flutter开发：sqlflite的使用（完整demo）

引入插件

dependencies:
  flutter:
    sdk: flutter
  cupertino_icons: ^0.1.2
  sqflite: ^1.1.7+3

封装公共方法

这里的两个公共类是封装的比较好的，只要有sqlflite数据库操作就可以拿过来直接用的

1. 数据库初始化，获取数据库对象以及关闭数据库。在sqflite中的数据库操作，首先得获取到数据库对象，通过数据库对象才可以对相应的表进行增删查改。

import 'package:sqflite/sqflite.dart';

import 'package:path/path.dart';

class SqlManager{

static const _VERSION=1;

static const _NAME="my.db";

static Database _database;


///初始化
static init() async {

  var databasesPath=await getDatabasesPath();
  String path = join(databasesPath, _NAME);
  _database=await openDatabase(path,version: _VERSION,onCreate: (Database db,int version) async{});
}

///判断表是否存在
static isTableExits(String tableName) async {
  await getCurrentDatabase();
  var res=await _database.rawQuery("select * from Sqlite_master where type = 'table' and name = '$tableName'");
  return res!=null && res.length >0;
}

///获取当前数据库对象
static Future<Database> getCurrentDatabase() async {
  if(_database == null){
    await init();
  }
  return _database;
}

///关闭
static close() {
  _database?.close();
  _database = null;
}
}

2. 在对某一张表进行操作时，先得判断数据库对象是否存在，不存在就得创建。再判断表是否在该数据库中存在，不存在就创建。

import 'package:flutter_database/database/sql_manager.dart';
import 'package:sqflite/sqflite.dart';
import 'package:meta/meta.dart';

abstract class BaseDbProvider {
  bool isTableExits = false;

  createTableString();

  tableName();

  ///创建表sql语句
  tableBaseString(String sql) {
    return sql;
  }

  Future<Database> getDataBase() async {
    return await open();
  }

  ///super 函数对父类进行初始化
  @mustCallSuper
  prepare(name, String createSql) async {
    isTableExits = await SqlManager.isTableExits(name);
    if (!isTableExits) {
      Database db = await SqlManager.getCurrentDatabase();
      return await db.execute(createSql);
    }
  }

  @mustCallSuper
  open() async {
    if (!isTableExits) {
      await prepare(tableName(), createTableString());
    }
    return await SqlManager.getCurrentDatabase();
  }
}

具体操作

1. 新建bean类,这里除了基本的get和set方法之外还有User对象转map，map转User的两个方法。

class User {
  User();

  int _id;
  String _name;
  String _desc;

  int get id => _id;

  String get name => _name;

  String get desc => _desc;

  set desc(String value) {
    _desc = value;
  }

  set name(String value) {
    _name = value;
  }

  set id(int value) {
    _id = value;
  }

  Map<String, dynamic> toMap() {
    var map = Map<String, dynamic>();

    map['id'] = _id;
    map['name'] = _name;
    map['desc'] = _desc;

    return map;
  }

  User.fromMapObject(Map<String, dynamic> map) {
    this._id = map['id'];
    this._name = map['name'];
    this._desc = map['desc'];
  }
}

2. User表的增删查改方法

import 'package:sqflite/sqlite_api.dart';

import 'package:flutter_database/database/base_provider.dart';
import 'package:flutter_database/database/user.dart';

class UserDbProvider extends BaseDbProvider {
  ///表名
  final String name = 'UserInfo';

  final String columnId = "id";
  final String columnName = "name";
  final String columnDesc = "desc";

  UserDbProvider();

  //获取表名称
  @override
  tableName() {
    return name;
  }

  //创建表操作
  @override
  createTableString() {
    return '''
        create table $name (
        $columnId integer primary key,$columnName text not null,
        $columnDesc text not null)
      ''';
  }

  ///查询数据
  Future selectUser(int id) async {
    Database db = await getDataBase();
    return await db.rawQuery("select * from $name where $columnId = $id");
  }

  //查询数据库所有
  Future<List<Map<String, dynamic>>> selectMapList() async {
    var db = await getDataBase();
    var result = await db.query(name);
    return result;
  }

  //获取数据库里所有user
  Future<List<User>> getAllUser() async{
    var userMapList = await selectMapList();
    var count  = userMapList.length;
    List<User> userList= List<User>();

    for(int i=0;i<count;i++){
      userList.add(User.fromMapObject(userMapList[i]));
    }
    return userList;
  }

  //根据id查询user
  Future<User> getUser(int id) async {
    var noteMapList = await selectUser(id); // Get 'Map List' from database
    var user = User.fromMapObject(noteMapList[id]);
    return user;
  }

  //增加数据
  Future<int> insertUser(User user) async {
    var db = await getDataBase();
    var result = await db.insert(name, user.toMap());
    return result;
  }

  //更新数据
  Future<int> update(User user) async {
    var database = await getDataBase();
    var result = await database.rawUpdate(
        "update $name set $columnName = ?,$columnDesc = ? where $columnId= ?",
        [user.name, user.desc, user.id]);
    return result;
  }

  //删除数据
  Future<int> deleteUser(int id) async {
    var db = await getDataBase();
    var result = await db.rawDelete('DELETE FROM $name WHERE $columnId = $id');
    return result;
  }
}

外部使用

1. 创建Provider对象。

 UserDbProvider provider = UserDbProvider();

2.通过对象调用User的增删查改方法

 if (user.id == null) {
     user.id = new DateTime.now().millisecondsSinceEpoch;  //id 为当前时间戳
     result = await provider.insertUser(user);
   } else {
     result = await provider.update(user);
   }

完整demo

去github上查看demo