通过事件打开侧边栏

return Scaffold(
  key:_scaffoldKey,
  appBar: AppBar(
    title: Text("商品列表"),
  )
)

Expanded(
  flex: 1,
  child: InkWell(
    child: Padding(
      padding: EdgeInsets.fromLTRB(
          0, ScreenAdaper.height(16), 0, ScreenAdaper.height(16)),
      child: Text("筛选", textAlign: TextAlign.center),
    ),
    onTap: () {
      _scaffoldKey.currentState.openEndDrawer();
    },
  ),
),