Flutter 每次我重新进入页面时都会调用flatter initState

我有三页，A，B，C，我通过抽屉在它们之间导航

我的目标是使initState只被调用一次（当页面插入小部件树时），这样当我返回到它时，每个页面的状态就不会被重新初始化。

我的第一次尝试是使用

Navigator.of（context）.PushNamed（routeName）

，如下面的代码所示。 可能这不起作用，因为如果我从A调用B，然后再调用A，那么导航器堆栈是

[A] -->[B，A]-->[A，B，A]而不是

[A] ->[B，A]-->[A]

因此，基于pop（）的导航应该更合适。我试过了

onTap: () {
              Navigator.of(context).canPop()
                  ? Navigator.of(context)
                      .popUntil(ModalRoute.withName(PageA.routeName))
                  : Navigator.of(context).pushNamed(PageA.routeName);
            },

而不是

onTap:（）=>Navigator.of（context）.pushNamed（PageA.routeName）

但它不起作用：当我点击抽屉里的物品时，会出现一个黑屏，没有任何异常或警告，好像导航器调用了一个黑屏

我做错了什么？知道怎么修理吗

这是我的代码：

main.dart

import 'package:flutter/material.dart';
import 'page_c.dart';
import 'page_a.dart';
import 'page_b.dart';
void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Navigation test',
      home: PageA(),
      routes: {
        PageA.routeName: (ctx) => PageA(),
        PageB.routeName: (ctx) => PageB(),
        PageC.routeName: (ctx) => PageC(),
      },
    );
  }
}

import 'package:flutter/material.dart';
import 'page_b.dart';
import 'page_c.dart';
import 'page_a.dart';

class MyDrawer extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Drawer(
      child: Column(
        children: [
          SizedBox(
            height: 100,
          ),
          ListTile(
              title: Text('PAGE A'),
              onTap: () => Navigator.of(context).pushNamed(PageA.routeName)),
          ListTile(
              title: Text('PAGE B'),
              onTap: () => Navigator.of(context).pushNamed(PageB.routeName)),
          ListTile(
              title: Text('PAGE C'),
              onTap: () => Navigator.of(context).pushNamed(PageC.routeName)),
        ],
      ),
    );
  }
}

import 'package:flutter/material.dart';
import 'my_drawer.dart';

class PageA extends StatefulWidget {
  static const routeName = '/route-a';

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

class _PageAState extends State<PageA> {
  @override
  void initState() {
    print('PAGE A INIT STATE');
    super.initState();
  }

  // void didChangeDependencies() {
  //   print('PAGE A DID CHANGE DEPENDECIES');
  //   super.didChangeDependencies();
  // }

  // @override
  // void dispose() {
  //   print('PAGE A DISPOSE');
  //   super.dispose();
  // }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('PAGE A')),
      drawer: MyDrawer(),
      body: Center(
        child: Text('A', style: TextStyle(fontSize: 100)),
      ),
    );
  }
}

import 'package:flutter/material.dart';
import 'my_drawer.dart';

class PageB extends StatefulWidget {
  static const routeName = '/route-b';

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

class _PageBState extends State<PageB> {
  @override
  void initState() {
    print('PAGE B INIT STATE');
    super.initState();
  }

  // void didChangeDependencies() {
  //   print('PAGE B DID CHANGE DEPENDECIES');
  //   super.didChangeDependencies();
  // }

  // @override
  // void dispose() {
  //   print('PAGE B DISPOSE');
  //   super.dispose();
  // }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('PAGE B')),
      drawer: MyDrawer(),
      body: Center(
        child: Text('B', style: TextStyle(fontSize: 100)),
      ),
    );
  }
}

import 'package:flutter/material.dart';
import 'my_drawer.dart';

class PageC extends StatefulWidget {
  static const routeName = '/route-c';

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

class _PageCState extends State<PageC> {
  @override
  void initState() {
    print('PAGE C INIT STATE');
    super.initState();
  }

  // void didChangeDependencies() {
  //   print('PAGE C DID CHANGE DEPENDECIES');
  //   super.didChangeDependencies();
  // }

  // @override
  // void dispose() {
  //   print('PAGE C DISPOSE');
  //   super.dispose();
  // }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('PAGE C')),
      drawer: MyDrawer(),
      body: Center(
        child: Text('C', style: TextStyle(fontSize: 100)),
      ),
    );
  }
}

我的抽屉。飞镖

import 'package:flutter/material.dart';
import 'page_c.dart';
import 'page_a.dart';
import 'page_b.dart';
void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Navigation test',
      home: PageA(),
      routes: {
        PageA.routeName: (ctx) => PageA(),
        PageB.routeName: (ctx) => PageB(),
        PageC.routeName: (ctx) => PageC(),
      },
    );
  }
}

import 'package:flutter/material.dart';
import 'page_b.dart';
import 'page_c.dart';
import 'page_a.dart';

class MyDrawer extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Drawer(
      child: Column(
        children: [
          SizedBox(
            height: 100,
          ),
          ListTile(
              title: Text('PAGE A'),
              onTap: () => Navigator.of(context).pushNamed(PageA.routeName)),
          ListTile(
              title: Text('PAGE B'),
              onTap: () => Navigator.of(context).pushNamed(PageB.routeName)),
          ListTile(
              title: Text('PAGE C'),
              onTap: () => Navigator.of(context).pushNamed(PageC.routeName)),
        ],
      ),
    );
  }
}

import 'package:flutter/material.dart';
import 'my_drawer.dart';

class PageA extends StatefulWidget {
  static const routeName = '/route-a';

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

class _PageAState extends State<PageA> {
  @override
  void initState() {
    print('PAGE A INIT STATE');
    super.initState();
  }

  // void didChangeDependencies() {
  //   print('PAGE A DID CHANGE DEPENDECIES');
  //   super.didChangeDependencies();
  // }

  // @override
  // void dispose() {
  //   print('PAGE A DISPOSE');
  //   super.dispose();
  // }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('PAGE A')),
      drawer: MyDrawer(),
      body: Center(
        child: Text('A', style: TextStyle(fontSize: 100)),
      ),
    );
  }
}

import 'package:flutter/material.dart';
import 'my_drawer.dart';

class PageB extends StatefulWidget {
  static const routeName = '/route-b';

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

class _PageBState extends State<PageB> {
  @override
  void initState() {
    print('PAGE B INIT STATE');
    super.initState();
  }

  // void didChangeDependencies() {
  //   print('PAGE B DID CHANGE DEPENDECIES');
  //   super.didChangeDependencies();
  // }

  // @override
  // void dispose() {
  //   print('PAGE B DISPOSE');
  //   super.dispose();
  // }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('PAGE B')),
      drawer: MyDrawer(),
      body: Center(
        child: Text('B', style: TextStyle(fontSize: 100)),
      ),
    );
  }
}

import 'package:flutter/material.dart';
import 'my_drawer.dart';

class PageC extends StatefulWidget {
  static const routeName = '/route-c';

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

class _PageCState extends State<PageC> {
  @override
  void initState() {
    print('PAGE C INIT STATE');
    super.initState();
  }

  // void didChangeDependencies() {
  //   print('PAGE C DID CHANGE DEPENDECIES');
  //   super.didChangeDependencies();
  // }

  // @override
  // void dispose() {
  //   print('PAGE C DISPOSE');
  //   super.dispose();
  // }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('PAGE C')),
      drawer: MyDrawer(),
      body: Center(
        child: Text('C', style: TextStyle(fontSize: 100)),
      ),
    );
  }
}

页码a.省道

import 'package:flutter/material.dart';
import 'page_c.dart';
import 'page_a.dart';
import 'page_b.dart';
void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Navigation test',
      home: PageA(),
      routes: {
        PageA.routeName: (ctx) => PageA(),
        PageB.routeName: (ctx) => PageB(),
        PageC.routeName: (ctx) => PageC(),
      },
    );
  }
}

import 'package:flutter/material.dart';
import 'page_b.dart';
import 'page_c.dart';
import 'page_a.dart';

class MyDrawer extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Drawer(
      child: Column(
        children: [
          SizedBox(
            height: 100,
          ),
          ListTile(
              title: Text('PAGE A'),
              onTap: () => Navigator.of(context).pushNamed(PageA.routeName)),
          ListTile(
              title: Text('PAGE B'),
              onTap: () => Navigator.of(context).pushNamed(PageB.routeName)),
          ListTile(
              title: Text('PAGE C'),
              onTap: () => Navigator.of(context).pushNamed(PageC.routeName)),
        ],
      ),
    );
  }
}

import 'package:flutter/material.dart';
import 'my_drawer.dart';

class PageA extends StatefulWidget {
  static const routeName = '/route-a';

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

class _PageAState extends State<PageA> {
  @override
  void initState() {
    print('PAGE A INIT STATE');
    super.initState();
  }

  // void didChangeDependencies() {
  //   print('PAGE A DID CHANGE DEPENDECIES');
  //   super.didChangeDependencies();
  // }

  // @override
  // void dispose() {
  //   print('PAGE A DISPOSE');
  //   super.dispose();
  // }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('PAGE A')),
      drawer: MyDrawer(),
      body: Center(
        child: Text('A', style: TextStyle(fontSize: 100)),
      ),
    );
  }
}

import 'package:flutter/material.dart';
import 'my_drawer.dart';

class PageB extends StatefulWidget {
  static const routeName = '/route-b';

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

class _PageBState extends State<PageB> {
  @override
  void initState() {
    print('PAGE B INIT STATE');
    super.initState();
  }

  // void didChangeDependencies() {
  //   print('PAGE B DID CHANGE DEPENDECIES');
  //   super.didChangeDependencies();
  // }

  // @override
  // void dispose() {
  //   print('PAGE B DISPOSE');
  //   super.dispose();
  // }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('PAGE B')),
      drawer: MyDrawer(),
      body: Center(
        child: Text('B', style: TextStyle(fontSize: 100)),
      ),
    );
  }
}

import 'package:flutter/material.dart';
import 'my_drawer.dart';

class PageC extends StatefulWidget {
  static const routeName = '/route-c';

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

class _PageCState extends State<PageC> {
  @override
  void initState() {
    print('PAGE C INIT STATE');
    super.initState();
  }

  // void didChangeDependencies() {
  //   print('PAGE C DID CHANGE DEPENDECIES');
  //   super.didChangeDependencies();
  // }

  // @override
  // void dispose() {
  //   print('PAGE C DISPOSE');
  //   super.dispose();
  // }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('PAGE C')),
      drawer: MyDrawer(),
      body: Center(
        child: Text('C', style: TextStyle(fontSize: 100)),
      ),
    );
  }
}

导入“包装：颤振/材料.省道”；
导入“my_drawer.dart”；
类PageA扩展了StatefulWidget{
静态常量routeName='/route-a'；
@凌驾
_PageAState createState（）=>\u PageAState（）；
}
类_PageAState扩展状态{
@凌驾
void initState（）{
打印（“页面A初始状态”）；
super.initState（）；
}
//void didChangeDependencies（）{
//打印（“A页未更改依赖项”）；
//super.didChangeDependencies（）；
// }
//@覆盖
//无效处置（）{
//打印（A页）；
//super.dispose（）；
// }
@凌驾
小部件构建（构建上下文）{
返回脚手架(
appBar:appBar（标题：文本（“A页”），
抽屉：MyDrawer（），
正文：中(
子项：文本（'A'，样式：TextStyle（fontSize:100）），
),
);
}
}

省道页面

import 'package:flutter/material.dart';
import 'page_c.dart';
import 'page_a.dart';
import 'page_b.dart';
void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Navigation test',
      home: PageA(),
      routes: {
        PageA.routeName: (ctx) => PageA(),
        PageB.routeName: (ctx) => PageB(),
        PageC.routeName: (ctx) => PageC(),
      },
    );
  }
}

import 'package:flutter/material.dart';
import 'page_b.dart';
import 'page_c.dart';
import 'page_a.dart';

class MyDrawer extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Drawer(
      child: Column(
        children: [
          SizedBox(
            height: 100,
          ),
          ListTile(
              title: Text('PAGE A'),
              onTap: () => Navigator.of(context).pushNamed(PageA.routeName)),
          ListTile(
              title: Text('PAGE B'),
              onTap: () => Navigator.of(context).pushNamed(PageB.routeName)),
          ListTile(
              title: Text('PAGE C'),
              onTap: () => Navigator.of(context).pushNamed(PageC.routeName)),
        ],
      ),
    );
  }
}

import 'package:flutter/material.dart';
import 'my_drawer.dart';

class PageA extends StatefulWidget {
  static const routeName = '/route-a';

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

class _PageAState extends State<PageA> {
  @override
  void initState() {
    print('PAGE A INIT STATE');
    super.initState();
  }

  // void didChangeDependencies() {
  //   print('PAGE A DID CHANGE DEPENDECIES');
  //   super.didChangeDependencies();
  // }

  // @override
  // void dispose() {
  //   print('PAGE A DISPOSE');
  //   super.dispose();
  // }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('PAGE A')),
      drawer: MyDrawer(),
      body: Center(
        child: Text('A', style: TextStyle(fontSize: 100)),
      ),
    );
  }
}

import 'package:flutter/material.dart';
import 'my_drawer.dart';

class PageB extends StatefulWidget {
  static const routeName = '/route-b';

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

class _PageBState extends State<PageB> {
  @override
  void initState() {
    print('PAGE B INIT STATE');
    super.initState();
  }

  // void didChangeDependencies() {
  //   print('PAGE B DID CHANGE DEPENDECIES');
  //   super.didChangeDependencies();
  // }

  // @override
  // void dispose() {
  //   print('PAGE B DISPOSE');
  //   super.dispose();
  // }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('PAGE B')),
      drawer: MyDrawer(),
      body: Center(
        child: Text('B', style: TextStyle(fontSize: 100)),
      ),
    );
  }
}

import 'package:flutter/material.dart';
import 'my_drawer.dart';

class PageC extends StatefulWidget {
  static const routeName = '/route-c';

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

class _PageCState extends State<PageC> {
  @override
  void initState() {
    print('PAGE C INIT STATE');
    super.initState();
  }

  // void didChangeDependencies() {
  //   print('PAGE C DID CHANGE DEPENDECIES');
  //   super.didChangeDependencies();
  // }

  // @override
  // void dispose() {
  //   print('PAGE C DISPOSE');
  //   super.dispose();
  // }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('PAGE C')),
      drawer: MyDrawer(),
      body: Center(
        child: Text('C', style: TextStyle(fontSize: 100)),
      ),
    );
  }
}

导入“包装：颤振/材料.省道”；
导入“my_drawer.dart”；
类PageB扩展了StatefulWidget{
静态常量routeName='/route-b'；
@凌驾
_PageBState createState（）=>\u PageBState（）；
}
类_PageBState扩展状态{
@凌驾
void initState（）{
打印（“页面B初始状态”）；
super.initState（）；
}
//void didChangeDependencies（）{
//打印（“B页未更改依赖项”）；
//super.didChangeDependencies（）；
// }
//@覆盖
//无效处置（）{
//打印（第B页）；
//super.dispose（）；
// }
@凌驾
小部件构建（构建上下文）{
返回脚手架(
appBar:appBar（标题：文本（“B页”），
抽屉：MyDrawer（），
正文：中(
子项：文本（'B'，样式：文本样式（fontSize:100）），
),
);
}
}

第三页省道

import 'package:flutter/material.dart';
import 'page_c.dart';
import 'page_a.dart';
import 'page_b.dart';
void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Navigation test',
      home: PageA(),
      routes: {
        PageA.routeName: (ctx) => PageA(),
        PageB.routeName: (ctx) => PageB(),
        PageC.routeName: (ctx) => PageC(),
      },
    );
  }
}

import 'package:flutter/material.dart';
import 'page_b.dart';
import 'page_c.dart';
import 'page_a.dart';

class MyDrawer extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Drawer(
      child: Column(
        children: [
          SizedBox(
            height: 100,
          ),
          ListTile(
              title: Text('PAGE A'),
              onTap: () => Navigator.of(context).pushNamed(PageA.routeName)),
          ListTile(
              title: Text('PAGE B'),
              onTap: () => Navigator.of(context).pushNamed(PageB.routeName)),
          ListTile(
              title: Text('PAGE C'),
              onTap: () => Navigator.of(context).pushNamed(PageC.routeName)),
        ],
      ),
    );
  }
}

import 'package:flutter/material.dart';
import 'my_drawer.dart';

class PageA extends StatefulWidget {
  static const routeName = '/route-a';

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

class _PageAState extends State<PageA> {
  @override
  void initState() {
    print('PAGE A INIT STATE');
    super.initState();
  }

  // void didChangeDependencies() {
  //   print('PAGE A DID CHANGE DEPENDECIES');
  //   super.didChangeDependencies();
  // }

  // @override
  // void dispose() {
  //   print('PAGE A DISPOSE');
  //   super.dispose();
  // }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('PAGE A')),
      drawer: MyDrawer(),
      body: Center(
        child: Text('A', style: TextStyle(fontSize: 100)),
      ),
    );
  }
}

import 'package:flutter/material.dart';
import 'my_drawer.dart';

class PageB extends StatefulWidget {
  static const routeName = '/route-b';

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

class _PageBState extends State<PageB> {
  @override
  void initState() {
    print('PAGE B INIT STATE');
    super.initState();
  }

  // void didChangeDependencies() {
  //   print('PAGE B DID CHANGE DEPENDECIES');
  //   super.didChangeDependencies();
  // }

  // @override
  // void dispose() {
  //   print('PAGE B DISPOSE');
  //   super.dispose();
  // }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('PAGE B')),
      drawer: MyDrawer(),
      body: Center(
        child: Text('B', style: TextStyle(fontSize: 100)),
      ),
    );
  }
}

import 'package:flutter/material.dart';
import 'my_drawer.dart';

class PageC extends StatefulWidget {
  static const routeName = '/route-c';

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

class _PageCState extends State<PageC> {
  @override
  void initState() {
    print('PAGE C INIT STATE');
    super.initState();
  }

  // void didChangeDependencies() {
  //   print('PAGE C DID CHANGE DEPENDECIES');
  //   super.didChangeDependencies();
  // }

  // @override
  // void dispose() {
  //   print('PAGE C DISPOSE');
  //   super.dispose();
  // }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('PAGE C')),
      drawer: MyDrawer(),
      body: Center(
        child: Text('C', style: TextStyle(fontSize: 100)),
      ),
    );
  }
}

导入“包装：颤振/材料.省道”；
导入“my_drawer.dart”；
类PageC扩展了StatefulWidget{
静态常量routeName='/route-c'；
@凌驾
_PageCState createState（）=>\u PageCState（）；
}
类_PageCState扩展状态{
@凌驾
void initState（）{
打印（“第C页初始状态”）；
super.initState（）；
}
//void didChangeDependencies（）{
//打印（“C页未更改依赖项”）；
//super.didChangeDependencies（）；
// }
//@覆盖
//无效处置（）{
//打印（C页）；
//super.dispose（）；
// }
@凌驾
小部件构建（构建上下文）{
返回脚手架(
appBar:appBar（标题：文本（“C页”），
抽屉：MyDrawer（），
正文：中(
子项：文本（'C'，样式：TextStyle（fontSize:100）），
),
);
}
}

navigator的pushNamed方法在每次调用页面时为其创建一个新实例，这是正常的。如果你想保持你的页面状态，我认为你应该在一个容器中显示/隐藏你的页面。导航器的pushNamed方法在你每次调用它时都会为你的页面创建一个新的实例，这很正常。如果你想保持你的页面状态，我认为你应该在一个容器中显示/隐藏你的页面。