Android popwindow位于某控件底部

1：点击需要弹框按钮传控件id（popwindow显示在哪个view下方就传哪个id）

  case R.id.edit_dz:
                showPopupWindow(editDz);
                break;

2：显示弹框

 private void showPopupWindow(TextView view) {
        //加载布局
        View inflate = LayoutInflater.from(VipRZActivity.this).inflate(R.layout.popupwindow_dz, null);
        //更改背景颜色透明
        setBackgroundAlpha(VipRZActivity.this, 1f);
        mPopupWindow = new PopupWindow(inflate);
        //必须设置宽和高
        mPopupWindow.setWidth(540);
        mPopupWindow.setHeight(RelativeLayout.LayoutParams.WRAP_CONTENT);
        //点击其他地方隐藏,false为无反应
        mPopupWindow.setFocusable(true);
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
            //对他进行偏移
            mPopupWindow.showAsDropDown(view, 0, 0, Gravity.BOTTOM);
        }
        mDzrecy = inflate.findViewById(R.id.pop_dzrecy);
     	//内容显示操作
     	
        //对popupWindow进行显示
        mPopupWindow.update();
    }

  //设置屏幕背景透明效果
    public static void setBackgroundAlpha(Activity activity, float alpha) {
        WindowManager.LayoutParams lp = activity.getWindow().getAttributes();
        lp.alpha = alpha;
        activity.getWindow().setAttributes(lp);
    }