我一直在使用shared_preferences创建和写入Json Files。我面临的问题是我不知道如何在shared_preferences中创建一个Json数组和一个列表。
我想保存并阅读Json List。
read(String key) async {
final prefs = await SharedPreferences.getInstance();
return json.decode(prefs.getString(key));
}
save(String key, value) async {
final prefs = await SharedPreferences.getInstance();
prefs.setString(key, json.encode(value));
}
remove(String key) async {
final prefs = await SharedPreferences.getInstance();
prefs.remove(key);
}
} ```
最佳答案
DartPad的示例。
Save a list to SharedPreferences with
setStringList
:
const String key = "users";
List<User> users = [User(name: "tester")];
List<String> jsonList = users.map((user) => user.toJson()).toList();
SharedPreferences prefs = await SharedPreferences.getInstance();
prefs.setStringList(key, jsonList);
Read a list from SharedPreferences with
getStringList
:
jsonList = prefs.getStringList(key);
users = jsonList.map((json) => User.fromJson(json)).toList();
The user class with json convert: JSON and serialization
class User {
String name;
int age;
User({
this.name,
this.age,
});
factory User.fromJson(String str) => User.fromMap(json.decode(str));
String toJson() => json.encode(toMap());
factory User.fromMap(Map<String, dynamic> json) => User(
name: json["name"],
age: json["age"],
);
Map<String, dynamic> toMap() => {
"name": name,
"age": age,
};
}
关于flutter - 创建Json数组并使用SharedPreferences列出,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/60192099/