如何在flutter中缓存未来的字符串

dependencies:
  shared_preferences: ^2.0.8

import 'package:shared_preferences/shared_preferences.dart';

Future<void> cacheString(String key, String value) async {
  SharedPreferences prefs = await SharedPreferences.getInstance();
  await prefs.setString(key, value);
}

Future<String?> getCachedString(String key) async {
  SharedPreferences prefs = await SharedPreferences.getInstance();
  return prefs.getString(key);
}

Future<void> clearCachedString(String key) async {
  SharedPreferences prefs = await SharedPreferences.getInstance();
  await prefs.remove(key);
}