默认BottomSheetDialogFragment 菜单全部显示

import android.support.annotation.Nullable;
import android.support.design.widget.BottomSheetDialogFragment;
import android.support.design.widget.BottomSheetBehavior;
import android.support.design.widget.CoordinatorLayout;

@Override
public void onStart() {
  super.onStart();
  final View view = getView();
  view.post(new Runnable() {
    @Override
    public void run() {
      View parent = (View) view.getParent();
      CoordinatorLayout.LayoutParams params = (CoordinatorLayout.LayoutParams) (parent).getLayoutParams();
      CoordinatorLayout.Behavior behavior = params.getBehavior();
      mBehavior = (BottomSheetBehavior) behavior;
      mBehavior.setState(BottomSheetBehavior.STATE_EXPANDED);
    }
  });
}