IT博客汇 | WP8.1开发:MVVM记事本-SQLite存储

WP8.1开发:MVVM记事本-SQLite存储

编程小梦发表于 2014-10-19 12:33:03

(正式开篇之前,先吐槽几句.小梦这周运气挺背的:

首先是网站在12号晚莫名崩溃.从晚上8点一直搞到凌晨2点才搞定.这真是一行代码引发的血案,查找到原因后真心无比郁闷!
其次是<随机信号分析>突然宣布平时要多加俩次考试,考试不过也直接挂科.再加上之前我们副院长带的双语课(英文课本,英文作业,英文课件,英文考试,就是讲课用下汉语)<数字信号处理>同样要多考俩次,本没有期中考试的大三就多了俩门考试.你说都在期末一次搞定是多么好啊.
最后就是周五莫名发烧39.4.今天才差不多恢复!所以大家一定要多多锻炼身体哦!)

小梦的感悟就是意外随时有可能降临,所以其实我们现在正常的学习,生活,工作已是一种幸福.我们应该去珍惜我们现在所拥有的一切,对于身边的人,事,物.我们应常怀感恩之心去对待他们.或许,明天,这一切都没有了呢?!不要以为你所拥有或得到的一切是理所应当的.

下面我们正式开始,我们实现的是一个可以增删改查的记事本应用.有了这个基础,大家可以根据我前面介绍的图片选取保存,录音,Onedrive备份,人人网,新浪微博第三方分享等再进行扩展,这些我之前都讲过.

首先我们需要安装SQLite数据库:

请参考:

记事本的service:

Service就是实现对记事的增加,删除,更新,查找所有记事,查找指定ID记事.同时我们使用了单例模式.

所谓单例模式就是:保证一个类仅有一个实例,并提供一个它的全局访问点.完整代码如下:

using Note.Model;
using SQLite;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Windows.Storage;
using Windows.UI.Popups;

namespace Note.Service
{
   public  class DataService
    {

       private static DataService _dataService;//单例模式()

       public static DataService Current
       {
           get
           {
               if (_dataService == null)
               {
                   _dataService = new DataService();
               }
               return _dataService;
           }
       }

       private DataService()
       {

       }

       public static SQLiteAsyncConnection GetConn()//获取数据库
       {
           return new SQLiteAsyncConnection(ApplicationData.Current.LocalFolder.Path + "\\note.db");
       }

      public async void Add(Notes note)//增加记事
       {
           SQLiteAsyncConnection conn = GetConn();
           await conn.InsertAsync(note);
       }

       public async void Delete(int id)//删除记事
       {
           SQLiteAsyncConnection conn = GetConn();
           var query = from note in conn.Table()
                       where note.ID == id
                       select note;
           Notes notes = await query.FirstOrDefaultAsync();
           await conn.DeleteAsync(notes);
       }

       public async void  Modify(Notes notedemo)//更新记事
       {
           SQLiteAsyncConnection conn = GetConn();
           await conn.UpdateAsync(notedemo); 
       }

       public async Task Query(int id)//按ID查找记事
       {
           SQLiteAsyncConnection conn = GetConn();
           var query = from note in conn.Table()
                               where note.ID == id
                               select note;
           Notes notes = await query.FirstOrDefaultAsync();
           return notes;
       }

       public  async Task> Query()//查找所有记事
       {
           SQLiteAsyncConnection conn = GetConn();

           var query = conn.Table();

           List result = await query.ToListAsync();
           return result;

       }
   }
}

记事本的Model:

Model就是对记事本数据的抽象.代码如下:

using SQLite;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Note.Model
{
    public class Notes:ModelBase
    {

        private int id;
        [AutoIncrement, PrimaryKey] //主键并且自增
        public int ID
        {
            get;
            set;
        }

        private string name;
        [MaxLength(1000)]
        public string Name
        {
            get { return name; }
            set
            { this.SetProperty(ref this.name, value); }
        }

        private string content;
        [MaxLength(3000)]
        public string Content
        {
            get { return content; }
            set
            { this.SetProperty(ref this.content,value); }
        }
    }
}

ModelBase类就是对INotifyPropertyChanged接口的具体实现,前面已经说过多次,这次就不贴代码了.

记事本的View:

一个最简单的记事本应用,我们至少需要俩个页面.一个用来显示所有记事,一个用来增加,修改记事.

记事列表页:

我们使用了MenuFlyout控件,不熟悉的朋友可以参考MSDN文档.用法很简单.

增加.修改记事页:

记事本的VIewModel

有俩个View,同样我们也有俩个ViewModel:

列表页的ViewModel:

using Note.Command;
using Note.Commons;
using Note.Model;
using Note.Service;
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Note.ViewModel
{
    public class NoteListViewModel : ModelBase
    {
        private ObservableCollection notelist;
        public ObservableCollection Notelist
        {
            get
            {
                return notelist;
            }
            set
            { this.SetProperty(ref this.notelist, value); }
        }

        public DelegateCommand DeleteCommand { get; set; }
        public DelegateCommand EditCommand { get; set; }
        public DelegateCommand AddCommand { get; set; }

        public  NoteListViewModel()
        {

           GetList();
           AddCommand = new DelegateCommand(Add);
           DeleteCommand = new DelegateCommand(Delete);
           EditCommand = new DelegateCommand(Edit);
         }

       private async  void GetList()
        {

           List list = await DataService.Current.Query();

           Notelist = new ObservableCollection(list);
        }

        private void Edit(Object paramater)
        {
            int id = (int)paramater;
            NavigationHelp.NavigateTo(typeof(MainPage), id);
        }

        private  void Delete(Object paramater)
        {
            int id = (int)paramater;
            DataService.Current.Delete(id);
           for (int i = 0; i < Notelist.Count; i++)
            {
                if (Notelist[i].ID==id)
                {
                    Notelist.RemoveAt(i);
                }
            }
        }

        private void Add(Object paramater)
        {
            NavigationHelp.NavigateTo(typeof(MainPage));
        }
    }
}

增加修改页面的ViewModel:

using Note.Command;
using Note.Commons;
using Note.Model;
using Note.Service;
using Note.View;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Note.ViewModel
{
    class MainPageViewModel : ModelBase
    {

        private Notes notedemo;

        public Notes NoteDemo
        {
            get { return notedemo; }
            set
            { this.SetProperty(ref this.notedemo, value); }
        }

        public string  Title { get; set; }
        public DelegateCommand SaveCommand { get; set; }
        public DelegateCommand CancelCommand { get; set; }   

        public MainPageViewModel(int id)
        {

             Query(id);
            Title = "编辑记事";
            CancelCommand = new DelegateCommand(Cancel);
            SaveCommand = new DelegateCommand(Modify);

        }

       public MainPageViewModel()
        {
            NoteDemo = new Notes();
            Title = "新建记事";
            SaveCommand = new DelegateCommand(Add);
            CancelCommand = new DelegateCommand(Cancel);
         }

        private async void Query(int id)
        {
            NoteDemo = await DataService.Current.Query(id);
        }

        private void Modify()
     {

         DataService.Current.Modify(NoteDemo);
         NavigationHelp.NavigateTo(typeof(NoteListView));
     }
        private void Add()
        {
            DataService.Current.Add(NoteDemo);
            NavigationHelp.NavigateTo(typeof(NoteListView));
        }

        private void Cancel()
        {
            NavigationHelp.NavigateTo(typeof(NoteListView));
        }

    }
}

最后还要在APP.xaml.Cs页面中建立数据库:

StorageFolder localFolder = ApplicationData.Current.LocalFolder;
            IReadOnlyList files = await localFolder.GetFilesAsync();
            bool isExist = files.Any(file => file.Name == DbName);
            if (!isExist)
            {
                using (var db = new SQLiteConnection(localFolder.Path + "\\note.db"))
                {
                    db.CreateTable();
                }
            }

关于NavigationHelp导航类和自定义实现的命令类DelegateCommand我们之前都给出了源码.大家可以参考之前MVVM的文章.或者下载这个记事本的源码.

记事本应用源码下载

至此一个简单的记事本应用已经基本完成,大家可以按照我开篇提到的任意扩展.