如何像软键盘一样在根布局的底部设置PopupWindow？

// 创建根布局
LinearLayout rootLayout = findViewById(R.id.root_layout);

// 添加底部占位View
View bottomView = new View(this);
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, 0);
params.weight = 1;
rootLayout.addView(bottomView, params);

// 加载PopupWindow的布局文件
View popupView = LayoutInflater.from(this).inflate(R.layout.popup_layout, null);

// 创建PopupWindow对象
PopupWindow popupWindow = new PopupWindow(popupView, ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);
popupWindow.setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));
popupWindow.setOutsideTouchable(true);

// 设置PopupWindow的显示位置
popupWindow.showAtLocation(bottomView, Gravity.BOTTOM, 0, 0);

// 设置PopupWindow的动画效果
popupWindow.setAnimationStyle(R.style.PopupAnimation);

// 底部占位View的点击事件
bottomView.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        if (popupWindow.isShowing()) {
            popupWindow.dismiss();
        } else {
            popupWindow.showAtLocation(bottomView, Gravity.BOTTOM, 0, 0);
        }
    }
});