Flutter-数据持久化（shared_preferences、sqflite）

shared_preferences

示例

static Future<void> setToken(String token) async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    await prefs.setString(TOKEN, token);
}

static Future<String?> getToken() async {
   SharedPreferences prefs = await SharedPreferences.getInstance();
   if (await prefs.containsKey(TOKEN)) {
      var json = await prefs.getString(TOKEN);
      return json;
   } else {
      return null;
  }
}

String? toeken = await DTWRoleManager.getToken();

相关方法

SharedPreferences prefs = await SharedPreferences.getInstance();
prefs.setString(key, value)
prefs.setBool(key, value)
prefs.setDouble(key, value)
prefs.setInt(key, value)
prefs.setStringList(key, value)
prefs.remove(key)
prefs.clear()

sqflite

打开数据库（可同时新建或更新表）

  DTWDBHandle.internal();
  //数据库句柄
  static Database? _database;
  Future<Database?> get database async {
    if (_database == null) {
      var databasesPath = await getDatabasesPath();
      String path = join(databasesPath, DB_NAME_DTW);
      _database =
          await openDatabase(path, version: DB_VERSION, onCreate: _onCreate);
    }
    print(_database!.path.toString());
    return _database;
  }

  //创建表
  void _onCreate(Database db, int version) async {
    final sql = '''
      create table if not exists $DB_TABLE_SET (
      account text,
      pid text
    ''';
    var batch = db.batch();
    batch.execute(sql);
    await batch.commit();
  }

  //打开
  Future<Database?> open() async {
    return await database;
  }

插入

Database? db = await DTWDBHandle.internal().open();
await db!.insert(DB_TABLE_SET, setData.toJson());
await db.batch().commit();

修改

 Database? db = await DTWDBHandle.internal().open();
 String sqlWhere = '''
        account='${setData.account}' and
        pid='${setData.pid}' 
        ''';
 db!.update(DB_TABLE_SET, setData.toJson(), where: sqlWhere);
 await db.batch().commit();

删除

Database? db = await DTWDBHandle.internal().open();
String sql = '''
        delete from $DB_TABLE_SET where 
        account='${setData.account}' and
        pid='${setData.pid}'
        ''';
db!.rawDelete(sql);
await db.batch().commit();

查询

Database? db = await DTWDBHandle.internal().open();
String sql = '''select * from $DB_TABLE_SET''';
List<Map<String, dynamic>> maps = await db!.rawQuery(sql);