Flutter SQLHelpers Demo

创建 model

final String tableUser='user';
final String columnId='_id';
final String columnName='name';

class User{
  int id;
  String name;

  /***
   * 将类转换为键值对
   */
  Map<String,dynamic> toMap(){
    var map=<String,dynamic>{
      columnName:name,
    };
    if(id!=null){
      map[columnId]=id;
    }
    return map;
  }
  
  User();

  /***
   * 将键值对转换为类
   */
  User.fromMap(Map<String,dynamic> map){
    id=map[columnId];
    name=map[columnName];
  }
}

创建SQLHelper

class DBProvider{
  DBProvider._();
  static final DBProvider db=DBProvider._();
  Database _database;
  
  Future<Database> get database async{
    if(_database!=null){
      return _database;
    }
    _database=await initDB();
    return _database;
  }
  
  initDB() async{
    Directory documentsDirectory=await getApplicationDocumentsDirectory();
    String path=join(documentsDirectory.path,'UserDB.db');
    return await openDatabase(path,version: 1,onOpen: (db){},onCreate: (Database db,int version)async{
      await db.execute('''
      create table $tableUser(
      $columnId integer primary key autoincrement,
      $columnName text not null)
      ''');
    });
  }
  
  Future<User> insert(User user) async{
    final db=await database;
    user.id=await db.insert(tableUser, user.toMap());
    return user;
  }
  
  Future<User> getUser(int id) async{
    final db=await database;
    List<Map> maps=await db.query(tableNew,columns: [columnId,columnName],
    where: '$columnId=?',
    whereArgs: [id]);
    if(maps.length>0){
      return User.fromMap(maps.first);
    }
    return null;
  }
  
  Future<List<User>> getAllUser() async{
    final db=await database;
    var res=await db.query("User");
    List<User> list=res.isNotEmpty?res.map((c)=>User.fromMap(c)).toList():[];
    return list;
  }
  
  Future<int> delete(int id) async{
    final db=await database;
    return await db.delete(tableUser,where: '$columnId=?',whereArgs: [id]);
  }
  
  Future<int> update(User user)async{
    final db=await database;
    return await db.update(tableUser, user.toMap(),where: '$columnId=?',whereArgs: [user.id]);
  }
  
  removeAll() async{
    final db=await database;
    db.delete(tableUser);
  }

  Future close() async{
    final db=await database;
    db.close();
  }
}

界面

class _MyHomePageState extends State<MyHomePage> {

  final TextEditingController textEditingController=new TextEditingController();

  _saveData(){
    User user=User();
    user.name=textEditingController.text;
    DBProvider.db.insert(user);
    Navigator.of(context).push(
      new MaterialPageRoute(builder: (context){
        return new PageResult();
      })
    );
  }

  _removeData(){
    DBProvider.db.removeAll();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          children: <Widget>[
            TextField(
              controller: textEditingController,
              autofocus: true,
              decoration: new InputDecoration(hintText: '请输入打卡姓名'),
            ),
            RaisedButton(
              child: Text('保存'),
              onPressed: _saveData,
            ),
            RaisedButton(
              child: Text('清除数据'),
              onPressed: _removeData,
            ),
          ],
        ),
      ),
    );
  }
}