如何实现Android中BottomSheetDialog的全屏展示效果

默认的BottomSheetDialog受内部BottomSheetBehavior的默认参数限制，展开后最高只能占半屏，按以下步骤修改即可实现全屏效果：

完整修改后的自定义Dialog代码 #

public class BottomSheetDialogBuyPlan extends BottomSheetDialog {
    public BottomSheetDialogBuyPlan(@NonNull Context context) {
        super(context);
        // 提前加载自定义布局
        View bottomSheet = getLayoutInflater().inflate(R.layout.layout, null);
        setContentView(bottomSheet);

        BottomSheetBehavior<FrameLayout> behavior = getBehavior();
        // 设置默认展开状态
        behavior.setState(BottomSheetBehavior.STATE_EXPANDED);
        // 取消默认半高限制，设置收起高度为屏幕完整高度
        DisplayMetrics displayMetrics = context.getResources().getDisplayMetrics();
        behavior.setPeekHeight(displayMetrics.heightPixels);
        // 不需要滑动收起可添加以下代码
        // behavior.setDraggable(false);

        // 修改系统自带BottomSheet容器高度为匹配父布局，避免内部布局被压缩
        FrameLayout bottomSheetContainer = getDelegate().findViewById(com.google.android.material.R.id.design_bottom_sheet);
        if (bottomSheetContainer != null) {
            ViewGroup.LayoutParams layoutParams = bottomSheetContainer.getLayoutParams();
            layoutParams.height = ViewGroup.LayoutParams.MATCH_PARENT;
            bottomSheetContainer.setLayoutParams(layoutParams);
        }

        show();
    }

    @Override
    public void setOnShowListener(@Nullable OnShowListener listener) {
        super.setOnShowListener(listener);
    }
}

可选补充：自定义样式取消默认边距/圆角 #

如果需要去掉弹窗顶部的默认圆角、边距，可在res/values/styles.xml中添加自定义样式：

<style name="FullScreenBottomSheetDialog" parent="Theme.MaterialComponents.Light.BottomSheetDialog">
    <item name="bottomSheetStyle">@style/FullScreenBottomSheetStyle</item>
    <item name="android:statusBarColor">@android:color/transparent</item>
    <item name="android:windowIsFloating">false</item>
</style>

<style name="FullScreenBottomSheetStyle" parent="Widget.MaterialComponents.BottomSheet.Modal">
    <item name="backgroundTint">@android:color/white</item>
    <item name="behavior_peekHeight">match_parent</item>
    <item name="behavior_hideable">true</item>
    <item name="behavior_skipCollapsed">true</item>
</style>

之后修改Dialog构造方法，引入该样式即可：

public BottomSheetDialogBuyPlan(@NonNull Context context) {
    super(context, R.style.FullScreenBottomSheetDialog);
    // 其余逻辑保持不变
}

Activity调用逻辑无需修改 #

原有调用代码可直接沿用：

BottomSheetDialogBuyPlan bottomSheetDialog = new BottomSheetDialogBuyPlan(getContext());

内容的提问来源于stack exchange，提问作者Malo