如何在BottomSheetDialog android的顶部中心添加关闭按钮？

我已经通过使用带有自定义（底部）动画的Dialog（全屏）解决了这个问题。

设计：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@color/colorTransparent"
android:orientation="vertical"
>
<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:gravity="center"
    >
    <ImageView
        android:id="@+id/img_close"
        android:layout_width="@dimen/fifty_dp"
        android:layout_height="@dimen/thirty_dp"
        android:src="@drawable/ic_close_filter"/>
</LinearLayout>
<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="@color/white"
    android:orientation="vertical">


<!-- All your required widgets here-->
    </LinearLayout> </LinearLayout>

Java代码：

  Dialog filterDialog;
    AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());

    // Get the layout inflater
    LayoutInflater inflater = getActivity().getLayoutInflater();
    View rootView = inflater.inflate(R.layout.dialog_filter, null);

    final ImageView close = (ImageView) rootView.findViewById(R.id.img_close);

    builder.setView(rootView);

    filterDialog = builder.create();

    WindowManager.LayoutParams lp2 = new WindowManager.LayoutParams();
    Window window = filterDialog.getWindow();
    filterDialog.getWindow().setBackgroundDrawable(new ColorDrawable(android.graphics.Color.TRANSPARENT));
    lp2.copyFrom(window.getAttributes());
    //This makes the dialog take up the full width
    lp2.width = ViewGroup.LayoutParams.MATCH_PARENT;
    lp2.height = ViewGroup.LayoutParams.WRAP_CONTENT;
    window.setAttributes(lp2);
    Window dialogWindow = filterDialog.getWindow();
    WindowManager.LayoutParams lp = dialogWindow.getAttributes();
    dialogWindow.setGravity(Gravity.BOTTOM );

    filterDialog.getWindow().setWindowAnimations(R.style.CustomDialogAnimation);
    filterDialog.show();