【发布时间】：2019-07-09 04:54:43
【问题描述】：
我正在尝试在 sharedPref 中保存一些数据。但似乎如果对象变大，则 sharedPref 不会保存单个对象。谁能告诉我 Flutter 应用的 sharedPref 的大小限制？
这是转换为 Json 并尝试保存在 sharedPref 中的对象的一部分。许多结构也保留下来。
I/flutter (13111): products: {
I/flutter (13111): product: {
I/flutter (13111): id: 116
I/flutter (13111): metaMerchant: {
I/flutter (13111): id: 3
I/flutter (13111): version: 1
I/flutter (13111): brandDisplayName: Merchant: 2
I/flutter (13111): logoUrls: https://brandmark.io/logo-rank/random/pepsi.png
I/flutter (13111): coverPhotoUrls: https://cdn.pixabay.com/photo/2015/10/12/15/18/store-984393_960_720.jpg
I/flutter (13111): businessTypes: CLOTHS
I/flutter (13111): businessLocation: {
I/flutter (13111): }
I/flutter (13111): businessAddress: {
I/flutter (13111): }
I/flutter (13111): businessSchedule: {
I/flutter (13111): }
I/flutter (13111): isOpenNow: true
I/flutter (13111): deliveryCharge: 20.0
I/flutter (13111): merchantTabs: {
I/flutter (13111): tabId: home
I/flutter (13111): displayName: Home
I/flutter (13111): groupIds: 11
I/flutter (13111): groupIds: 12
I/flutter (13111): groupIds: 13
I/flutter (13111): groupIds: 14
I/flutter (13111): groupIds: 15
I/flutter (13111): }
I/flutter (13111): merchantTabs: {
I/flutter (13111): tabId: home1
I/flutter (13111): displayName: Home1
I/flutter (13111): groupIds: 11
I/flutter (13111): groupIds: 12
I/flutter (13111): groupIds: 13
I/flutter (13111): groupIds: 14
I/flutter (13111): groupIds: 15
I/flutter (13111): }
I/flutter (13111): merchantTabs: {
I/flutter (13111): tabId: home2
I/flutter (13111): displayName: Home2
I/flutter (13111): groupIds: 11
I/flutter (13111): groupIds: 12
I/flutter (13111): groupIds: 13
I/flutter (13111): groupIds: 14
I/flutter (13111): groupIds: 15
I/flutter (13111): }
I/flutter (13111): merchantTabs: {
I/flutter (13111): tabId: home3
I/flutter (13111): displayName: Home3
I/flutter (13111): groupIds: 11
I/flutter (13111): groupIds: 12
I/flutter (13111): groupIds: 13
I/flutter (13111): groupIds: 14
I/flutter (13111): groupIds: 15
I/flutter (13111): }
I/flutter (13111): merchantTabs: {
I/flutter (13111): tabId: home4
I/flutter (13111): displayName: Home4
I/flutter (13111): groupIds: 11
I/flutter (13111): groupIds: 12
I/flutter (13111): groupIds: 13
I/flutter (13111): groupIds: 14
I/flutter (13111): groupIds: 15
I/flutter (13111): }
I/flutter (13111): merchantTabs: {
I/flutter (13111): tabId: home5
I/flutter (13111): displayName: Home5
I/flutter (13111): groupIds: 11
I/flutter (13111): groupIds: 12
I/flutter (13111): groupIds: 13
I/flutter (13111): groupIds: 14
I/flutter (13111): groupIds: 15
I/flutter (13111): }
I/flutter (13111): }
I/flutter (13111): title: Product16
I/flutter (13111): originalPrice: 2962.0
I/flutter (13111): sellingPrice: 2962.0
I/flutter (13111): imageUrls: https://catseye.com.bd/media/catalog/product/cache/1/small_image/1362x1653/85e4522595efc69f496374d01ef2bf13/c/e/ce_panjabi_i14_5e2_623_8_tk_5990_1_.jpg
I/flutter (13111): deliveryCharge: 20.0
I/flutter (13111): productVariation: {
I/flutter (13111): variationEnable: true
I/flutter (13111): extensions: {
I/flutter (13111): id: 44228028569101
I/flutter (13111): title: Extension: 1
I/flutter (13111): merchantId: 3
I/flutter (13111): displayTitle: Extension: 1
I/flutter (13111): description: Extension 1
I/flutter (13111): extensionItems: {
I/flutter (13111): id: 44228028548389
I/flutter (13111): itemTitle: ExtensionItem: 1
I/flutter (13111): extraCharge: 98.0
I/flutter (13111): }
I/flutter (13111): extensionItems: {
I/flutter (13111): id: 44228028557460
I/flutter (13111): itemTitle: ExtensionItem: 2
I/flutter (13111): extraCharge: 42.0
I/flutter (13111): }
I/flutter (13111): extensionItems: {
I/flutter (13111): id: 44228028560873
I/flutter (13111): itemTitle: ExtensionItem: 3
I/flutter (13111): extraCharge: 52.0
I/flutter (13111): }
I/flutter (13111): extensionItems: {
I/flutter (13111): id: 44228028563518
I/flutter (13111): itemTitle: ExtensionItem: 4
I/flutter (13111): extraCharge: 40.0
I/flutter (13111): }
I/flutter (13111): }
I/flutter (13111): extensions: {
I/flutter (13111): id: 44228028605392
I/flutter (13111): title: Extension: 2
I/flutter (13111): merchantId: 3
I/flutter (13111): displayTitle: Extension: 2
I/flutter (13111): description: Extension 2
I/flutter (13111): extensionItems: {
I/flutter (13111): id: 44228028589832
I/flutter (13111): itemTitle: ExtensionItem: 1
I/flutter (13111): extraCharge: 86.0
I/flutter (13111): }
I/flutter (13111): extensionItems: {
I/flutter (13111): id: 44228028593236
I/flutter (13111): itemTitle: ExtensionItem: 2
I/flutter (13111): extraCharge: 57.0
I/flutter (13111): }
I/flutter (13111): extensionItems: {
I/flutter (13111): id: 44228028599177
I/flutter (13111): itemTitle: ExtensionItem: 3
I/flutter (13111): extraCharge: 34.0
I/flutter (13111): }
I/flutter (13111): extensionItems: {
I/flutter (13111): id: 44228028602233
I/flutter (13111): itemTitle: ExtensionItem: 4
I/flutter (13111): extraCharge: 28.0
I/flutter (13111): }
I/flutter (13111): }
I/flutter (13111): itemCombinations: {
I/flutter (13111): indexIds: 0
I/flutter (13111): indexIds: 0
I/flutter (13111): combinationPrice: 4409.0
I/flutter (13111): }
I/flutter (13111): itemCombinations: {
I/flutter (13111): indexIds: 0
I/flutter (13111): indexIds: 1
I/flutter (13111): combinationPrice: 3706.0
I/flutter (13111): }
I/flutter (13111): itemCombinations: {
I/flutter (13111): indexIds: 0
I/flutter (13111): indexIds: 2
I/flutter (13111): combinationPrice: 5198.0
I/flutter (13111): }
I/flutter (13111): itemCombinations: {
I/flutter (13111): indexIds: 0
I/flutter (13111): indexIds: 3
I/flutter (13111): combinationPrice: 1818.0
I/flutter (13111): }
I/flutter (13111): itemCombinations: {
I/flutter (13111): indexIds: 1
I/flutter (13111): indexIds: 0
I/flutter (13111): combinationPrice: 942.0
I/flutter (13111): }
I/flutter (13111): itemCombinations: {
I/flutter (13111): indexIds: 1
I/flutter (13111): indexIds: 1
I/flutter (13111): combinationPrice: 5908.0
I/flutter (13111): }
I/flutter (13111): itemCombinations: {
I/flutter (13111): indexIds: 1
I/flutter (13111): indexIds: 2
I/flutter (13111): combinationPrice: 1542.0
I/flutter (13111): }
I/flutter (13111): itemCombinations: {
I/flutter (13111): indexIds: 1
I/flutter (13111): indexIds: 3
I/flutter (13111): combinationPrice: 6495.0
I/flutter (13111): }
I/flutter (13111): itemCombinations: {
I/flutter (13111): indexIds: 2
I/flutter (13111): indexIds: 0
I/flutter (13111): combinationPrice: 8357.0
I/flutter (13111): }
I/flutter (13111): itemCombinations: {
I/flutter (13111): indexIds: 2
I/flutter (13111): indexIds: 1
I/flutter (13111): combinationPrice: 8865.0
I/flutter (13111): }
I/flutter (13111): itemCombinations: {
I/flutter (13111): indexIds: 2
I/flutter (13111): indexIds: 2
I/flutter (13111): combinationPrice: 3223.0
I/flutter (13111): }
I/flutter (13111): itemCombinations: {
I/flutter (13111): indexIds: 2
I/flutter (13111): indexIds: 3
I/flutter (13111): combinationPrice: 9546.0
I/flutter (13111): }
I/flutter (13111): itemCombinations: {
I/flutter (13111): indexIds: 3
I/flutter (13111): indexIds: 0
I/flutter (13111): combinationPrice: 4137.0
I/flutter (13111): }
I/flutter (13111): itemCombinations: {
I/flutter (13111): indexIds: 3
I/flutter (13111): indexIds: 1
I/flutter (13111): combinationPrice: 5253.0
I/flutter (13111): }
I/flutter (13111): itemCombinations: {
I/flutter (13111): indexIds: 3
I/flutter (13111): indexIds: 2
I/flutter (13111): combinationPrice: 1503.0
I/flutter (13111): }
I/flutter (13111): itemCombinations: {
I/flutter (13111): indexIds: 3
I/flutter (13111): indexIds: 3
I/flutter (13111): combinationPrice: 2174.0
I/flutter (13111): }
I/flutter (13111): }
I/flutter (13111): }
I/flutter (13111): }
这是向 sharedPref 发送数据的代码：
Future<void> saveCarts(Iterable<CartOrderItem> items) async {
try {
final list = items.map((cart) => cart.toJsonMap()).toList();
await Preferences.instance.setJson(CART_LIST_KEY, list);
} catch (err) {
print('<!> [CartRepository] saveCart(): $err');
}
}
这里是sharedPref保存的地方：
import 'dart:async';
import 'dart:convert' show json;
import 'package:shared_preferences/shared_preferences.dart';
export 'package:hurryup/src/strings.dart';
class Preferences {
Future<SharedPreferences> source() {
return SharedPreferences.getInstance();
}
Future<int> getInt(String key) async {
final pref = await source();
return pref.getInt(key);
}
Future<void> setInt(String key, int value) async {
final pref = await source();
final result = await pref.setInt(key, value);
if (!result) {
throw Exception('Could not store integer');
}
}
Future<String> getString(String key) async {
final pref = await source();
return pref.getString(key);
}
Future<void> setString(String key, String value) async {
final pref = await source();
final result = await pref.setString(key, value);
if (!result) {
throw Exception('Could not store string');
}
}
Future<dynamic> getJson(String key) async {
String source = await getString(key);
if (source == null) return null;
return json.decode(source);
}
Future<void> setJson(String key, dynamic jsonData) async {
String value;
if (jsonData != null) {
value = json.encode(jsonData);
}
await setString(key, value);
}
// ----------------------------------------------------------------------- //
static Preferences _instance;
static Preferences get instance => _instance ??= Preferences();
// ----------------------------------------------------------------------- //
}
【问题讨论】：
-
你能告诉我们你要保存什么样的对象吗？
-
用数据结构编辑了我的问题。请评价一下。
-
这不是一个大对象。据我所知，SharedPrefs 不能保存对象，它只能保存基本数据类型，如字符串、整数、布尔值等。我建议您将对象转换为某种 Json 字符串，然后将其保存在首选项中.
-
是的，我这样做并保存了。我再次编辑了我的代码。
-
是的，其实和缓存限制没有关系。我在这里出错了。 cart.toJsonMap()).toList();