当Source端Path所关联的数据与Target端目标属性数据类型不一致时，需要添加数据转换器，数据转换器是一个自定义的类，这个类需要实现IValueConverter接口，这个接口有两个方法需要实现：Convert和ConvertBack，当数据从Source流向Target时，将调用Convert方法，反之，将调用ConvertBack方法

例子，首先定义飞机类型

    public enum Category

    {

        Bomber,

        Fighter

    }

    public enum State

    {

        Available,

        Locked,

        Unknown

    }

    public class Plane

    {

        public Category Category { get; set; }

        public string Name { get; set; }

        public State State { get; set; }

    }

Plane类型的Category将在界面上转换为图片，而State类型将会转换成界面上的CheckBox显示，由于存在两个转换，因此需要提供两个Converter，第一个转换是做Category类型与字符类型的转换，字符串是图片的路径

    class CategoryToSourceConverter : IValueConverter

    {

        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)

        {

            Category c = (Category)value;

            switch (c)

            {

                case Category.Bomber:

                    {

                        return @"\Icons\close.png";

                    }

                case Category.Fighter:

                    {

                        return @"\Icons\closeing.png";

                    }

                default:

                    {

                        return null;

                    }

            }

        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)

        {

            return new NotImplementedException();

        }

    }

由于UI上不能修改图片，所以只实现了从Source到Target的转换

另一个转换用于将State数据转换为bool?

    public class StateToNullableBoolConverter : IValueConverter

    {

        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)

        {

            State s = (State)value;

            switch (s)

            {

                case State.Locked:

                    {

                        return false;

                    }

                case State.Available:

                    {

                        return true;

                    }

                case State.Unknown:

                default:

                    {

                        return null;

                    }

            }

        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)

        {

            bool? nb = (bool?)value;

            switch (nb)

            {

                case true:

                    {

                        return State.Available;

                    }

                case false:

                    {

                        return State.Locked;

                    }

                case null:

                default:

                    {

                        return State.Unknown;

                    }

            }

        }

    }

界面代码：

<Window x:Class="WpfApplication1.MainWindow"

        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

        xmlns:local="clr-namespace:WpfApplication1"

        Title="MainWindow" Height="275" Width="275">

    <Window.Resources>

        <local:CategoryToSourceConverter x:Key="cts" />

        <local:StateToNullableBoolConverter x:Key="stnb" />

    </Window.Resources>

    <StackPanel Background="LightBlue">

        <ListBox x:Name="listBoxPlane" Height="160" Margin="5">

            <ListBox.ItemTemplate>

                <DataTemplate>

                    <StackPanel Orientation="Horizontal">

                        <Image Width="20" Height="20" Source="{Binding Path=Category, Converter={StaticResource cts}}" />

                        <TextBlock Text="{Binding Path=Name}" Width="60" Margin="80,0" />

                        <CheckBox IsThreeState="True" IsChecked="{Binding Path=State, Converter={StaticResource stnb}}" />

                    </StackPanel>

                </DataTemplate>

            </ListBox.ItemTemplate>

        </ListBox>

        <Button x:Name="buttonLoad" Content="Load" Height="25" Margin="5,0" Click="buttonLoad_Click" />

        <Button x:Name="buttonSave" Content="Save" Height="25" Margin="5,0" Click="buttonSave_Click" />

    </StackPanel>

</Window>

加粗的部分是XAML中对转换器的使用，后台代码中实现了Load和Save两个按钮的点击事件

        private void buttonLoad_Click(object sender, RoutedEventArgs e)

        {

            List<Plane> planeList = new List<Plane>()

            {

                new Plane(){Category=Category.Bomber, Name="B-1", State=State.Unknown},

                new Plane(){Category=Category.Bomber, Name="B-2", State=State.Unknown},

                new Plane(){Category=Category.Fighter, Name="F-22", State=State.Unknown},

                new Plane(){Category=Category.Fighter, Name="Su-47", State=State.Unknown},

                new Plane(){Category=Category.Bomber, Name="B-52", State=State.Unknown},

                new Plane(){Category=Category.Fighter, Name="J-10", State=State.Unknown}

            };

            listBoxPlane.ItemsSource = planeList;

        }

        private void buttonSave_Click(object sender, RoutedEventArgs e)

        {

            StringBuilder sb = new StringBuilder();

            foreach (Plane p in listBoxPlane.Items)

            {

                sb.AppendLine(string.Format("Category={0}, Name={1}, State={2}", p.Category, p.Name, p.State));

            }

            File.WriteAllText(@"d:\PlaneList.txt", sb.ToString());

        }

界面效果如图：

当改变checkbox的选中状态时，Plane对象中的值会发生变化