老早之前做的一个功能，横向recyclerview滑动时，底部做跟随滑动指示器。今天代码不用了，记录下代码。

<LinearLayoutandroid:layout_width="match_parent"android:layout_height="wrap_content"android:layout_marginTop="@dimen/fourteen"android:orientation="vertical"android:paddingLeft="@dimen/sixteen"android:paddingRight="@dimen/sixteen"><androidx.recyclerview.widget.RecyclerViewandroid:id="@+id/rv_teacher"android:layout_width="match_parent"android:layout_height="wrap_content"></androidx.recyclerview.widget.RecyclerView><RelativeLayoutandroid:id="@+id/scroll_bar_bg"android:layout_width="30dp"android:layout_height="4dp"android:layout_gravity="center"android:layout_marginTop="@dimen/six"android:background="@drawable/bg_fast_view"><Viewandroid:id="@+id/scroll_bar"android:layout_width="20dp"android:layout_height="4dp"android:layout_centerVertical="true"android:background="@drawable/bg_scroll_bar" /></RelativeLayout></LinearLayout>

bg_fast_view

<shape xmlns:android="http://schemas.android.com/apk/res/android"><solidandroid:color="@color/Gray"/><cornersandroid:radius="@dimen/ten"/></shape>

bg_scroll_bar

<shape xmlns:android="http://schemas.android.com/apk/res/android"><solidandroid:color="@color/title_bg"/><cornersandroid:radius="@dimen/ten"/></shape>

RelativeLayout scrollBarBg = view.findViewById(R.id.parent_layout);
View scrollBar = view.findViewById(R.id.main_line);GridLayoutManager layoutManager = new GridLayoutManager(mContext, 2);layoutManager.setOrientation(LinearLayoutManager.HORIZONTAL);rvTeacher.setLayoutManager(layoutManager);teacherAdapter = new RecommendTeacherRVAdapter(mContext);rvTeacher.setAdapter(teacherAdapter);rvTeacher.addOnScrollListener(new RecyclerView.OnScrollListener() {public int range = 0;@Overridepublic void onScrollStateChanged(RecyclerView recyclerView, int newState) {super.onScrollStateChanged(recyclerView, newState);}@Overridepublic void onScrolled(RecyclerView recyclerView, int dx, int dy) {super.onScrolled(recyclerView, dx, dy);//整体的总宽度，注意是整体，包括在显示区域之外的。int temp = recyclerView.computeHorizontalScrollRange();if (temp > range) {range = temp;}int offset = recyclerView.computeHorizontalScrollOffset();int extent = recyclerView.computeHorizontalScrollExtent();float proportion = (float) (offset * 1.0 / (range - extent));//计算滚动条宽度float transMaxRange = scrollBarBg.getWidth() - scrollBar.getWidth();//设置滚动条移动scrollBar.setTranslationX(transMaxRange * proportion);}});