如何使用存储在 FutureBuilder 的 snapshot.data 中的 JSON 数据(不带类)？

Question

return loading ? Loading() : FutureBuilder(
future: SaadConstants.getJsonLanguagePack(),// edit pls
builder: (BuildContext context, AsyncSnapshot snapshot)
{
if (snapshot.connectionState == ConnectionState.waiting) {
return Center(child: CircularProgressIndicator());
}
// rest of code

My getJsonLanguagePack((：

static Future<String > getJsonLanguagePack() async {
SharedPreferences pref = await SharedPreferences.getInstance();
return json.decode(pref.getString('languagePack')); // languagePack Exists as String already locally containing all the json file content (local json file)
}

我的 JSON 文件 ：

[
{"key":"registerNew", "value":"Nouveau ?" },
{"key":"emailPlaceHolder", "value":"Entrez votre email." },
{"key":"passwordPlaceHolder", "value":"Entrez votre mot de pass." },
{"key":"rememberMe", "value":"rester connecté." },
{"key":"forgotPass", "value":"Pass oublié ?" },
{"key":"loginBtn", "value":"Connexion" },
{"key":"_or_", "value":"_OU_" }]

我试图在我的getJsonLanguagePack上返回Future> 但它在 FutureBuilder 中引发了一个错误，说字符串不是 Map 的子类型

问题是当我尝试访问快照数据时。我无法使用在 JSON 文件中定义的键来获取所需的值。

因为它被调和为字符数组。

多谢。

Answer 1

您不必将 json 文件数据复制到SharePreference中。您可以直接使用它们

import 'dart:convert';
import "package:flutter/material.dart";
import 'package:flutter/services.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
Widget build(BuildContext context) {
return MaterialApp(
home: HomePage(),
);
}
}
class HomePage extends StatelessWidget {
static Future<Map<String, String>> loadJsonLanguage(String langName) async {
final jsonString = await rootBundle
.loadString('assets/app_languages/' + langName + '.json');
List translationList = jsonDecode(jsonString);
final mappedTranslation = <String, String>{};
translationList.forEach((dynamic item) {
mappedTranslation[item["key"]] = item["value"];
});
return mappedTranslation;
}
@override
Widget build(BuildContext context) {
return Scaffold(
body: FutureBuilder(
future: loadJsonLanguage("ar"),
builder: (context, snapshot) {
if (snapshot.connectionState == ConnectionState.waiting)
return Center(child: CircularProgressIndicator());
else if (snapshot.hasError)
return Center(child: Text("${snapshot.error}"));
return Center(child: Text(snapshot.data["registerNew"]));
},
),
);
}
}