path_provider 文件
//创建文件目录函数
/*
* /// 获取文档目录文件
Future _getLocalDocumentFile() async {
final dir = await getApplicationDocumentsDirectory();
return File('${dir.path}/str.txt');
}
/// 获取临时目录文件
Future _getLocalTemporaryFile() async {
final dir = await getTemporaryDirectory();
return File('${dir.path}/str.txt');
}
/// 获取应用程序目录文件
Future _getLocalSupportFile() async {
final dir = await getApplicationSupportDirectory();
return File('${dir.path}/str.txt');
}
*
* */
Future_getLocalFile()async {
print("创建文件");
// 获取应用目录
String dir = (await getApplicationDocumentsDirectory()).path;
return File('$dir/content.txt');
}
//写文件函数
Future_writeFileContent(String content)async {
return (await _getLocalFile()).writeAsString(content);
}
SharedPreferences 键值对信息
// 读取 SharedPreferences 中 key 为 counter 的值
Future_readSPCounter()async {
SharedPreferences prefs =await SharedPreferences.getInstance();
int counter = (prefs.getInt('counter') ??0);
return counter;
}
// 递增写入 SharedPreferences 中 key 为 counter 的值
Future_writeSPCounter()async {
SharedPreferences prefs =await SharedPreferences.getInstance();
int counter = (prefs.getInt('counter') ??0) +1;
prefs.setInt('counter',counter);
}
sqflite 数据库
dependencies:
flutter:
sdk:flutter
sqflite:
1.定义狗数据模型 ---- 2.打开数据库 ---- 3.创建表 ---- 4.插入数据 ---- 5.检索表 ---- 6.更新数据库 ---- 7.删除数据
void PeopleDB()async {
WidgetsFlutterBinding.ensureInitialized();
//打开数据库
final Futuredatabase = openDatabase(
//创建s表
join(await getDatabasesPath(),'peoplegie_database.db'),
onCreate: (db, version) {
return db.execute(
"CREATE TABLE peoples(id INTEGER PRIMARY KEY, name TEXT, age INTEGER)",
);
},
version:1,
);
//插入数据
FutureinsertPeople(People peopl)async {
final Database db =await database;
await db.insert(
'peoples',
peopl.toMap(),
conflictAlgorithm:ConflictAlgorithm.replace,
);
}
//检索列表
Future>peoples()async {
final Database db =await database;
final List>maps =await db.query('peoples');
return List.generate(maps.length, (i) {
return People(
id:maps[i]['id'],
name:maps[i]['name'],
age:maps[i]['age'],
);
});
}
//更新数据
FutureupdatePeople(People people)async {
final db =await database;
await db.update(
'peoples',
people.toMap(),
where:"id = ?",
whereArgs: [people.id],
);
}
//删除数据
FuturedeletePeople(int id)async {
final db =await database;
await db.delete(
'Peoples',
where:"id = ?",
whereArgs: [id],
);
}
var fido =People(
id:0,
name:'Fido',
age:35,
);
await insertPeople(fido);
print(await peoples());
fido =People(
id:fido.id,
name:fido.name,
age:fido.age +7,
);
await updatePeople(fido);
print(await peoples());
await deletePeople(fido.id);
print(await peoples());
}
class People {
final int id;
final String name;
final int age;
People({required this.id,required this.name,required this.age});
MaptoMap() {
return {
'id':id,
'name':name,
'age':age,
};
}
@override
String toString() {
return 'People{id: $id, name: $name, age: $age}';
}
}
