) {
        RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();
        if (layoutManager instanceof GridLayoutManager) {
            if ((pos + 1) % spanCount == 0)// 如果是最後一列，則不需要繪製右邊
{
                return true;
            }
        } else if (layoutManager instanceof StaggeredGridLayoutManager) {
            int orientation = ((StaggeredGridLayoutManager) layoutManager)
                    .getOrientation();
            if (orientation == StaggeredGridLayoutManager.VERTICAL) {
                if ((pos + 1) % spanCount == 0)// 如果是最後一列，則不需要繪製右邊
{
                    return true;
                }
            } else {
                childCount = childCount - childCount % spanCount;
                if (pos >= childCount)// 如果是最後一列，則不需要繪製右邊
return true;
            }
        }
        return false;
    }

    /**
     * 106.     * 是否是最後一行
     * 107.
     */
private boolean isLastRaw(RecyclerView parent, int pos, int spanCount, int childCount) {
        RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();
        if (layoutManager instanceof GridLayoutManager) {
            childCount = childCount - childCount % spanCount;
            if (pos >= childCount)// 如果是最後一行，則不需要繪製底部
return true;
        } else if (layoutManager instanceof StaggeredGridLayoutManager) {
            int orientation = ((StaggeredGridLayoutManager) layoutManager)
                    .getOrientation();
            // StaggeredGridLayoutManager 且縱向滾動
if (orientation == StaggeredGridLayoutManager.VERTICAL) {
                childCount = childCount - childCount % spanCount;
                // 如果是最後一行，則不需要繪製底部
if (pos >= childCount)
                    return true;
            } else
// StaggeredGridLayoutManager 且橫向滾動
{
                // 如果是最後一行，則不需要繪製底部
if ((pos + 1) % spanCount == 0) {
                    return true;
                }
            }
        }
        return false;
    }

    @Override
public void getItemOffsets(Rect outRect, int itemPosition,
                               RecyclerView parent) {
        int spanCount = getSpanCount(parent);
        int childCount = parent.getAdapter().getItemCount();
        if (isLastRaw(parent, itemPosition, spanCount, childCount))// 如果是最後一行，則不需要繪製底部
{
            outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0);
        } else if (isLastColum(parent, itemPosition, spanCount, childCount))// 如果是最後一列，則不需要繪製右邊
{
            outRect.set(0, 0, 0, mDivider.getIntrinsicHeight());
        } else {
            outRect.set(0, 0, mDivider.getIntrinsicWidth(),
                    mDivider.getIntrinsicHeight());
        }
    }
}

具體用法就是生成一個DividerGridItemDecoration 例項，然後用recycler的addItemDecoration方法，引數就是前面生成的例項。