Flutter 使用WebView并写入LocalStorage内容

import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'package:webview_flutter/webview_flutter.dart';
class GroupWebViewBox extends StatefulWidget {
  final String url;
  GroupWebViewBox({Key key, @required this.url}):super(key: key);
  @override
  _GroupWebViewBoxState createState() => _GroupWebViewBoxState();
}
class _GroupWebViewBoxState extends State<GroupWebViewBox> {
  bool isLoading = true;
  WebViewController _webViewController;
  /*写入token到Cookie*/
  // setcookie() async {
  //   if (_bloc.state.user != null) {
  //     _webViewController.evaluateJavascript('document.cookie="token=${_bloc.state.user.token};"');
  //     _webViewController.evaluateJavascript('document.cookie="app.domain=$host;"');
  //   }
  // }
  /*写入token到localStorage*/
  setlocalStorage() async {
    final prefs = await SharedPreferences.getInstance();
    var token = prefs.getString('token');
    _webViewController.evaluateJavascript(
      """
      function setToken() {
        setTimeout(function() {
          if(localStorage) {
            localStorage.setItem('token','$token');
          }else {
            setToken();
          }
        }, 100);
      }
      setToken();
      """
    );
  }
  @override
  void initState() {
    super.initState();
  }
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        centerTitle: true,
        title: Text('xxx', style: TextStyle(color: Color(0xff4a4a4a), fontSize: 16, fontWeight: FontWeight.w500)),
        leading: goBackArr(context),
        bottom: PreferredSize(
          preferredSize: Size.fromHeight(2),
          child: Offstage(
            offstage: !isLoading,
            child: SizedBox(
              height: 2,
              width: MediaQuery.of(context).size.width,
              child: LinearProgressIndicator(),
            ),
          ),
        ),
      ),
      body: WebView(
        onWebViewCreated: (WebViewController web) {
          _webViewController = web;
          setState(() {
            isLoading = true;
          });
        },
        onPageFinished: (String value) {
          setState(() {
            isLoading = false;
          });
          setlocalStorage();
        },
        initialUrl: widget.url,
        javascriptMode: JavascriptMode.unrestricted,
      ),
    );
  }
}