使用这个条子AppBar

SliverAppBar (
        automaticallyImplyLeading: false,
        elevation: 0,
        brightness: Brightness.light,
        backgroundColor: Colors.white,
        pinned: true,
      ),

使用这个正常的Appbar

 appBar: AppBar(
    title: Text
    ("You decide on the appbar name"
    style: TextStyle(color: Colors.black,), 
    elevation: 0,
    brightness: Brightness.light,
    backgroundColor: Colors.white,
    automaticallyImplyLeading: false,

),

您可以通过传递一个空的新Container()作为AppBar的前导参数来删除返回按钮。

如果你发现自己这样做了，你可能不希望用户能够按下设备的后退按钮回到之前的路线。与其调用pushNamed，不如尝试调用Navigator。pushReplacementNamed将导致先前的路由消失。

函数pushReplacementNamed将删除后堆栈中的先前路由，并用新路由替换它。

后者的完整代码示例如下。

import 'package:flutter/material.dart';

class LogoutPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: new Text("Logout Page"),
      ),
      body: new Center(
        child: new Text('You have been logged out'),
      ),
    );
  }

}
class MyHomePage extends StatelessWidget {

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: new Text("Remove Back Button"),
      ),
      floatingActionButton: new FloatingActionButton(
        child: new Icon(Icons.fullscreen_exit),
        onPressed: () {
          Navigator.pushReplacementNamed(context, "/logout");
        },
      ),
    );
  }
}

void main() {
  runApp(new MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'Flutter Demo',
      home: new MyHomePage(),
      routes: {
        "/logout": (_) => new LogoutPage(),
      },
    );
  }
}

如果导航到另一个页面。可以使用Navigator.pushReplacement()。如果你从登录导航到主屏幕，它可以被使用。或者你可以用。 AppBar (automaticallyImplyLeading: false)

使用这个条子AppBar

SliverAppBar (
        automaticallyImplyLeading: false,
        elevation: 0,
        brightness: Brightness.light,
        backgroundColor: Colors.white,
        pinned: true,
      ),

使用这个正常的Appbar

 appBar: AppBar(
    title: Text
    ("You decide on the appbar name"
    style: TextStyle(color: Colors.black,), 
    elevation: 0,
    brightness: Brightness.light,
    backgroundColor: Colors.white,
    automaticallyImplyLeading: false,

),

  appBar: new AppBar(title: new Text("SmartDocs SPAY"),backgroundColor: Colors.blueAccent, automaticallyImplyLeading:false,
        leading: new Container(),
      ),

工作正常

//如果你想隐藏后退按钮使用下面的代码

class SecondScreen extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Scaffold(
  appBar: AppBar(
    title: Text('Remove Back Button'),
    
    //hide back button
    automaticallyImplyLeading: false,
   ),
  body: Center(
    child: Container(),
  ),
);
}
}

//如果你想隐藏后退按钮并停止弹出动作，使用下面的代码

class SecondScreen extends StatelessWidget {

@override
Widget build(BuildContext context) {
 return new WillPopScope(

  onWillPop: () async => false,
  child: Scaffold(
    appBar: AppBar(
      title: Text("Second Screen"),
      //For hide back button
      automaticallyImplyLeading: false,
    ),
    body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          crossAxisAlignment: CrossAxisAlignment.center,
          children: <Widget>[
            RaisedButton(
              child: Text('Back'),
              onPressed: () {
                Navigator.pop(context);
              },
            ),
          ],
        )
    ),
  ),
);
 }