flutter 点击空白页面 让TextField失去焦点

body:{
    child:  GestureDetector(
        behavior: HitTestBehavior.translucent,
         onTap: () {
             // 触摸收起键盘
              FocusScope.of(context).requestFocus(FocusNode());;
        }
        child: Contariner()
    } 
}