RecycleView沒(méi)有設(shè)置分割線的方法。有兩種方法可以實(shí)現(xiàn)分割線。一種方法是在Item中設(shè)置一個(gè)分割線（用過(guò)這個(gè)方法，這種方法實(shí)際上是非常麻煩的）。
另外是自定一個(gè)分割線（本文主要講的）。
我實(shí)現(xiàn)這個(gè)效果之后找到一篇非常不錯(cuò)的博客：http://blog.csdn.net/pengkv/article/details/50538121
博客封裝得不錯(cuò)，比自己寫(xiě)的半吊子要好，所以直接拿來(lái)使用并封裝在了開(kāi)發(fā)框架內(nèi)。
使用方法
提供了三個(gè)構(gòu)造函數(shù)，使用者可以使用默認(rèn)的或者自定義樣式。

//添加默認(rèn)分割線：高度為2px，顏色為灰色
mRecyclerView.addItemDecoration(new RecycleViewDivider(mContext, LinearLayoutManager.VERTICAL));

//添加自定義分割線：可自定義分割線drawable
mRecyclerView.addItemDecoration(new RecycleViewDivider(
    mContext, LinearLayoutManager.VERTICAL, R.drawable.divider_mileage));

//添加自定義分割線：可自定義分割線高度和顏色
mRecyclerView.addItemDecoration(new RecycleViewDivider(
    mContext, LinearLayoutManager.VERTICAL, 10, getResources().getColor(R.color.divide_gray_color)));

萬(wàn)能分割線類
非常通用的類，可以根據(jù)自定項(xiàng)目中的需求修改樣式。
不過(guò)這個(gè)源碼是有個(gè)坑的，就是構(gòu)造函數(shù)里面的this(context, orientation);使用的時(shí)候一定要注釋或者刪除。否則都是默認(rèn)的效果！

public class RecycleViewDivider extends RecyclerView.ItemDecoration {

    private Paint mPaint;
    private Drawable mDivider;
    private int mDividerHeight = 2;//分割線高度，默認(rèn)為1px
    private int mOrientation;//列表的方向：LinearLayoutManager.VERTICAL或LinearLayoutManager.HORIZONTAL
    private static final int[] ATTRS = new int[]{android.R.attr.listDivider};

    /**
     * 默認(rèn)分割線：高度為2px，顏色為灰色
     *
     * @param context
     * @param orientation 列表方向
     */
    public RecycleViewDivider(Context context, int orientation) {
        if (orientation != LinearLayoutManager.VERTICAL && orientation != LinearLayoutManager.HORIZONTAL) {
            throw new IllegalArgumentException("請(qǐng)輸入正確的參數(shù)！");
        }
        mOrientation = orientation;

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

    /**
     * 自定義分割線
     *
     * @param context
     * @param orientation 列表方向
     * @param drawableId  分割線圖片
     */
    public RecycleViewDivider(Context context, int orientation, int drawableId) {
        //this(context, orientation);
        mDivider = ContextCompat.getDrawable(context, drawableId);
        mDividerHeight = mDivider.getIntrinsicHeight();
    }

    /**
     * 自定義分割線
     *
     * @param context
     * @param orientation   列表方向
     * @param dividerHeight 分割線高度
     * @param dividerColor  分割線顏色
     */
    public RecycleViewDivider(Context context, int orientation, int dividerHeight, int dividerColor) {
        //this(context, orientation);
        mDividerHeight = dividerHeight;
        mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        mPaint.setColor(dividerColor);
        mPaint.setStyle(Paint.Style.FILL);
    }


    //獲取分割線尺寸
    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        super.getItemOffsets(outRect, view, parent, state);
        outRect.set(0, 0, 0, mDividerHeight);
    }

    //繪制分割線
    @Override
    public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
        super.onDraw(c, parent, state);
        if (mOrientation == LinearLayoutManager.VERTICAL) {
            drawVertical(c, parent);
        } else {
            drawHorizontal(c, parent);
        }
    }

    //繪制橫向 item 分割線
    private void drawHorizontal(Canvas canvas, RecyclerView parent) {
        final int left = parent.getPaddingLeft();
        final int right = parent.getMeasuredWidth() - parent.getPaddingRight();
        final int childSize = parent.getChildCount();
        for (int i = 0; i < childSize; i++) {
            final View child = parent.getChildAt(i);
            RecyclerView.LayoutParams layoutParams = (RecyclerView.LayoutParams) child.getLayoutParams();
            final int top = child.getBottom() + layoutParams.bottomMargin;
            final int bottom = top + mDividerHeight;
            if (mDivider != null) {
                mDivider.setBounds(left, top, right, bottom);
                mDivider.draw(canvas);
            }
            if (mPaint != null) {
                canvas.drawRect(left, top, right, bottom, mPaint);
            }
        }
    }

    //繪制縱向 item 分割線
    private void drawVertical(Canvas canvas, RecyclerView parent) {
        final int top = parent.getPaddingTop();
        final int bottom = parent.getMeasuredHeight() - parent.getPaddingBottom();
        final int childSize = parent.getChildCount();
        for (int i = 0; i < childSize; i++) {
            final View child = parent.getChildAt(i);
            RecyclerView.LayoutParams layoutParams = (RecyclerView.LayoutParams) child.getLayoutParams();
            final int left = child.getRight() + layoutParams.rightMargin;
            final int right = left + mDividerHeight;
            if (mDivider != null) {
                mDivider.setBounds(left, top, right, bottom);
                mDivider.draw(canvas);
            }
            if (mPaint != null) {
                canvas.drawRect(left, top, right, bottom, mPaint);
            }
        }
    }
}

原文來(lái)自：http://blog.csdn.net/pengkv/article/details/50538121
向開(kāi)源者致敬！