flutter - Flutter-如何在按下“后退”按钮时重定向到特定事件？

Question

我想在按下返回按钮时将我当前的 flutter 页面重定向到主页，将重定向。当我按返回按钮时，主页/ Activity 应开始。我在主页中有多种选择，在当前页面中，如果用户不想选择它们，我可以显示眼睛，可以按返回首页。

这是我当前页面/ Activity 的代码

import '../DataFetching/face_part.dart';
import 'package:flutter/material.dart';




class EyesFetch extends StatelessWidget {


 // This widget is the root of your application.
 @override
 Widget build(BuildContext context) {
 return MaterialApp(
 title: 'Flutter Demo',
 theme: ThemeData(
 // This is the theme of your application.
 //
 // Try running your application with "flutter run". You'll see the
 // application has a blue toolbar. Then, without quitting the app, try
 // changing the primarySwatch below to Colors.green and then invoke
 // "hot reload" (press "r" in the console where you ran "flutter run",
 // or simply save your changes to "hot reload" in a Flutter IDE).
 // Notice that the counter didn't reset back to zero; the application
 // is not restarted.
 primarySwatch: Colors.blue,
 ),
 home: MyHomePage(),
 );
 }

}

class MyHomePage extends StatefulWidget {


 @override
 _DataFetching createState() => _DataFetching();
}

class _DataFetching extends State<MyHomePage>{
 Future<List<facial>> list = facial.alleyes();
 List<facial> alleyes=new List<facial>();

 @override
 Widget build(BuildContext context) {
 return Scaffold(
 appBar: AppBar(

 title: Text("fetch"),
 ),
 body: Center(
 child: Column(
 mainAxisAlignment: MainAxisAlignment.center,
 children: <Widget>[

 new FutureBuilder<List<facial>>(
 future: list, // a previously-obtained Future<String> or null
 builder: (BuildContext context, AsyncSnapshot<List<facial>> snapshot) {

 List<Widget> children;
 if (snapshot.hasData) {
 var result=snapshot.data;
 for(var item in result)
 {
 alleyes.add(new facial(criminal_id: item.criminal_id,
 part_size: item.part_size,
 link: item.link));
 }
 children = <Widget>[

 new Padding(
 padding: EdgeInsets.fromLTRB(0.0, 10.0, 0.0, 0.0),
 child: getHomePageBody(context))

 ];
 } else if (snapshot.hasError) {
 children = <Widget>[
 Icon(
 Icons.error_outline,
 color: Colors.red,
 size: 60,
 ),
 Padding(
 padding: const EdgeInsets.only(top: 16),
 child: Text('Error: ${snapshot.error}'),
 )
 ];
 } else {
 children = <Widget>[
 SizedBox(
 child: CircularProgressIndicator(),
 width: 60,
 height: 60,
 ),

 ];
 }
 return Center(
 child: Column(
 mainAxisAlignment: MainAxisAlignment.start,
 crossAxisAlignment: CrossAxisAlignment.start,
 children: children,
 ),
 );
 },
 ),


 ]// This trailing comma makes auto-formatting nicer for build methods.
 )));

 }

 getHomePageBody(BuildContext context) {
 final _screenSize = MediaQuery.of(context).size;
 return Container(
 height: _screenSize.height * 0.85,
 child:
 new GridView.builder(
 scrollDirection: Axis.vertical,
 shrinkWrap: true,
 itemCount: alleyes.length,
 gridDelegate:
 SliverGridDelegateWithFixedCrossAxisCount (crossAxisCount: 3),

 itemBuilder: (context,index){
 return _getItemUI(context,index);
 }));
 }
 Widget _getItemUI(BuildContext context, int index) {

 return Container(

 child: Card(

 child:

 new Image.network(alleyes[index].link, fit: BoxFit.cover),



 ),


 );
 }


}

那么我在这里可以使用什么来实现后按功能呢？

Answer 1

您可以在WillPopScope小部件的帮助下处理Flutter中的后退事件。你会发现onWillPop方法

@override
Widget build(BuildContext context) {
  return WillPopScope(
    onWillPop: _onBackPressed,
    child: new Scaffold(
      appBar: new AppBar(
        title: new Text(
          "On Back pressed",
          style: new TextStyle(color: Colors.white),
        ),
      ),
      body: new Center(
        child: new Text("Home Page"),
      ),
    ),
  );
}

使用您想在背面按一下的方法来实现_onBackPressed方法:

Future<bool> _onBackPressed() {
  return ANYTHING YOU WANT TO DO ??
      false;
}

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