<win8>（二）实例讲解win8(XAML+C#)开发课程表：数据绑定

免责声明：本文章由fengyun1989创作，采用知识共享署名-非商业性使用-相同方式共享 2.5 中国大陆许可协议进行许可。

　　首先，打开VS2012，然后新建一个工程，命名为TimeTable。

点击确定后，看到编译器如下地方：

现在空的工程也可以运行，选择Simulator就是模拟器运行，选择本地计算机就是直接在本机运行。现在就可以运行看看，就是黑屏。

在本机运行的话，如果想退出程序，可以把光标放到左上角，等待出现桌面缩略图就点击，这样就能退出了。

数据绑定

　　细想下这个工程，首先要做的是要把课程的数据显示出来，那么，就要用到数据绑定了。熟悉wp7和silverlight开发的朋友，接下来你就会发现，在win8（XAML+c#）开发当中，数据绑定是一样的。

　　首先，我们修改下我们的工程，新建一个命名为Resources.然后在 文件夹右键--添加--新建项,选取资源字典。命名为：MyDictionary.xaml。添加一行画刷来作为背景。并且修改代码如下：

<ResourceDictionary
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:TimeTable.Resources">
    <SolidColorBrush Color="#3E790A" x:Key="AppBackgroundColor"/>
</ResourceDictionary>

现在打开App.xaml。添加对MyDicitonary.xaml的声明。修改如下：

<ResourceDictionary.MergedDictionaries>

                <!-- 
                    Styles that define common aspects of the platform look and feel
                    Required by Visual Studio project and item templates
                 -->
                <ResourceDictionary Source="Common/StandardStyles.xaml"/>
                <ResourceDictionary Source="Resources/MyDictionary.xaml"/>
            </ResourceDictionary.MergedDictionaries>

现在修改MainPage.xaml的grid的背景。

<Grid Background="{StaticResource AppBackgroundColor}">

现在，就能看到背景色变为了深绿色。接下来就进行数据定义吧。我们的数据类都继承INotifyPropertyChanged接口，以便数据更新的时候能够自己通知控件更新。添加一个Data的文件夹。然后新建添加三个类，分别是ViewModel.cs,WeekdayItem.cs,ScheduleItem.cs .类图如下：

代码如下：

class ViewModel : INotifyPropertyChanged
    {
        private ObservableCollection<WeekdayItem> weekdayList;
        public ObservableCollection<WeekdayItem> WeekdayList { get { return weekdayList; } }
        private int selectedItemIndex;
        public int SelectedItemIndex
        {
            get { return selectedItemIndex; }
            set { selectedItemIndex = value; NotifyPropertyChanged("SelectedItemIndex"); }
        }

        public ViewModel()
        {
            weekdayList = new ObservableCollection<WeekdayItem>();
            selectedItemIndex = -1;
        }

        public event PropertyChangedEventHandler PropertyChanged;
        private void NotifyPropertyChanged(string propName)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(propName));
            }
        }
    }

class WeekdayItem : INotifyPropertyChanged
    {
        private ObservableCollection<ScheduleItem> scheduleList;
        private int scheduleSelected;
        public int ScheduleSelected
        {
            get { return scheduleSelected; }
            set { scheduleSelected = value; NotifyPropertyChanged("ScheduleSelected"); }
        }
        public ObservableCollection<ScheduleItem> ScheduleList
        {
            get { return scheduleList; }
        }
        public WeekdayItem()
        {
            scheduleList = new ObservableCollection<ScheduleItem>();
            weekday = "Monday";
        }
        private string weekday;
        public string Weekday
        {
            get { return weekday; }
            set { weekday = value; NotifyPropertyChanged("WeekDay"); }
        }

        public event PropertyChangedEventHandler PropertyChanged;
        private void NotifyPropertyChanged(string propName)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(propName));
            }
        }
    }

class ScheduleItem : INotifyPropertyChanged
    {
        private string lessonName;
        public string LessonName
        {
            get { return lessonName; }
            set
            {
                lessonName = value;
                NotifyPropertyChanged("LessonName");
            }
        }
        private string startTime;
        public string StartTime
        {
            get
            {
                return startTime;
            }
            set
            {
                startTime = value;
                NotifyPropertyChanged("StartTme");
            }
        }

        private string endTime;
        public string EndTime
        {
            get { return endTime; }
            set
            {
                endTime = value;
                NotifyPropertyChanged("EndTime");
            }
        }

        private string classRoom;
        public string ClassRoom
        {
            get { return classRoom; }
            set { classRoom = value; NotifyPropertyChanged("ClassRoom"); }
        }

        public event PropertyChangedEventHandler PropertyChanged;
        private void NotifyPropertyChanged(string propName)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(propName));
            }
        }
    }

上面的代码已经很清楚了。就不多说了。

下面进行数据绑定。首先，在MyDictionary.xaml的SolidColorBrush的下面添加下面一段代码：

<Style x:Key="WeekdayListStyle" TargetType="TextBlock" BasedOn="{Binding BasicTextStyle}" >
        <Setter Property="FontSize" Value="45"/>
        <Setter Property="FontWeight" Value="Light"/>
        <Setter Property="Margin" Value="10,0"/>
        <Setter Property="VerticalAlignment" Value="Center"/>
    </Style>
    <DataTemplate x:Key="WeekdayListItemTemplate">
        <TextBlock Text="{Binding Weekday}" Style="{StaticResource WeekdayListStyle}"/>
    </DataTemplate>

上面定义了一个数据模板，BasicTextStyle定义在Common/StandardStyles.xaml里面，这个文件里面定义了很多style。

下面修改MainPage的Grid。

<Grid Background="{StaticResource AppBackgroundColor}">
        <Grid.ColumnDefinitions>
            <ColumnDefinition />
            <ColumnDefinition/>
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition/>
            <RowDefinition/>
        </Grid.RowDefinitions>
        <StackPanel Grid.RowSpan="2">
            <TextBlock x:Name="WeekdayListTitle" Style="{StaticResource HeaderTextStyle}" Margin="10"
                       Text="Weekday List"/>
            <ListView x:Name="weekdayList"  Grid.RowSpan="2" 
                      ItemsSource="{Binding WeekdayList}"
                      ItemTemplate="{StaticResource WeekdayListItemTemplate}" >
            </ListView>

        </StackPanel>
        <StackPanel Orientation="Vertical" Grid.Column="1" Grid.RowSpan="2">
            <TextBlock Style="{StaticResource HeaderTextStyle}" Margin="10" x:Name="ItemDetailTitle"
                       Text="Schedule Detail"/>
            <Frame x:Name="ItemDetailFrame"/>
        </StackPanel> 
    </Grid>

上面定义的style除了自己定义的，基本都是在Common/StandardStyles.xaml里面。熟悉数据绑定的能在上面的代码看到熟悉的代码影吧。绑定了ListView的ItemsSource和ItemTemplate。下面的Frame标签以后再讲。

然后修改后台的构造函数和添加一个函数来往viewModel添加数据。

ViewModel viewModel;
        public MainPage()
        {
            viewModel = new ViewModel();
            addData();
            this.DataContext = viewModel;
            this.InitializeComponent();
        }

        /// <summary>
        /// 往viewModel添加数据
        /// </summary>
        private void addData()
        {
            WeekdayItem monday = new WeekdayItem();
            monday.ScheduleList.Add(new ScheduleItem
            {
                ClassRoom = "B-215",
                StartTime = "8:30",
                EndTime = "10:00",
                LessonName = "Math"
            });
            monday.ScheduleList.Add(new ScheduleItem
            {
                ClassRoom = "B-216",
                StartTime = "10:30",
                EndTime = "12:00",
                LessonName = "Physic"
            });
            monday.ScheduleList.Add(new ScheduleItem
            {
                ClassRoom = "E-303",
                StartTime = "14:30",
                EndTime = "16:00",
                LessonName = "Computer"
            });
            monday.Weekday = "星期一";
            viewModel.WeekdayList.Add(monday);
            WeekdayItem tuesday = new WeekdayItem();
            tuesday.Weekday = "星期二";
            tuesday.ScheduleList.Add(new ScheduleItem
            {
                ClassRoom = "B-215",
                StartTime = "8:30",
                EndTime = "10:00",
                LessonName = "Math"
            });
            tuesday.ScheduleList.Add(new ScheduleItem
            {
                ClassRoom = "B-216",
                StartTime = "10:30",
                EndTime = "12:00",
                LessonName = "Physic"
            });
            tuesday.ScheduleList.Add(new ScheduleItem
            {
                ClassRoom = "E-303",
                StartTime = "14:30",
                EndTime = "16:00",
                LessonName = "English"
            });
            viewModel.WeekdayList.Add(tuesday);

            WeekdayItem wednesday = new WeekdayItem();
            wednesday.Weekday = "星期三";
            wednesday.ScheduleList.Add(new ScheduleItem
            {
                ClassRoom = "B-215",
                StartTime = "8:30",
                EndTime = "10:00",
                LessonName = "数学"
            });
            wednesday.ScheduleList.Add(new ScheduleItem
            {
                ClassRoom = "B-216",
                StartTime = "10:30",
                EndTime = "12:00",
                LessonName = "Physic"
            });
            wednesday.ScheduleList.Add(new ScheduleItem
            {
                ClassRoom = "E-303",
                StartTime = "14:30",
                EndTime = "16:00",
                LessonName = "English"
            });
            viewModel.WeekdayList.Add(wednesday);
            WeekdayItem thursday = new WeekdayItem();
            thursday.Weekday = "星期四";
            thursday.ScheduleList.Add(new ScheduleItem
            {
                ClassRoom = "B-215",
                StartTime = "8:30",
                EndTime = "10:00",
                LessonName = "数学"
            });
            thursday.ScheduleList.Add(new ScheduleItem
            {
                ClassRoom = "B-216",
                StartTime = "10:30",
                EndTime = "12:00",
                LessonName = "Physic"
            });
            thursday.ScheduleList.Add(new ScheduleItem
            {
                ClassRoom = "E-303",
                StartTime = "14:30",
                EndTime = "16:00",
                LessonName = "English"
            });
            viewModel.WeekdayList.Add(thursday);
            WeekdayItem friday = new WeekdayItem();
            friday.Weekday = "星期五";
            friday.ScheduleList.Add(new ScheduleItem
            {
                ClassRoom = "B-215",
                StartTime = "8:30",
                EndTime = "10:00",
                LessonName = "数学"
            });
            friday.ScheduleList.Add(new ScheduleItem
            {
                ClassRoom = "B-216",
                StartTime = "10:30",
                EndTime = "12:00",
                LessonName = "Physic"
            });
            friday.ScheduleList.Add(new ScheduleItem
            {
                ClassRoom = "E-303",
                StartTime = "14:30",
                EndTime = "16:00",
                LessonName = "English"
            });
            viewModel.WeekdayList.Add(friday);

        }

在构造函数，我们指定了当前页面的信息源DataContext为当前声明的viewModel。现在编译运行，就能看到运行结果如下：

　　下面我们要使用frame这个标签了。其实，每个页面都有这个Frame这个属性，这个Frame直接控制了导航，导航在Wp7里是用navigationService来完成的。不过可能是由于平板的屏幕大，所以用这个Frame标签就可以做到局部导航。使之可以所有操作都在一个页面完成。不过，如果开发者不实现导航返回按钮，win8平板就中间一个window键。如果能够返回上一层页面？至少我还没发现什么操作可以实现。

　　下面先给ListView添加一个SelectionChanged事件。当选项改变时触发。

        private void weekdayList_SelectionChanged_1(object sender, SelectionChangedEventArgs e)
        {
            viewModel.SelectedItemIndex = weekdayList.SelectedIndex;
        }

只做了一件事，就是修改了viewModel的SelectedItemIndex的值。那么我们要注册一个PropertyChanged事件，监听当这个SelectedItemIndex改变的时候做相应的工作。

在Mainpage的构造函数最后添加：

viewModel.PropertyChanged += (sender, args) => {
                if (args.PropertyName == "SelectedItemIndex")
                {
                    if (viewModel.SelectedItemIndex == -1)
                    {
                        ItemDetailFrame.Navigate(typeof(NoItemSelected));
                    }
                    else
                    {
                        ItemDetailFrame.Navigate(typeof(ItemDetail), viewModel);
                    }
                }
            };

上面我们监听了SelectedItemIndex。当改变的时候使ItemDetailFrame这个Frame导航到不同的页面。这个navigate方法，由VS2012的智能提示就知道，可以带参数，也可以不带参数。

下面我们新建一个文件夹Pages。然后添加一个空页面NoItemSelected.xaml。修改代码如下：

<Grid Background="{StaticResource AppBackgroundColor}">
        <TextBlock Style="{StaticResource HeaderTextStyle}"
                   FontSize="30" Text="No Item Selected"/>
    </Grid>

然后再添加一个空白页ItemDetail.xaml到Pages文件夹。修改代码如下：

<Grid Background="{StaticResource AppBackgroundColor}">
        <ListView x:Name="ScheduleList" ItemsSource="{Binding ScheduleList}"    
                  IsHoldingEnabled="True"   
                  ItemTemplate="{StaticResource ScheduleListItemTemplate}"/>
    </Grid>

然后修改ItemDetail页面的OnNavigateTo方法并添加一个变量。

ViewModel viewModel;

protected override void OnNavigatedTo(NavigationEventArgs e)
        {
            viewModel = e.Parameter as ViewModel;
            this.DataContext = viewModel.WeekdayList[viewModel.SelectedItemIndex];
            viewModel.PropertyChanged += (sender, args) =>
            {
                if (viewModel.SelectedItemIndex == -1)
                {
                    this.DataContext = null;
                }
                else
                    this.DataContext = viewModel.WeekdayList[viewModel.SelectedItemIndex];
            };
        }

上面OnNavigateTo方法，在页面进入的时候，就获取页面传递过来的ViewModel这个数据。然后指定当前选择的Weekday为数据源。

上面我们还没定义ItemDetail页面ListView的数据模版。在MyDictionary.xaml添加如下模版：

<DataTemplate x:Key="ScheduleListItemTemplate">
        <StackPanel Orientation="Vertical">
            <TextBlock Text="{Binding LessonName}" FontSize="30"/>
            <StackPanel Orientation="Horizontal">
                <TextBlock Text="{Binding StartTime}" FontSize="18"/>
                <TextBlock Text="-" FontSize="18"/>
                <TextBlock Text="{Binding EndTime}" FontSize="18"/>
            </StackPanel>
            <TextBlock Text="{Binding ClassRoom}" FontSize="30"/>
        </StackPanel>
    </DataTemplate>

这样，编译运行，就能看到选择左边的WeekdayList就能改变右边的ItemDetail部分了。到此，数据绑定部分基本就这样吧。还有部分弹出窗口的数据绑定到后面再说。

继续学习：<win8>(三)实例讲解win8(XAML+C#)开发--------课程表:弹出菜单ContextMenu和弹窗Flyout

本次工程下载：http://dl.dbank.com/c0eh4b1z85