Flutter 局部路由实现详解

import 'package:flutter/material.dart';class NavigatorPage extends StatefulWidget { @override _NavigatorPageState createState() => _NavigatorPageState();}class _NavigatorPageState extends State<NavigatorPage> { @override Widget build(BuildContext context) {  return Scaffold(   appBar: AppBar(    title: Text('Navigator'),   ),   body: Column(    children: <Widget>[     Text('Navigator的高度为infinity'),     Text('如果直接父级非最上级也是infinity会产生异常'),     Container(      height: 333,      color: Colors.amber.withAlpha(111),      child: Navigator( // Navigator       initialRoute: '/abc',       onGenerateRoute: (val) {        RoutePageBuilder builder;        switch (val.name) {         case '/abc':          builder = (BuildContext nContext, Animation<double> animation, Animation<double> secondaryAnimation) => Column(           // 并没有在 MaterialApp 中设定 /efg 路由           // 因为Navigator的特性 使用nContext 可以跳转 /efg           children: <Widget>[            Text('呵呵呵'),            RaisedButton(             child: Text('去 /efg'),             onPressed: () {              Navigator.pushNamed(nContext, '/efg');             },            )           ],          );         break;         case '/efg':          builder = (BuildContext nContext, Animation<double> animation, Animation<double> secondaryAnimation) => Row(           children: <Widget>[            RaisedButton(             child: Text('去 /hhh'),             onPressed: () {              Navigator.pushNamed(nContext, '/hhh');             },            )           ],          );         break;         default:          builder = (BuildContext nContext, Animation<double> animation, Animation<double> secondaryAnimation) => Center(           child: RaisedButton(            child: Text('去 /abc'),            onPressed: () {             Navigator.pushNamed(nContext, '/abc');            },           )          );        }        return PageRouteBuilder(         pageBuilder: builder,         // transitionDuration: const Duration(milliseconds: 0),        );       },       onUnknownRoute: (val) {        print(val);       },       observers: <NavigatorObserver>[]      ),     ),     Text('Navigator执行寻找路由顺序'),     Text('initialRoute'),     Text('onGenerateRoute'),     Text('onUnknownRoute'),    ],   ),  ); }}