import dartasync;import packagediodiodart;import packagefluttermaterialdart;import packagemuse_nepu_courseglobaldart;import packagepretty_qr_codepretty_qr_codedart;import packageslide_countdownslide_c

可以在Scaffold的appBar中添加一个IconButton，点击后触发刷新二维码的操作。代码如下：

... appBar: AppBar( backgroundColor: Global.home_currentcolor, actions: [ IconButton( icon: Icon(Icons.refresh), onPressed: () { Global().getqr(); _countdownTime = 50; streamDuration.change(Duration(seconds: 51)); setState(() {}); }, ), ], ), body: Column( mainAxisAlignment: MainAxisAlignment.center, children: [ TextButton( child: Text('点击刷新二维码'), onPressed: () { Global().getqr(); _countdownTime = 50; streamDuration.change(Duration(seconds: 51)); setState(() {}); }, ), ... ], ), ..