虽然最近业余时间主要都放在研究AngularJS上了，不过由于正好要帮朋友做一个生成XML的小工具，顺便又温顾了一下WPF。虽然这个时代相对于Web应用和移动App，Windows应用程序是越来越少了，但是微软并未因此放弃它，反而推出了强大的WPF，让Windows应用程序的制作变得更优雅、更高效。
在我看来，WPF最大的强项就是布局和绑定了。WPF引入了MVVM的编程模式，并结合页面绑定，让UI和业务逻辑完全可以分离由不同的人去完成，而且只要View-Model保持稳定，对于View的布局变动将不受任何限制。因此WPF的编程思维和Winform已经完全不一样，如果你是一个从来没用过WPF的Winform程序员，你首要要做的应该是改变你的思维模式。
案例需求
需要一个工具，按照某机构的官方文档要求，数据由用户通过程序界面输入，最终生成指定格式的XML文件（某机构已提供XSLT文件，因此生成的XML可以在浏览器中展示出统一的格式。关于XSLT并不在本篇讨论范围内，以后有机会可以另外开篇再说）。
Winform的思路
- 拖控件布局
- 创建控件的各种事件
- 通过后台代码控制界面布局以及元素行为
- 后台代码获取元素的值并将他们赋值给所需的对象
- 写非常复杂的if-else逻辑生成所需的XML
- 如果需要将生成的XML重新绑定到页面上，又是写一遍非常复杂的逻辑进行页面控件赋值
WPF的思维
- 将XML抽象成实体类
- 创建实例并将它设置为View的DataContext
- 将实例的各个属性绑定到View的各个控件中
- 按需在界面上填写数据后，将实例序列化成XML
- 如果需要将生成的XML重新绑定到页面上，将文件内容反序列化为实例对象，绑定到DataContext即可
光看文字描述，对于不熟悉WPF的人来说可能很难分清他们的区别，我们看下具体代码吧。为了简化业务，我重新写了一个Demo，通过页面上输入班级、老师、学生信息，生成一个包含班级信息的XML文件。
步骤1：抽象XML实体对象
为了能让实体对象的实例最终和View进行自动的双向绑定，我们需要将所有实体类实现INotifyPropertyChanged接口，为了进一步抽象代码，我们首先创建一个实现了INotifyPropertyChanged的基类，所有实体类将继承该基类。
public abstract class ClassBase : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
protected void NotifyPropertyChange(string propertyName)
{
if (PropertyChanged != null)
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
班级类（老师、学生属性使用ObservableCollection集合，可以使集合变动时界面也自动刷新布局）：
[XmlRoot(ElementName = "class")]
public class MyClass : ClassBase
{
private string _grade;
[XmlAttribute(AttributeName = "grade", Namespace = "")]
public string Grade
{
get
{
return _grade;
}
set
{
_grade = value;
NotifyPropertyChange("Grade");
}
} private string _classID;
[XmlAttribute(AttributeName = "class-id", Namespace = "")]
public string ClassID
{
get
{
return _classID;
}
set
{
_classID = value;
NotifyPropertyChange("ClassID");
}
} private ObservableCollection<MyTeacher> _teachers;
[XmlElement(ElementName = "teachers", Namespace = "")]
public ObservableCollection<MyTeacher> Teachers
{
get
{
return _teachers;
}
set
{
_teachers = value;
NotifyPropertyChange("Teachers");
}
} private ObservableCollection<MyStudent> _students;
[XmlElement(ElementName = "students", Namespace = "")]
public ObservableCollection<MyStudent> Students
{
get
{
return _students;
}
set
{
_students = value;
NotifyPropertyChange("Students");
}
}
}
老师类：
[XmlRoot(ElementName = "teacher")]
public class MyTeacher : ClassBase
{
private string _name;
[XmlElement(ElementName = "name", Namespace = "")]
public string Name
{
get
{
return _name;
}
set
{
_name = value;
NotifyPropertyChange("Name");
}
} private string _teachingFor;
[XmlElement(ElementName = "teaching-for", Namespace = "")]
public string TeachingFor
{
get
{
return _teachingFor;
}
set
{
_teachingFor = value;
NotifyPropertyChange("TeachingFor");
}
} private string _comments;
[XmlElement(ElementName = "comments", Namespace = "")]
public string Comments
{
get
{
return _comments;
}
set
{
_comments = value;
NotifyPropertyChange("Comments");
}
}
}
学生类：
[XmlRoot(ElementName = "student")]
public class MyStudent : ClassBase
{
private string _name;
[XmlElement(ElementName = "name", Namespace = "")]
public string Name
{
get
{
return _name;
}
set
{
_name = value;
NotifyPropertyChange("Name");
}
} private int _age;
[XmlElement(ElementName = "age", Namespace = "")]
public int Age
{
get
{
return _age;
}
set
{
_age = value;
NotifyPropertyChange("Age");
}
} private string _gender;
[XmlElement(ElementName = "gender", Namespace = "")]
public string Gender
{
get
{
return _gender;
}
set
{
_gender = value;
NotifyPropertyChange("Gender");
}
}
}
OK，至此为止，我们Demo所需的XML实体类已抽象完毕。
步骤2：创建实例并将它设置为View的DataContext
public partial class MainWindow : Window
{
// 创建空实例
private MyClass _myClassInfo = new MyClass(); public MainWindow()
{
InitializeComponent(); //将空实例设置为View的DataContext
base.DataContext = _myClassInfo;
}
}
对，你没看错，这一步就是如此简单！其实就注释的那2行代码而已！
步骤3：将实例的各个属性绑定到View的各个空间中
班级信息界面代码：
<TextBlock Grid.Row="0" Grid.Column="0" Text="Grade:"></TextBlock>
<ComboBox Grid.Row="0" Grid.Column="1" Text="{Binding Path=Grade}">
<ComboBoxItem Content="Grade 1"></ComboBoxItem>
<ComboBoxItem Content="Grade 2"></ComboBoxItem>
<ComboBoxItem Content="Grade 3"></ComboBoxItem>
<ComboBoxItem Content="Grade 4"></ComboBoxItem>
<ComboBoxItem Content="Grade 5"></ComboBoxItem>
</ComboBox> <TextBlock Grid.Row="1" Grid.Column="0" Text="ClassID:"></TextBlock>
<TextBox Grid.Row="1" Grid.Column="1" Text="{Binding Path=ClassID}"></TextBox>
老师信息界面代码：
<GroupBox Header="Teachers" Grid.Row="2" Grid.ColumnSpan="2">
<ContentControl>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="*"></RowDefinition>
<RowDefinition Height="30"></RowDefinition>
</Grid.RowDefinitions> <TabControl x:Name="tabTeachers" ItemsSource="{Binding Path=Teachers}">
<TabControl.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Path=Name, Converter={StaticResource TeacherNameConverter}}" MinWidth="30"></TextBlock>
</DataTemplate>
</TabControl.ItemTemplate>
<TabControl.ContentTemplate>
<DataTemplate>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="160"></ColumnDefinition>
<ColumnDefinition Width="*"></ColumnDefinition>
</Grid.ColumnDefinitions> <Grid.RowDefinitions>
<RowDefinition Height="30"></RowDefinition>
<RowDefinition Height="30"></RowDefinition>
<RowDefinition Height="30"></RowDefinition>
</Grid.RowDefinitions> <Label Grid.Row="0" Grid.Column="0" Content="Teacher name"></Label>
<TextBox Grid.Row="0" Grid.Column="1" Text="{Binding Path=Name}"></TextBox> <Label Grid.Row="1" Grid.Column="0" Content="Teaching for"></Label>
<TextBox Grid.Row="1" Grid.Column="1" Text="{Binding Path=TeachingFor}"></TextBox> <Label Grid.Row="2" Grid.Column="0" Content="Comments"></Label>
<TextBox Grid.Row="2" Grid.Column="1" Text="{Binding Path=Comments}"></TextBox>
</Grid>
</DataTemplate>
</TabControl.ContentTemplate>
</TabControl> <StackPanel Grid.Row="1" Orientation="Horizontal" HorizontalAlignment="Center">
<Button Name="btnNewTeacher" Content="Create New Teacher" Width="150" Margin="0,0,20,0" Click="btnNewTeacher_Click"></Button>
<Button Name="btnDeleteTeacher" Content="Delete Current Teacher" Width="150" Click="btnDeleteTeacher_Click"></Button>
</StackPanel>
</Grid>
</ContentControl>
</GroupBox>
学生信息界面代码：
<GroupBox Header="Students" Grid.Row="3" Grid.ColumnSpan="2">
<ContentControl>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="*"></RowDefinition>
<RowDefinition Height="30"></RowDefinition>
</Grid.RowDefinitions> <TabControl x:Name="tabStudents" ItemsSource="{Binding Path=Students}">
<TabControl.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Path=Name, Converter={StaticResource StudentNameConverter}}" MinWidth="30"></TextBlock>
</DataTemplate>
</TabControl.ItemTemplate>
<TabControl.ContentTemplate>
<DataTemplate>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="160"></ColumnDefinition>
<ColumnDefinition Width="*"></ColumnDefinition>
</Grid.ColumnDefinitions> <Grid.RowDefinitions>
<RowDefinition Height="30"></RowDefinition>
<RowDefinition Height="30"></RowDefinition>
<RowDefinition Height="30"></RowDefinition>
</Grid.RowDefinitions> <Label Grid.Row="0" Grid.Column="0" Content="Student name"></Label>
<TextBox Grid.Row="0" Grid.Column="1" Text="{Binding Path=Name}"></TextBox> <Label Grid.Row="1" Grid.Column="0" Content="Age"></Label>
<TextBox Grid.Row="1" Grid.Column="1" Text="{Binding Path=Age}"></TextBox> <Label Grid.Row="2" Grid.Column="0" Content="Gender"></Label>
<ComboBox Grid.Row="2" Grid.Column="1" Text="{Binding Path=Gender}">
<ComboBoxItem Content="Male"></ComboBoxItem>
<ComboBoxItem Content="Female"></ComboBoxItem>
</ComboBox>
</Grid>
</DataTemplate>
</TabControl.ContentTemplate>
</TabControl> <StackPanel Grid.Row="1" Orientation="Horizontal" HorizontalAlignment="Center">
<Button Name="btnNewStudent" Content="Create New Student" Width="150" Margin="0,0,20,0" Click="btnNewStudent_Click"></Button>
<Button Name="btnDeleteStudent" Content="Delete Current Student" Width="150" Click="btnDeleteStudent_Click"></Button>
</StackPanel>
</Grid>
</ContentControl>
</GroupBox>
步骤4：按需在界面上填写数据后，将实例序列化成XML
string xmlFilePath = txtFilePath.Text.Trim();
if (!string.IsNullOrEmpty(xmlFilePath))
{
XmlWriterSettings settings = new XmlWriterSettings()
{
Encoding = Encoding.UTF8,
OmitXmlDeclaration = true,
NewLineOnAttributes = true,
Indent = true,
ConformanceLevel = ConformanceLevel.Document
}; XmlSerializerNamespaces ns = new XmlSerializerNamespaces();
ns.Add("", ""); using (FileStream fs = new FileStream(xmlFilePath, FileMode.Create))
using (var writer = XmlWriter.Create(fs, settings))
{
writer.WriteRaw("<?xml version=\"1.0\" encoding=\"UTF-8\"?>\r\n"); XmlSerializer xmlSerializer = new XmlSerializer(typeof(MyClass));
xmlSerializer.Serialize(writer, _myClassInfo, ns);
System.Windows.Forms.MessageBox.Show("Success!");
}
}
else
{
System.Windows.Forms.MessageBox.Show("Choose a file path to save!");
}
步骤5：读取已有的XML绑定到页面上
OpenFileDialog dialog = new OpenFileDialog();
dialog.DefaultExt = "xml";
dialog.Filter = "XML documents (*.xml)|*.xml";
dialog.FileName = "my-class-test"; var dr = dialog.ShowDialog();
if (dr == System.Windows.Forms.DialogResult.OK)
{
txtFilePath.Text = dialog.FileName; using (FileStream fs = File.OpenRead(dialog.FileName))
{
XmlSerializer xmlSerializer = new XmlSerializer(typeof(MyClass));
_myClassInfo = xmlSerializer.Deserialize(fs) as MyClass;
base.DataContext = _myClassInfo; this.tabStudents.SelectedIndex = ;
this.tabTeachers.SelectedIndex = ;
}
}
好了，这样程序就已经完成了。你没看错，这已经是几乎所有代码了！是不是很不可思议？你可能已经有心理准备，WPF将会以非常优雅的代码完成我们所需的逻辑，但是这也太神奇了！区区百行代码竟然完成了Winform中可能需要数倍代码量的逻辑！想象中的后台组装MyClass实例并生成XML的代码竟然都已经由WPF的双向绑定方式悄悄帮你做完了！
看完这个示例，你是否也开始蠢蠢欲动，想自己动手试试写一个属于自己的WPF程序了呢？当然如果你已经等不及了，你也可以先下载附录中的源码运行一下，一睹为快。
附录
本文Demo完整源码下载地址（VS2012）：http://files.cnblogs.com/files/wushangjue/WpfDemo.zip