Flutter数据存储之sqflite的使用

2023年8月15日 407次阅读 来源: 我感觉很难受

1.首先需要导入在pubspec.yaml中导入sqflite

1）dependencies:

sqflite: ^1.0.0

https://pub.dartlang.org/packages/sqflite

2）执行   flutter packages get

3）导入      import ‘package:sqflite/sqflite.dart’;

2.为了保证对数据库操作的过程中不会创建多个实例，所以工具类需要使用单例模式

主要用到的是DatabaseHelper，数据库的增删查改和sqlite没区别，直接贴出代码块

注：其中使用到的Note.dart

class Note {
  int _id;
  int _pointid;
  String _image;
  int _contractId;
  int _publicationId;
  double _pointLng;
  double _pointLat;

  Note(this._pointid, this._image ,this._contractId,this._publicationId,this._pointLng,this._pointLat);

  Note.map(dynamic obj) {
    this._id = obj['id'];
    this._pointid = obj['pointid'];
    this._image = obj['image'];
    this._contractId = obj['contractId'];
    this._publicationId = obj['publicationId'];
    this._pointLng = obj['pointLng'];
    this._pointLat = obj['pointLat'];
  }

  int get id => _id;
  int get pointid => _pointid;
  String get image => _image;
  int get contractId => _contractId;
  int get publicationId => _publicationId;
  double get pointLng => _pointLng;
  double get pointLat => _pointLat;

  Map<String, dynamic> toMap() {
    var map = new Map<String, dynamic>();
    if (_id != null) {
      map['id'] = _id;
    }
    map['pointid'] = _pointid;
    map['image'] = _image;
    map['contractId'] = _contractId;
    map['publicationId'] = _publicationId;
    map['pointLng'] = _pointLng;
    map['pointLat'] = _pointLat;
    return map;
  }

  Note.fromMap(Map<String, dynamic> map) {
    this._id = map['id'];
    this._pointid = map['pointid'];
    this._image = map['image'];
    this._contractId = map['contractId'];
    this._pointLng = map['pointLng'];
    this._pointLat = map['pointLat'];
  }
}

1）创建数据库

  void _onCreate(Database db, int newVersion) async {
    await db.execute(
        'CREATE TABLE $tableNote($columnId INTEGER PRIMARY KEY AUTOINCREMENT, $pointid TEXT, $image TEXT, $contractId TEXT, $publicationId TEXT, $pointLng TEXT, $pointLat TEXT)');
  }

2）增加一条数据

Future<int> saveNote(Note note) async {
    var dbClient = await db;
    var result = await dbClient.insert(tableNote, note.toMap());
//    var result = await dbClient.rawInsert(
//        'INSERT INTO $tableNote ($columnTitle, $columnDescription) VALUES (\'${note.title}\', \'${note.description}\')');

    return result;
  }

3）获取数据库所有的数据

  Future<List> getAllNotes() async {
    var dbClient = await db;
    var result = await dbClient.query(tableNote, columns: [columnId, pointid, image, contractId ,publicationId, pointLng, pointLat]);
    return result.toList();
  }

4）获取数据库数据的数量

  Future<int> getCount() async {
    var dbClient = await db;
    return Sqflite.firstIntValue(await dbClient.rawQuery('SELECT COUNT(*) FROM $tableNote'));
  }

5）获取数据库其中一条数据（键是id）

  Future<Note> getNote(int id) async {
    var dbClient = await db;
    List<Map> result = await dbClient.query(tableNote,
        columns: [columnId, pointid, image ,contractId, publicationId, pointLng, pointLat],
        where: '$columnId = ?',
        whereArgs: [id]);
//    var result = await dbClient.rawQuery('SELECT * FROM $tableNote WHERE $columnId = $id');

    if (result.length > 0) {
      return new Note.fromMap(result.first);
    }

    return null;
  }

6）删除数据库一条数据

  Future<int> deleteNote(String images) async {
    var dbClient = await db;
    return await dbClient.delete(tableNote, where: '$image = ?', whereArgs: [images]);
//    return await dbClient.rawDelete('DELETE FROM $tableNote WHERE $columnId = $id');
  }

7）更改数据库一条数据

  Future<int> updateNote(Note note) async {
    var dbClient = await db;
    return await dbClient.update(tableNote, note.toMap(), where: "$columnId = ?", whereArgs: [note.id]);
//    return await dbClient.rawUpdate(
//        'UPDATE $tableNote SET $columnTitle = \'${note.title}\', $columnDescription = \'${note.description}\' WHERE $columnId = ${note.id}');
  }

8）关闭数据库

  Future close() async {
    var dbClient = await db;
    return dbClient.close();
  }

最后贴出代码块的集合

import 'dart:async';

import 'package:sqflite/sqflite.dart';
import 'package:path/path.dart';
import 'package:seller_app/model/Note.dart';

class DatabaseHelper {
  static final DatabaseHelper _instance = new DatabaseHelper.internal();

  factory DatabaseHelper() => _instance;

  final String tableNote = 'note11Table';
  final String columnId = 'id';
  final String pointid = 'pointid';
  final String image = 'image';
  final String contractId = 'contractId';
  final String publicationId = 'publicationId';
  final String pointLat = 'pointLat';
  final String pointLng = 'pointLng';

  static Database _db;

  DatabaseHelper.internal();

  Future<Database> get db async {
    if (_db != null) {
      return _db;
    }
    _db = await initDb();

    return _db;
  }

  initDb() async {
    String databasesPath = await getDatabasesPath();
    String path = join(databasesPath, 'notes11.db');

//    await deleteDatabase(path); // just for testing

    var db = await openDatabase(path, version: 1, onCreate: _onCreate);
    return db;
  }

  void _onCreate(Database db, int newVersion) async {
    await db.execute(
        'CREATE TABLE $tableNote($columnId INTEGER PRIMARY KEY AUTOINCREMENT, $pointid TEXT, $image TEXT, $contractId TEXT, $publicationId TEXT, $pointLng TEXT, $pointLat TEXT)');
  }

  Future<int> saveNote(Note note) async {
    var dbClient = await db;
    var result = await dbClient.insert(tableNote, note.toMap());
//    var result = await dbClient.rawInsert(
//        'INSERT INTO $tableNote ($columnTitle, $columnDescription) VALUES (\'${note.title}\', \'${note.description}\')');

    return result;
  }

  Future<List> getAllNotes() async {
    var dbClient = await db;
    var result = await dbClient.query(tableNote, columns: [columnId, pointid, image, contractId ,publicationId, pointLng, pointLat]);
//    var result = await dbClient.rawQuery('SELECT * FROM $tableNote');

    return result.toList();
  }

  Future<int> getCount() async {
    var dbClient = await db;
    return Sqflite.firstIntValue(await dbClient.rawQuery('SELECT COUNT(*) FROM $tableNote'));
  }

  Future<Note> getNote(int id) async {
    var dbClient = await db;
    List<Map> result = await dbClient.query(tableNote,
        columns: [columnId, pointid, image ,contractId, publicationId, pointLng, pointLat],
        where: '$columnId = ?',
        whereArgs: [id]);
//    var result = await dbClient.rawQuery('SELECT * FROM $tableNote WHERE $columnId = $id');

    if (result.length > 0) {
      return new Note.fromMap(result.first);
    }

    return null;
  }

  Future<int> deleteNote(String images) async {
    var dbClient = await db;
    return await dbClient.delete(tableNote, where: '$image = ?', whereArgs: [images]);
//    return await dbClient.rawDelete('DELETE FROM $tableNote WHERE $columnId = $id');
  }

  Future<int> updateNote(Note note) async {
    var dbClient = await db;
    return await dbClient.update(tableNote, note.toMap(), where: "$columnId = ?", whereArgs: [note.id]);
//    return await dbClient.rawUpdate(
//        'UPDATE $tableNote SET $columnTitle = \'${note.title}\', $columnDescription = \'${note.description}\' WHERE $columnId = ${note.id}');
  }

  Future close() async {
    var dbClient = await db;
    return dbClient.close();
  }
}

3.使用

1）导入工具类 例：

import 'package:seller_app/systemAssembly/DatabaseHelper.dart';

2）创建

var db = new DatabaseHelper();

3）

创建数据：

await db.saveNote(new Note(pointId, _image,contractId,publicationId,locationLng,locationLat));

获取所有的数据：

  List notes;
  print('=== getAllNotes() ===');
  notes = await db.getAllNotes();
  notes.forEach((note) => print(note));

删除某一条数据：

db.deleteNote(image); //image为数据库中某一条数据的image属性

好了，到这里就结束了。欢迎大家一起探讨flutter，有什么不明白的可以留言。本人也是flutter小白一枚，正在踩坑，文章逻辑也比较乱，将就看看吧，谢谢大家^_^

    原文作者：我感觉很难受
    原文地址: https://blog.csdn.net/zz1667654468/article/details/86626863
    本文转自网络文章，转载此文章仅为分享知识，如有侵权，请联系博主进行删除。
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