WPF框架MVVM简单例子

MVVM——Model-View-ViewModel的缩写形式。

第三点很关键，因为在MVVM中，事件都被当成命令来进行处理，其中命令只能与具有Command属性的控件进行绑定。

namespace WpfApplication1
{
    //第一步：自然是数据部分了，即Model层的实现。在这里定义了一个Person类，其中包含了2个基本的属性。
    public class PersonModel
    {
        public string Name { get; set; }
        public int Age { get; set; }
    }
}

namespace WpfApplication1
{
    //为了进行测试，下面创建一个静态方法来获得测试数据。
    public class PersonDataHelper
    {
        public static ObservableCollection<PersonModel> GetPersons()
        {
            ObservableCollection<PersonModel> samplePersons = new ObservableCollection<PersonModel>();
            samplePersons.Add(new PersonModel() { Name = "张三", Age = 33 });
            samplePersons.Add(new PersonModel() { Name = "王五", Age = 22 });
            samplePersons.Add(new PersonModel() { Name = "李四", Age = 35 });
            samplePersons.Add(new PersonModel() { Name = "LearningHard", Age = 27 });
            return samplePersons;
        }
    }
}

namespace WpfApplication1
{
    //第二步：实现ViewModel层，实现数据和界面之间的逻辑。在视图模型类中，包含了属性和命令，
    //因为在MVVM中，事件都当成命令来进行处理，其中命令只能与具有Command属性的控件进行绑定。
    //既然要包含命令，首先就需要实现一个命令，这里自定义的命令需要实现ICommand接口。
    //这里我们定义了一个QueryCommand。具体的实现代码如下所示：
    public class QueryCommand : ICommand
    {
        #region Fields
        private Action _execute;
        private Func<bool> _canExecute;
        #endregion
        public QueryCommand(Action execute) : this(execute, null)
        {
        }
        public QueryCommand(Action execute, Func<bool> canExecute)
        {
            if (execute == null)
                throw new ArgumentNullException("execute");
            _execute = execute;
            _canExecute = canExecute;
        }
        #region ICommand Member
        public event EventHandler CanExecuteChanged
        {
            add
            {
                if (_canExecute != null)
                {
                    CommandManager.RequerySuggested += value;
                }
            }
            remove
            {
                if (_canExecute != null)
                {
                    CommandManager.RequerySuggested -= value;
                }
            }
        }
        public bool CanExecute(object parameter)
        {
            return _canExecute == null ? true : _canExecute();
        }
        public void Execute(object parameter)
        {
            _execute();
        }
        #endregion
    }
}

namespace WpfApplication1
{
    public class PersonListViewModel : INotifyPropertyChanged
    {
        #region Fields
        private string _searchText;
        private ObservableCollection<PersonModel> _resultList;
        #endregion
        #region Properties
        public ObservableCollection<PersonModel> PersonList { get; private set; }
        // 查询关键字
        public string SearchText
        {
            get { return _searchText; }
            set
            {
                _searchText = value;
                RaisePropertyChanged("SearchText");
            }
        }
        // 查询结果
        public ObservableCollection<PersonModel> ResultList
        {
            get { return _resultList; }
            set
            {
                _resultList = value;
                RaisePropertyChanged("ResultList");
            }
        }
        public ICommand QueryCommand
        {
            get { return new QueryCommand(Searching, CanSearching); }
        }
        #endregion
        #region Construction
        public PersonListViewModel()
        {
            PersonList = PersonDataHelper.GetPersons();
            _resultList = PersonList;
        }
        #endregion
        #region Command Handler
        public void Searching()
        {
            ObservableCollection<PersonModel> personList = null;
            if (string.IsNullOrWhiteSpace(SearchText))
            {
                ResultList = PersonList;
            }
            else
            {
                personList = new ObservableCollection<PersonModel>();
                foreach (PersonModel p in PersonList)
                {
                    if (p.Name.Contains(SearchText))
                    {
                        personList.Add(p);
                    }
                }
                if (personList != null)
                {
                    ResultList = personList;
                }
            }
        }
        public bool CanSearching()
        {
            return true;
        }
        #endregion
        #region INotifyPropertyChanged Members
        public event PropertyChangedEventHandler PropertyChanged;
        #endregion
        #region Methods
        private void RaisePropertyChanged(string propertyName)
        {
            // take a copy to prevent thread issues
            PropertyChangedEventHandler handler = PropertyChanged;
            if (handler != null)
            {
                handler(this, new PropertyChangedEventArgs(propertyName));
            }
        }
        #endregion
    }
}

<Window x:Class="WpfApplication1.PersonsView"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:WpfApplication1"
        Title="PersonsView" Height="300" Width="300">
    <Window.DataContext>
        <local:PersonListViewModel />
    </Window.DataContext>
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="50"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>
        <TextBox Grid.Row="0" Name="searchtxt" Text="{Binding Path=SearchText, Mode=TwoWay}" 
                 HorizontalAlignment="Left" Height="30" Width="280" Margin="10,0,0,0">
        </TextBox>
        <Button Grid.Row="0" Name="searchBtn" Content="Search" Command="{Binding Path=QueryCommand}" 
                Width="80" Height="30" HorizontalAlignment="Right" Margin="0,0,10,0">
        </Button>
        <DataGrid Grid.Row="1" Name="datGrid" 
                  HorizontalAlignment="Center"
                  VerticalAlignment="Top" ItemsSource="{Binding Path=ResultList}" Width="300">
        </DataGrid>
    </Grid>
</Window>