Android BottomSheet实现可拉伸控件

implementation 'com.android.support:design:28.0.0'

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:app="http://schemas.android.com/apk/res-auto"
  xmlns:tools="http://schemas.android.com/tools"
  android:orientation="vertical"
  android:layout_width="match_parent"
  android:layout_height="match_parent">
 
  <com.amap.api.maps.MapView
    android:id="@+id/map"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    />
  <RelativeLayout
    android:id="@+id/bottom_sheet"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginBottom="@dimen/height52px"
    app:behavior_hideable="false"
    app:behavior_peekHeight="@dimen/height84px"
    app:layout_behavior="android.support.design.widget.BottomSheetBehavior"
    tools:ignore="MissingPrefix"
    android:background="#ffffffff"
    >
 
    <include layout="@layout/bottom_sheet" />
  </RelativeLayout>
 
</android.support.design.widget.CoordinatorLayout>
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:layout_height="@dimen/height216px"
  >
  <TextView
    android:layout_width="match_parent"
    android:layout_height="100dp"
    android:gravity="center"
    android:text="bottom_sheet_peek" />
</RelativeLayout>

//底部抽屉栏展示地址
    mBehavior = BottomSheetBehavior.from(mRelativeLayout);
 
    mBehavior.setBottomSheetCallback(new BottomSheetBehavior.BottomSheetCallback() {
      @Override
      public void onStateChanged(@NonNull View bottomSheet, @BottomSheetBehavior.State int newState) {
        String state = "null";
        switch (newState) {
          case 1:
            state = "STATE_DRAGGING";//过渡状态此时用户正在向上或者向下拖动bottom sheet
            break;
          case 2:
            state = "STATE_SETTLING"; // 视图从脱离手指自由滑动到最终停下的这一小段时间
            break;
          case 3:
            state = "STATE_EXPANDED"; //处于完全展开的状态
 
            break;
          case 4:
            state = "STATE_COLLAPSED"; //默认的折叠状态
            break;
          case 5:
            state = "STATE_HIDDEN"; //下滑动完全隐藏 bottom sheet
            break;
        }
 
      }
 
      @Override
      public void onSlide(@NonNull View bottomSheet, float slideOffset) {
        Log.i("BottomSheetDemo", "slideOffset:" + slideOffset);
      }
    });

// behavior_hideable：定义是否能通过下滑手势收起Bottom Sheet。
   app:behavior_hideable="true"
  //  behavior_peekHeight：定义可见部分的高度。
  app:behavior_peekHeight="80dp"
  app:layout_behavior="android.support.design.widget.BottomSheetBehavior"