Flutter 本地固化之 SharedPreferences 封装
直接上代码了
(如果有写的不完善的地方,欢迎指正)
新的改动
#重新调整了下, 这里吧几个基础方法变为内部静态函数, 不对外提供
#提供以key 为函数名的静态方法,指定枚举类型来供外部使用
/// *********************************** SharePreferencesUtils 静态私有方法 ***********************************
///
///
/// 存/更 - 进行json序列化, 均为json字符串形式保存
/// 成功返回 Future 的成功态
/// 失败 抛出异常信息
static Future<dynamic> _saveToLocalMap(String key, dynamic value) async {
final com = Completer();
final future = com.future;
try {
SharedPreferences prefs = await SharedPreferences.getInstance();
String jsonEncodestr = jsonEncode(value);
prefs.setString(key, jsonEncodestr);
com.complete(true);
print('======= json序列化的待存储字符串 ======== : ' + jsonEncodestr);
print(' save is ok ,,,,,');
} catch (err) {
com.complete(false);
print(' save is err ,,,,,');
print(err.toString());
}
return future;
}
/// 删 - 根据key 删除对应的数据
/// 成功返回 Future 的成功态
/// 失败 抛出异常信息
static Future<dynamic> _deleteFromLocalMap(String key) async {
final com = Completer();
final future = com.future;
try {
SharedPreferences prefs = await SharedPreferences.getInstance();
prefs.remove(key);
com.complete(true);
print(' delete is ok ,,,,,');
} catch (err) {
com.complete(false);
print(' delete is err ,,,,,');
print(err.toString());
}
return future;
}
/// 取 - 读取key 对应的json序列化字符串,并进行反序列化
/// 成功返回 Future 的成功对象
/// 失败 抛出异常信息
static Future<dynamic> _readFromLocalMap(String key) async {
final com = Completer();
final future = com.future;
try {
SharedPreferences prefs = await SharedPreferences.getInstance();
final values = prefs.get(key);
var obj = jsonDecode(values);
com.complete(obj);
print('======= json反序列化后的dynamic对象 ======== : ' + obj.toString());
print(' read is ok ,,,,,');
} catch (err) {
// 读取失败, 仅返回一个null, 防止外部不catch,引起报错, 但是外部就需要做好判空
com.complete(null);
print(' read is err ,,,,,');
}
return future;
}
/// *********************************** SharePreferencesUtils 静态方法 ***********************************
/// 存取删tokey
/// [SharePreferencesUtilsWorkType] 指定操作模式
static token(SharePreferencesUtilsWorkType type, {dynamic value}) {
String key = 'token';
if (type == SharePreferencesUtilsWorkType.save) {
return _saveToLocalMap(key, value);
}
if (type == SharePreferencesUtilsWorkType.remove) {
return _deleteFromLocalMap(key);
}
if (type == SharePreferencesUtilsWorkType.get) {
return _readFromLocalMap(key);
}
}
使用
// 请求前, 获取一下token塞进报文headers
var token = await SharePreferencesUtils.token(SharePreferencesUtilsWorkType.get);
bool saveScuess = await SharePreferencesUtils.token(SharePreferencesUtilsWorkType.save, value: token);
saveScuess ? debugPrint('token 保存成功') : debugPrint('token 保存失败');
========= 旧的内容 =======
import 'dart:async';
/// -------------------------------
/// Created with Flutter Dart File.
/// User [email protected]
/// Date: 2020-08-17
/// Time: 13:44
/// Des: 类似于 iOS的NSUserDefaults和Android的SharedPreferences 轻量级存储类
/// -------------------------------
import 'package:shared_preferences/shared_preferences.dart';
import 'dart:convert';
class SharePreferencesUtils {
/// 存/更 - 进行json序列化, 均为json字符串形式保存
/// 成功返回 Future 的成功态
/// 失败 抛出异常信息
static Future<dynamic> saveToLocalMap(String key, dynamic value) async {
final com = Completer();
final future = com.future;
try {
SharedPreferences prefs = await SharedPreferences.getInstance();
String jsonEncodestr = jsonEncode(value);
prefs.setString(key, jsonEncodestr);
com.complete(true);
print('======= json序列化的待存储字符串 ======== : ' + jsonEncodestr);
print(' save is ok ,,,,,');
} catch (err) {
com.complete(false);
print(' save is err ,,,,,');
print(err.toString());
}
return future;
}
/// 删 - 根据key 删除对应的数据
/// 成功返回 Future 的成功态
/// 失败 抛出异常信息
static Future<dynamic> deleteFromLocalMap(String key) async {
final com = Completer();
final future = com.future;
try {
SharedPreferences prefs = await SharedPreferences.getInstance();
prefs.remove(key);
com.complete(true);
print(' delete is ok ,,,,,');
} catch (err) {
com.complete(false);
print(' delete is err ,,,,,');
print(err.toString());
}
return future;
}
/// 取 - 读取key 对应的json序列化字符串,并进行反序列化
/// 成功返回 Future 的成功对象
/// 失败 抛出异常信息
static Future<dynamic> readFromLocalMap(String key) async {
final com = Completer();
final future = com.future;
try {
SharedPreferences prefs = await SharedPreferences.getInstance();
final values = prefs.get(key);
var obj = jsonDecode(values);
com.complete(obj);
print('======= json反序列化后的dynamic对象 ======== : ' + obj.toString());
print(' read is ok ,,,,,');
} catch (err) {
// 读取失败, 仅返回一个null, 防止外部不catch,引起报错, 但是外部就需要做好判空
com.complete(null);
print(' read is err ,,,,,');
}
return future;
}
}
使用
/// *********************************** fun ***********************************
_onTap(BuildContext ctx, int index) async {
switch (index) {
case 1:
{
var saveScuess = await SharePreferencesUtils.saveToLocalMap('name', {
'111': [1, 33, 3, "ddf"]
});
print(saveScuess);
}
break;
case 2:
{
var removeSuc = await SharePreferencesUtils.readFromLocalMap('name');
print(removeSuc);
}
break;
case 3:
{
var res = await SharePreferencesUtils.deleteFromLocalMap('name');
print(res.toString());
}
break;
}
}
log
I/flutter (19053): ======= json序列化的待存储字符串 ======== : {"111":[1,33,3,"ddf"]}
I/flutter (19053): save is ok ,,,,,
I/flutter (19053): true
I/flutter (19053): ======= json反序列化后的dynamic对象 ======== : {111: [1, 33, 3, ddf]}
I/flutter (19053): read is ok ,,,,,
I/flutter (19053): {111: [1, 33, 3, ddf]}
I/flutter (19053): delete is ok ,,,,,
I/flutter (19053): true