我正在开发一个具有超过 5 个屏幕的颤振应用程序，我想处理 android 的后退按钮，例如，当我登录应用程序时，它会显示仪表板屏幕，所以当我移动到配置文件然后移动到历史屏幕，当我点击历史屏幕上的后退按钮时，它应该导航到个人资料屏幕，因为我在历史屏幕之前访问的最后一个屏幕是个人资料，但它显示了登录屏幕的第一个屏幕。
我找到了解决方案，当我单击后退按钮时它会关闭应用程序。
更新：
我的屏幕从抽屉和底部导航导航，只有登录屏幕，我使用登录按钮并调用仪表板屏幕 onpressed 功能，除此之外，任何屏幕上都没有导航到其他屏幕的按钮。这是抽屉和底部导航的代码。
这是我在登录按钮上使用的代码行
Navigator.push(
context, new MaterialPageRoute(builder: (context) => Employee()));
抽屉和底部导航代码： 代码：
class Employee extends StatelessWidget {
@override
Widget build(BuildContext context) {
return new MaterialApp(
debugShowCheckedModeBanner: false,
theme: new ThemeData(
primaryColor: Colors.blue
),
home: EmployeeNavigation(),
);
}
}
int _selectedTab = 0;
final _pageOptions = [
EmployeeDashboard(),
location(),
Profile()
];
String getname="";
String getemail="";
String getdesignation="";
String getaccesstoken="";
String getdate;
String getTime;
// ignore: must_be_immutable
class EmployeeNavigation extends StatefulWidget {
@override
State<StatefulWidget> createState() {
return EmployeeNavigationState();
}
}
class EmployeeNavigationState extends State<EmployeeNavigation> {
var email;
var designation;
var date;
bool valuefirst = false;
String backtext="";
@override
Widget build(BuildContext context) {
//i used this too but it doesn't work.
return WillPopScope(
onWillPop: () async {
if (_selectedTab == 0) {
return true;
}
setState(() {
_selectedTab = 0;
});
return false;
},
child:Scaffold(
drawer:Emp_DrawerCode(),
body: _pageOptions[_selectedTab],
bottomNavigationBar: BottomNavigationBar(
backgroundColor: Colors.blue[50],
type: BottomNavigationBarType.fixed,
currentIndex: _selectedTab,
onTap: (value) {
print(value);
setState(() {
_selectedTab = value;
});
},
items: [
BottomNavigationBarItem(icon: Icon(Icons.home), label: "Home"),
BottomNavigationBarItem(icon: Icon(Icons.location_on), label: "Location"),
BottomNavigationBarItem(
icon: Icon(Icons.person),
label: "Profile",
),
],
)));
}
}
class Emp_DrawerCode extends StatefulWidget {
@override
_Emp_DrawerCodeState createState() => _Emp_DrawerCodeState();
}
class _Emp_DrawerCodeState extends State<Emp_DrawerCode> {
SharedPreferences myPrefs;
name() async{
myPrefs=await SharedPreferences.getInstance();
setState(() {
getname=myPrefs.getString('name');
getemail=myPrefs.getString('email');
getdesignation=myPrefs.getString('designation');
});
}
void initState(){
name();
}
@override
Widget build(BuildContext context) {
return new Drawer(
child: new ListView(
padding: const EdgeInsets.all(0.0),
children: <Widget>[
new UserAccountsDrawerHeader(
accountName: new Text(getname),
accountEmail: new Text(getemail),
currentAccountPicture: new CircleAvatar(
backgroundColor:
Theme.of(context).platform == TargetPlatform.android
? Colors.white
: Colors.blue,
child: Text(
getname[0][0],
style: TextStyle(fontSize: 40.0),
),
),
),
new ListTile(
title: new Text('Home'),
leading: Icon(Icons.dashboard,color:Colors.grey),
onTap: (){
Navigator.pop(context);
Navigator.push(context, new MaterialPageRoute(
builder: (context)=> EmployeeNavigation()
)
);
},
),
new ListTile(
title: new Text('Request for leave'),
leading: Icon(Icons.request_page,color:Colors.grey),
onTap: (){
Navigator.pop(context);
Navigator.push(context, new MaterialPageRoute(
builder: (context)=>RequestForLeave()
)
);
},
),
new ExpansionTile(
title: new Text('History'),
children: <Widget>[
ListTile(
title:new Text("My Attendance"),
leading: Icon(Icons.assessment_outlined ,color:Colors.grey),
onTap: (){
Navigator.pop(context);
Navigator.push(context, new MaterialPageRoute(
builder: (context)=>new MyAttendance()
)
);
},
),
ListTile(
title:new Text("Leaves"),
leading: Icon(Icons.assessment_outlined,color:Colors.grey ),
onTap: (){
Navigator.pop(context);
Navigator.push(context, new MaterialPageRoute(
builder: (context)=>new LeaveHistory()
)
);
},
),
],
leading: Icon(Icons.history,),
),
new ListTile(
title: new Text('Log out'),
leading: Icon(Icons.logout,color:Colors.grey),
onTap: (){
myPrefs.setBool('login', true);
Navigator.pop(context);
Navigator.push(context, new MaterialPageRoute(
builder: (context)=>
Login()
)
);
},
),
],
),
);
}
}
请帮助如何做到这一点。