return new WillPopScope(

        child: Scaffold(

      body: new Center(

          child: new Column(

        children: <Widget>[

　　　　　　......　　

        ],

      )),

      floatingActionButton: FloatingActionButton(

        onPressed: () => Navigator.pop(context),

//      tooltip: 'Update Text',

        child: Icon(Icons.reply),

      ),

    ),

    onWillPop: (){print("返回键点击了");Navigator.pop(context);});

  }