Flutter应用程序后退按钮事件未重定向到后页 [英] Flutter app back button event not redirecting to back page

问题描述

我正在开发一款轻量级的android应用.它具有三个屏幕.页面1，页面2，页面3.当我从页面2输入页面3时.如果单击电话后退按钮，它想转到页面2.但是它正在重定向到页面1.我在从那里获得引用后尝试了在Flutter上捕获Android后退按钮事件

I am developing a flutter android app. It have three screens. Page 1, Page 2, Page 3. When i entering Page 3 from Page 2. if i click phone back button it want to got to page 2. But it is redirecting to page 1. I tried after got the reference from catch Android back button event on Flutter

我尝试了 WillPopScope .它没有输入 onWillPop .

I tried WillPopScope . It is not entering in onWillPop .

如何解决问题.我的代码如下所示.

How to solve the problem. My code is shown below.

第1页

    void main() => runApp(MyApp());
    class MyApp extends StatelessWidget {
    // This widget is the root of your application.
    @override
    Widget build(BuildContext context) {
        return MaterialApp(
        home: Scaffold(
            appBar: new AppBar(),
            body: MyAppPage()
        ),
        );
    }
    }

    class MyAppPage extends StatefulWidget{
    MyAppPage({Key key,}):super(key:key);

    @override
    _MyAppPageState createState()=> new _MyAppPageState();
    }

    class _MyAppPageState extends State<MyAppPage>{

    @override
    Widget build(BuildContext context){
        return new Scaffold(
        body:RaisedButton(onPressed:(){ Navigator.push(context, MaterialPageRoute(builder: (context) => SecondScreen()));},
        child: new Text("got to page 1"),)
        );
    }
    }

第2页

    class SecondScreen extends StatelessWidget{
    @override
    Widget build(BuildContext context) {
        return MaterialApp(
        home: Scaffold(
            appBar: new AppBar(),
            body: SecondPage()
        ),
        );
    }
    }

    class SecondPage extends StatefulWidget{
    SecondPage({Key key,}):super(key:key);
    @override
    SecondPageState createState()=> new SecondPageState();
    }

    class SecondPageState extends State<SecondPage>{
    @override
    Widget build(BuildContext context){
        return new Scaffold(
            body:Column(
            children: <Widget>[
                new Center(
                child: new Text("Page 2"),
                ),
                RaisedButton(onPressed:(){ Navigator.push(context, MaterialPageRoute(builder: (context) => ThirdScreen()));},
                child: new Text("go to third Page 3"),)
            ],
            )
        );
    }
    }

第3页

    class ThirdScreen extends StatelessWidget{
    @override
    Widget build(BuildContext context) {
        return MaterialApp(
        home: Scaffold(
            appBar: new AppBar(),
            body: ThirdPage()
        ),
        );
    }
    }

    class ThirdPage extends StatefulWidget{
    ThirdPage({Key key,}):super(key:key);
    @override
    ThirdPageState createState()=> new ThirdPageState();
    }

    class ThirdPageState extends State<ThirdPage>{
    @override
    Widget build(BuildContext context){
        return new WillPopScope(
        child: new Scaffold(
            body:  new Center(
            child: new Text('PAGE 3'),
            ),
        ),
        onWillPop: (){
            debugPrint("onWillPop");
            return new Future(() => false);
        },
        );
    }
    }

推荐答案

您对创建的 Screen 和 Pages 感到困惑.实际上，您拥有的小部件数量超出了您的需求.

You kinda got confused with the Screen and Pages you created. You actually have more Widgets than you need.

这可能是您想要做的.

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(home: MyAppPage());
  }
}

class MyAppPage extends StatefulWidget {
  @override
  _MyAppPageState createState() => _MyAppPageState();
}

class _MyAppPageState extends State<MyAppPage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text("Page 1")),
      body: Column(
        mainAxisAlignment: MainAxisAlignment.spaceEvenly,
        children: <Widget>[
          Center(child: Text("got to page 1")),
          RaisedButton(
            child: Text("Go to Page 2"),
            onPressed: () {
              Navigator.push(context, MaterialPageRoute(builder: (context) => SecondPage()));
            },
          ),
        ],
      ),
    );
  }
}

class SecondPage extends StatefulWidget {
  @override
  _SecondPageState createState() => _SecondPageState();
}

class _SecondPageState extends State<SecondPage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text("Page 2")),
      body: Column(
        mainAxisAlignment: MainAxisAlignment.spaceEvenly,
        children: <Widget>[
          Center(
            child: Text("I'm in Page 2"),
          ),
          RaisedButton(
            onPressed: () {
              Navigator.push(context,
                  MaterialPageRoute(builder: (context) => ThirdPage()));
            },
            child: Text("go to third Page 3"),
          )
        ],
      )
    );
  }
}

class ThirdPage extends StatefulWidget {
  @override
  _ThirdPageState createState() => _ThirdPageState();
}

class _ThirdPageState extends State<ThirdPage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text("Page 3")),
      body: Column(
        mainAxisAlignment: MainAxisAlignment.spaceEvenly,
        children: <Widget>[
          Center(child: Text('PAGE 3')),
          RaisedButton(
            child: Text("aditional back button"),
            onPressed: () => Navigator.of(context).pop(),
          ),
        ],
      ),
    );
  }
}

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