SharedPreferences prefs = await SharedPreferences.getInstance();
//下面这句先将对象转变为json字符串,再变为字符串
await prefs.setString("user", jsonEncode(user1));
String abc = prefs.getString("user");
//和上面的顺序相反
Map<String, dynamic> responseJson = json.decode(abc);
Data data = Data.fromJson(responseJson);
print("user3.........." + data.email);