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Windows Phone 7 MVVM模式通讯方式之实现Command

2011-06-23 15:17 357 查看
MVVM模式的View与ViewModel的三大通讯方式：Binding Data（实现数据的传递）、Command（实现操作的调用）和Attached Behavior（实现控件加载过程中的操作）。
(1)Windows Phone 7 MVVM模式通讯方式之实现Binding Data。
(2)Windows Phone 7 MVVM模式通讯方式之实现Command。
(3)Windows Phone 7 MVVM模式通讯方式之实现Attached Behavior。
下面通过一个实例实现MVVM模式的Command通讯



（1）MainPage.xaml文件的代码,实现View层

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<
phone:PhoneApplicationPage
x:Class
=
"CommandDemo.MainPage"
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"
xmlns:my
=
"clr-namespace:CommandDemo.ViewModel"
xmlns:my_Interactivity
=
"clr-namespace:CommandDemo.Command"
xmlns:Custom
=
"clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
xmlns:ic
=
"clr-namespace:Microsoft.Expression.Interactivity.Core;assembly=Microsoft.Expression.Interactions"
mc:Ignorable
=
"d"
d:DesignWidth
=
"480"
d:DesignHeight
=
"768"
FontFamily
=
"{StaticResource PhoneFontFamilyNormal}"
FontSize
=
"{StaticResource PhoneFontSizeNormal}"
Foreground
=
"{StaticResource PhoneForegroundBrush}"
SupportedOrientations
=
"Portrait"
Orientation
=
"Portrait"
shell:SystemTray.IsVisible
=
"True"
>
<!--设置整个页面的上下文数据DataContext为RadiusViewModel-->
<
phone:PhoneApplicationPage.DataContext
>
<
my:RadiusViewModel
/>
</
phone:PhoneApplicationPage.DataContext
>
<
Grid
x:Name
=
"LayoutRoot"
Background
=
"Transparent"
>
<
Grid.RowDefinitions
>
<
RowDefinition
Height
=
"Auto"
/>
<
RowDefinition
Height
=
"*"
/>
</
Grid.RowDefinitions
>
<
StackPanel
x:Name
=
"TitlePanel"
Grid.Row
=
"0"
Margin
=
"12,17,0,28"
>
<
TextBlock
x:Name
=
"ApplicationTitle"
Text
=
"MY APPLICATION"
Style
=
"{StaticResource PhoneTextNormalStyle}"
/>
<
TextBlock
x:Name
=
"PageTitle"
Text
=
"Command"
Margin
=
"9,-7,0,0"
Style
=
"{StaticResource PhoneTextTitle1Style}"
/>
</
StackPanel
>
<
Grid
x:Name
=
"ContentPanel"
Grid.Row
=
"1"
Margin
=
"12,0,12,0"
>
<
Ellipse
Fill
=
"Red"
Height
=
"{Binding Radius}"
Width
=
"{Binding Radius}"
HorizontalAlignment
=
"Left"
Margin
=
"119,84,0,0"
Name
=
"ellipse1"
Stroke
=
"Black"
StrokeThickness
=
"1"
VerticalAlignment
=
"Top"
/>
<
Button
Content
=
"小"
Height
=
"72"
HorizontalAlignment
=
"Left"
Margin
=
"0,385,0,0"
Name
=
"button1"
VerticalAlignment
=
"Top"
Width
=
"160"
>
<
Custom:Interaction.Triggers
>
<
Custom:EventTrigger
EventName
=
"Click"
>
<
my_Interactivity:ExecuteCommandAction
CommandName
=
"MinRadius"
/>
</
Custom:EventTrigger
>
</
Custom:Interaction.Triggers
>
</
Button
>
<
Button
Content
=
"中"
Height
=
"72"
HorizontalAlignment
=
"Left"
Margin
=
"149,384,0,0"
Name
=
"button2"
VerticalAlignment
=
"Top"
Width
=
"160"
>
<
Custom:Interaction.Triggers
>
<
Custom:EventTrigger
EventName
=
"Click"
>
<
my_Interactivity:ExecuteCommandAction
CommandName
=
"MedRadius"
/>
</
Custom:EventTrigger
>
</
Custom:Interaction.Triggers
>
</
Button
>
<
Button
Content
=
"大"
Height
=
"72"
HorizontalAlignment
=
"Left"
Margin
=
"299,382,0,0"
Name
=
"button3"
VerticalAlignment
=
"Top"
Width
=
"160"
>
<
Custom:Interaction.Triggers
>
<
Custom:EventTrigger
EventName
=
"Click"
>
<
my_Interactivity:ExecuteCommandAction
CommandName
=
"MaxRadius"
/>
</
Custom:EventTrigger
>
</
Custom:Interaction.Triggers
>
</
Button
>
</
Grid
>
</
Grid
>
</
phone:PhoneApplicationPage
>
（2）RadiusViewModel.cs文件的代码,实现ViewModel层

view sourceprint?

using
System;
using
System.Windows.Input;
using
System.ComponentModel;
using
Microsoft.Expression.Interactivity.Core;
namespace
CommandDemo.ViewModel
{
public
class
RadiusViewModel : INotifyPropertyChanged
{
private
Double radius;
public
RadiusViewModel()
{
Radius = 0;
MinRadius =
new
ActionCommand(p =>Radius = 100);
MedRadius =
new
ActionCommand(p =>Radius = 200);
MaxRadius =
new
ActionCommand(p =>Radius = 300);
}
public
event
PropertyChangedEventHandler PropertyChanged;
public
ICommand MinRadius
{
get
;
private
set
;
}
public
ICommand MedRadius
{
get
;
private
set
;
}
public
ICommand MaxRadius
{
get
;
private
set
;
}
public
Double Radius
{
get
{
return
radius;
}
set
{
radius = value;
OnPropertyChanged(
"Radius"
);
}
}
protected
virtual
void
OnPropertyChanged(
string
propertyName)
{
var propertyChanged = PropertyChanged;
if
(propertyChanged !=
null
)
propertyChanged(
this
,
new
PropertyChangedEventArgs(propertyName));
}
}
}
（3）ExecuteCommandAction.cs类，实现Command操作

view sourceprint?

using
System;
using
System.Windows;
using
System.Windows.Input;
using
System.Windows.Interactivity;
using
System.Reflection;
namespace
CommandDemo.Command
{
public
class
ExecuteCommandAction : TriggerAction<FrameworkElement>
{
public
static
readonly
DependencyProperty CommandNameProperty =
DependencyProperty.Register(
"CommandName"
,
typeof
(
string
),
typeof
(ExecuteCommandAction),
null
);
public
static
readonly
DependencyProperty CommandParameterProperty =
DependencyProperty.Register(
"CommandParameter"
,
typeof
(
object
),
typeof
(ExecuteCommandAction),
null
);
protected
override
void
Invoke(
object
parameter)
{
if
(AssociatedObject ==
null
)
return
;
ICommand command =
null
;
var dataContext = AssociatedObject.DataContext;
foreach
(var info
in
dataContext.GetType().GetProperties(BindingFlags.Public | BindingFlags.Instance))
{
if
(IsCommandProperty(info)&& String.Equals(info.Name,CommandName,StringComparison.Ordinal))
{
command = (ICommand)info.GetValue(dataContext,
null
);
break
;
}
}
if
((command !=
null
)&& command.CanExecute(CommandParameter))
{
command.Execute(CommandParameter);
}
}
private
static
bool
IsCommandProperty(PropertyInfo property)
{
return
typeof
(ICommand).IsAssignableFrom(property.PropertyType);
}
public
string
CommandName
{
get
{
return
(
string
)GetValue(CommandNameProperty);
}
set
{
SetValue(CommandNameProperty,value);
}
}
public
object
CommandParameter
{
get
{
return
GetValue(CommandParameterProperty);
}
set
{
SetValue(CommandParameterProperty,value);
}
}
}
}
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