效果图：

使用方法：

添加默认分割线：高度为2px，颜色为灰色

mRecyclerView.addItemDecoration(new RecycleViewDivider(mContext, LinearLayoutManager.VERTICAL));

添加自定义分割线：可自定义分割线drawable

mRecyclerView.addItemDecoration(new RecycleViewDivider(      mContext, LinearLayoutManager.VERTICAL, R.drawable.divider_mileage));

添加自定义分割线：可自定义分割线高度和颜色

mRecyclerView.addItemDecoration(new RecycleViewDivider(      mContext, LinearLayoutManager.VERTICAL, 10, getResources().getColor(R.color.divide_gray_color)));

万能分割线登场：

public class RecycleViewDivider extends RecyclerView.ItemDecoration {        private Paint mPaint;      private Drawable mDivider;      private int mDividerHeight = 2;//分割线高度，默认为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};        /** * 默认分割线：高度为2px，颜色为灰色 * * @param context * @param orientation 列表方向 */      public RecycleViewDivider(Context context, int orientation) {          if (orientation != LinearLayoutManager.VERTICAL && orientation != LinearLayoutManager.HORIZONTAL) {              throw new IllegalArgumentException("请输入正确的参数！");          }          mOrientation = orientation;            final TypedArray a = context.obtainStyledAttributes(ATTRS);          mDivider = a.getDrawable(0);          a.recycle();      }        /** * 自定义分割线 * * @param context * @param orientation 列表方向 * @param drawableId 分割线图片 */      public RecycleViewDivider(Context context, int orientation, int drawableId) {          this(context, orientation);          mDivider = ContextCompat.getDrawable(context, drawableId);          mDividerHeight = mDivider.getIntrinsicHeight();      }        /** * 自定义分割线 * * @param context * @param orientation 列表方向 * @param dividerHeight 分割线高度 * @param dividerColor 分割线颜色 */      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);      }          //获取分割线尺寸      @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);      }        //绘制分割线      @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);          }      }        //绘制横向 item 分割线      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);              }          }      }        //绘制纵向 item 分割线      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);              }          }      }  }

附：自定的drawable文件一份

<?xml version="1.0" encoding="utf-8"?>  <shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle">      <size android:height="20dp" />      <solid android:color="#ff992900" />  </shape>