ObservableCollection在window phone7中的应用

           ObservableCollection<T>是在WPF中出现的一个动态接口.官方文档中说:ObservableCollection是动态数据集合并且当集合中新增、修改或者删除项目时，或者集合被刷新时，都有通知机制(通过实现接口INotifyCollectionChanged)

           window phone 7是继承自SilverLight,而SilverLight又继承自WPF,所以在WP7中也有这个动态接口.我在做一个列表绑定的时候,想时时同步数据,而不重新再读取一遍数据.所以就用到了它.

           这里说明一点,我在使用它的时候,发展一个问题,在使用ObservableCollection绑定到listbox之后,使用remove移处数据的时候,它只是移除了ObservableCollection里的项,而没有真实的删除数据库里的值.但是却做到了.不用重新加载.

           这里要说明一点,这个接口,只能在添加和删除的时候才会看到变化,而在修改的时候,不会有变化

下面上代码.

          一,你要把你的实体类,实现INotifyCollectionChanged接口

     

public class BillingBookMerchant : INotifyPropertyChanged
    {
        //标识种子
        private int _merchantid;

        /// <summary>
        /// 标识种子
        /// </summary>
        [Column(IsPrimaryKey = true, IsDbGenerated = true, CanBeNull = false, DbType = "INT NOT NULL Identity", AutoSync = AutoSync.OnInsert)]
        public int MerchantId
        {
            get { return _merchantid; }
            set 
            {
                if (value != _merchantid)
                {
                    _merchantid = value;
                    NotifyPropertyChanged("MerchantId");
                }
            }
        }

        //商家名称
        private string _merchantname;

        /// <summary>
        /// 商家名称
        /// </summary>
        [Column(CanBeNull = false, DbType = "NVarChar(20) NOT NULL")]
        public string MerchantName
        {
            get { return _merchantname; }
            set 
            {
                if (value != _merchantname)
                {
                    _merchantname = value;
                    NotifyPropertyChanged("MerchantName");
                }
            }
        }

        //最后使用时间
        private DateTime _datetimes;

        /// <summary>
        /// 最后使用时间
        /// </summary>
        [Column(DbType = "DateTime")]
        public DateTime DateTimes
        {
            get { return _datetimes; }
            set 
            {
                if (value != _datetimes)
                {
                    _datetimes = value;
                    NotifyPropertyChanged("DateTimes");
                }
            }
        }

        public event PropertyChangedEventHandler PropertyChanged;

        private void NotifyPropertyChanged(string propertyName)
        {

            if (PropertyChanged != null)
            {

                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));

            }

        }

    }

前台代码;

<phone:PhoneApplicationPage xmlns:toolkit="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone.Controls.Toolkit"  
    x:Class="BillingBook.BillingBookMerchantList"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:phone="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone"
    xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    FontFamily="{StaticResource PhoneFontFamilyNormal}"
    FontSize="{StaticResource PhoneFontSizeNormal}"
    Foreground="{StaticResource PhoneForegroundBrush}"
    SupportedOrientations="Portrait" Orientation="Portrait"
    mc:Ignorable="d" d:DesignHeight="696" d:DesignWidth="480"
    shell:SystemTray.IsVisible="True">

    <!--LayoutRoot is the root grid where all page content is placed-->
    <Grid x:Name="LayoutRoot" Background="Transparent">
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>

        <!--TitlePanel contains the name of the application and page title-->
        <StackPanel x:Name="TitlePanel" Grid.Row="0" Margin="12,0" Height="50" Orientation="Horizontal">
            <HyperlinkButton x:Name="hlback" Content="返回" />
            <TextBlock Text="设置->商户" Margin="100,0" VerticalAlignment="Center"></TextBlock>
        </StackPanel>

        <!--ContentPanel - place additional content here-->
        <Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0">
            <!--<toolkit:GestureService.GestureListener>
                <toolkit:GestureListener Hold="GestureListener_Hold"></toolkit:GestureListener>
            </toolkit:GestureService.GestureListener>
            <toolkit:ContextMenuService.ContextMenu>
                <toolkit:ContextMenu Width="200">
                    <toolkit:MenuItem Header="编辑" Click="MenuItem_Click"></toolkit:MenuItem>
                    <toolkit:MenuItem Header="删除" Click="MenuItem_Click_1"></toolkit:MenuItem>
                </toolkit:ContextMenu>
            </toolkit:ContextMenuService.ContextMenu>-->
            <ListBox Height="auto" x:Name="lbMerchantList" VerticalAlignment="Top" Width="460">
               
                <ListBox.ItemTemplate>
                    <DataTemplate>
                        <StackPanel Orientation="Horizontal" VerticalAlignment="Center" Height="100">
                            <Image Width="40" VerticalAlignment="Center" Height="40" Source="/myIcons/Merchant.png" />
                            <TextBlock Margin="20,0"  VerticalAlignment="Center" Text="{Binding MerchantName,Mode=OneWay}" />
                        </StackPanel>
                    </DataTemplate>
                </ListBox.ItemTemplate>
            </ListBox>
        </Grid>
    </Grid>
 
    <!--Sample code showing usage of ApplicationBar-->
    <phone:PhoneApplicationPage.ApplicationBar>
        <shell:ApplicationBar IsVisible="True" IsMenuEnabled="True">
            <shell:ApplicationBarIconButton IconUri="/SystemImg/appbar.add.rest.png" Text="添加" Click="ApplicationBarIconButton_Click"/>
            <shell:ApplicationBarIconButton IconUri="/SystemImg/appbar.edit.rest.png" x:Name="btnEdit" Text="修改" Click="btnEdit_Click" />
            <shell:ApplicationBarIconButton IconUri="/SystemImg/appbar.delete.rest.png" Text="删除" Click="ApplicationBarIconButton_Click_1"/>
            <!--<shell:ApplicationBar.MenuItems>
                <shell:ApplicationBarMenuItem Text="MenuItem 1"/>
                <shell:ApplicationBarMenuItem Text="MenuItem 2"/>
            </shell:ApplicationBar.MenuItems>-->
        </shell:ApplicationBar>
    </phone:PhoneApplicationPage.ApplicationBar>

</phone:PhoneApplicationPage>

后台:我只是在删除功能中用到它

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using Microsoft.Phone.Controls;
using System.Collections.ObjectModel;

namespace BillingBook
{
    public partial class BillingBookMerchantList : PhoneApplicationPage
    {
        //初始化
        ObservableCollection<BillingBookMerchant> obsBBM = new ObservableCollection<BillingBookMerchant>();

        BillingBookDbBll bll = new BillingBookDbBll();

        public BillingBookMerchantList()
        {
            InitializeComponent();
        }

        protected override void OnNavigatedTo(System.Windows.Navigation.NavigationEventArgs e)
        {
            //base.OnNavigatedTo(e);

            
            //清空原有数据
            obsBBM.Clear();

            List<BillingBookMerchant> listBBM = bll.bbmerList();

            //将list<T>转化为ObservableCollection<T>
            foreach (var item in listBBM)
            {
                obsBBM.Add(item);
            }

            this.lbMerchantList.ItemsSource = obsBBM;
           
        }


        /// <summary>
        /// 添加新的记帐本商家
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void ApplicationBarIconButton_Click(object sender, EventArgs e)
        {
            this.NavigationService.Navigate(new Uri("/BillingBookMerchantEdit.xaml", UriKind.Relative));
        }


        /// <summary>
        /// 删除选中记帐本商家
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void ApplicationBarIconButton_Click_1(object sender, EventArgs e)
        {
            var reult = MessageBox.Show("你确定要删除吗?", "提示信息",MessageBoxButton.OKCancel);

            if (reult == MessageBoxResult.OK)
            {
                BillingBookMerchant delbbm = this.lbMerchantList.SelectedItem as BillingBookMerchant;
                int MerchantId = delbbm.MerchantId;

                int flag = bll.DelMerchant(MerchantId);

                if (flag > 0)
                {
                    MessageBox.Show("删除成功!", "提示信息", MessageBoxButton.OK);
                    obsBBM.Remove(delbbm);
                    return;
                }
                else
                {
                    MessageBox.Show("删除失败!", "提示信息", MessageBoxButton.OK);
                    return;
                }
            }
            else
            {
                return;
            }
        }


        /// <summary>
        /// 修改选择中的记帐本商家
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void btnEdit_Click(object sender, EventArgs e)
        {
            if (!string.IsNullOrEmpty(this.lbMerchantList.SelectedValue.ToString()))
            {
                int MerchantId = (this.lbMerchantList.SelectedItem as BillingBookMerchant).MerchantId;
                this.NavigationService.Navigate(new Uri("/BillingBookMerchantEdit.xaml?MerchantId=" + MerchantId + "", UriKind.Relative));
            }
            else
            {
                MessageBox.Show("请选择要修改记帐本商家!", "提示", MessageBoxButton.OK);
                return;
            }
        }

        
    }
}