如何在build方法flutter中访问共享首选项字符串

dependencies:
  shared_preferences: ^2.0.8

import 'package:shared_preferences/shared_preferences.dart';

Future<String> getSharedPreferenceString() async {
  SharedPreferences prefs = await SharedPreferences.getInstance();
  String stringValue = prefs.getString('key');
  return stringValue;
}

@override
Widget build(BuildContext context) {
  return FutureBuilder<String>(
    future: getSharedPreferenceString(),
    builder: (BuildContext context, AsyncSnapshot<String> snapshot) {
      if (snapshot.hasData) {
        String sharedPreferenceString = snapshot.data;
        // 使用共享首选项字符串进行构建
        return Text(sharedPreferenceString);
      } else {
        // 加载中或出错时的处理
        return CircularProgressIndicator();
      }
    },
  );
}