Inappwebview 和共享首选项 URL 我无法分配存储在共享首选项中的 url

Question

晚上好。我正在尝试分配共享首选项 url，但页面未加载，它仅在我将值分配给这样的变量时才有效：

String url = 'https://www.youtube.com/';

我试了很多方法还是没能找出哪里出错了，我是flutter的新手，希望大家能帮帮我。

---

这是代码...

import 'package:flutter/material.dart';
import 'package:flutter_inappwebview/flutter_inappwebview.dart';
import 'package:shared_preferences/shared_preferences.dart';

class Webpage extends StatefulWidget {
  const Webpage({super.key});
  @override
  State<Webpage> createState() => _WebpageState();
}

class _WebpageState extends State<Webpage> {
  String initialUrl = '';

  
  @override
  void initState() {
    super.initState();
    main();
  }

  String miStringGlobal = '';

  Future<void> obtenerValorPrefCompartida() async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    miStringGlobal = prefs.getString('link') ?? "https://www.google.com";
  }

  void main() async {
    await obtenerValorPrefCompartida();
  }

  double _progress = 0;
  late InAppWebViewController webView;
  GlobalKey<ScaffoldState> ScaffoldKey = GlobalKey<ScaffoldState>();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      key: ScaffoldKey,
      appBar: AppBar(
        backgroundColor: Color(0xff041f40),
        elevation: 0,
        centerTitle: true,
        title: Text(
          "TEST",
          style: TextStyle(color: const Color.fromARGB(255, 255, 255, 255)),
        ),
      ),
      body: Stack(
        children: [
          InAppWebView(
            initialUrlRequest: URLRequest(url: Uri.parse(miStringGlobal)),
            onWebViewCreated: (InAppWebViewController controller) {
              webView = controller;
            },
            onProgressChanged:
                (InAppWebViewController controller, int progress) {
              setState(() {
                _progress = progress / 100;
              });
            },
          ),
          _progress < 1
              ? SizedBox(
                  height: 3,
                  child: LinearProgressIndicator(
                    value: _progress,
                    backgroundColor: Colors.red.withOpacity(0.2),
                  ),
                )
              : SizedBox()
        ],
      ),
    );
  }
}

我附上了代码，我希望你能告诉我我的错误在哪里。

Answer 1

改变

setState()

值时需要调用

miStringGlobal

来更新UI

更新你的功能

obtenerValorPrefCompartida

到：

  Future<void> obtenerValorPrefCompartida() async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    setState(() {
      miStringGlobal = prefs.getString('link') ?? "https://www.google.com";
    }); 
  }

Answer 2

尝试改变 inti var miStringGlobal

从此

String miStringGlobal = '';

到这个

String miStringGlobal = "https://www.google.com";

如果它加载谷歌那么问题是你的小部件在初始化之前开始构建，在这种情况下

添加一些加载标志

import 'package:flutter/material.dart';
import 'package:flutter_inappwebview/flutter_inappwebview.dart';
import 'package:shared_preferences/shared_preferences.dart';

class Webpage extends StatefulWidget {
 const Webpage({super.key});
 @override
 State<Webpage> createState() => _WebpageState();
}

class _WebpageState extends State<Webpage> {
String initialUrl = '';
bool isloading=false;


 @override
 void initState() {
  super.initState();
  isloading=true;
  main();
  }

  String miStringGlobal = '';

 Future<void> obtenerValorPrefCompartida() async {
 SharedPreferences prefs = await SharedPreferences.getInstance();
 miStringGlobal = prefs.getString('link') ?? "https://www.google.com";
 setState(() {
   isloading=false;
  });
 }

  void main() async {
   await obtenerValorPrefCompartida();    
  
  }

 double _progress = 0;
 late InAppWebViewController webView;
 GlobalKey<ScaffoldState> ScaffoldKey = GlobalKey<ScaffoldState>();

 @override
 Widget build(BuildContext context) {
  return Scaffold(
  key: ScaffoldKey,
  appBar: AppBar(
    backgroundColor: Color(0xff041f40),
    elevation: 0,
    centerTitle: true,
    title: Text(
      "TEST",
      style: TextStyle(color: const Color.fromARGB(255, 255, 255, 255)),
    ),
  ),
  body:isloading?Text("loading"): Stack(
    children: [
      InAppWebView(
        initialUrlRequest: URLRequest(url: Uri.parse(miStringGlobal)),
        onWebViewCreated: (InAppWebViewController controller) {
          webView = controller;
        },
        onProgressChanged:
            (InAppWebViewController controller, int progress) {
          setState(() {
            _progress = progress / 100;
          });
        },
      ),
      _progress < 1
          ? SizedBox(
              height: 3,
              child: LinearProgressIndicator(
                value: _progress,
                backgroundColor: Colors.red.withOpacity(0.2),
              ),
            )
          : SizedBox()
    ],
  ),
);
}
}