如下图是系统的结构图：这个示例是模仿计算器的MVVM模式的精简版，非常简单。
这篇文章就开门见山了，有关MVVM的理论部分，请参考MVVM设计模式
1、App中的代码：
public
App()
{
CalculatorView view =
new
CalculatorView();
view.DataContext =
new
CalculatorViewModel();
view.Show();
}
|
2、Model层中CauculatorModel的代码
class
CauculatorModel
{
public
string
FirstOperand {
get
;
set
; }
public
string
SecondOperand {
get
;
set
; }
public
string
Operation {
get
;
set
; }
public
string
Result {
get
;
set
; }
}
|
3、Command
public
class
DeletgateCommand<T>:ICommand
{
private
readonly
Action<T> _executeMethod =
null
;
private
readonly
Func<T,
bool
> _canExecuteMethod =
null
;
public
DeletgateCommand(Action<T> executeMethod)
:
this
(executeMethod,
null
)
{ }
public
DeletgateCommand(Action<T> executeMethod, Func<T,
bool
> canExecuteMethod)
{
if
(executeMethod ==
null
)
throw
new
ArgumentNullException(
"executeMetnod"
);
_executeMethod = executeMethod;
_canExecuteMethod = canExecuteMethod;
}
#region ICommand 成员
/// <summary>
/// Method to determine if the command can be executed
/// </summary>
public
bool
CanExecute(T parameter)
{
if
(_canExecuteMethod !=
null
)
{
return
_canExecuteMethod(parameter);
}
return
true
;
}
/// <summary>
/// Execution of the command
/// </summary>
public
void
Execute(T parameter)
{
if
(_executeMethod !=
null
)
{
_executeMethod(parameter);
}
}
#endregion
event
EventHandler ICommand.CanExecuteChanged
{
add { CommandManager.RequerySuggested += value; }
remove { CommandManager.RequerySuggested -= value; }
}
#region ICommand 成员
public
bool
CanExecute(
object
parameter)
{
if
(parameter ==
null
&&
typeof
(T).IsValueType)
{
return
(_canExecuteMethod ==
null
);
}
return
CanExecute((T)parameter);
}
public
void
Execute(
object
parameter)
{
Execute((T)parameter);
}
#endregion
}
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4、ViewModwl层，为了简化，此处Add方法采用硬编码的形式
public
class
CalculatorViewModel
{
CauculatorModel calculatorModel;
private
DeletgateCommand<
string
> addCommand;
public
CalculatorViewModel()
{
calculatorModel =
new
CauculatorModel();
}
#region Public Properties
public
string
FirstOperand
{
get
{
return
calculatorModel.FirstOperand; }
set
{ calculatorModel.FirstOperand = value; }
}
public
string
SecondOperand
{
get
{
return
calculatorModel.SecondOperand; }
set
{ calculatorModel.SecondOperand = value; }
}
public
string
Operation
{
get
{
return
calculatorModel.Operation; }
set
{ calculatorModel.Operation = value; }
}
public
string
Result
{
get
{
return
calculatorModel.Result; }
set
{ calculatorModel.Result = value; }
}
#endregion
public
ICommand AddCommand
{
get
{
if
(addCommand ==
null
)
{
addCommand =
new
DeletgateCommand<
string
>(Add, CanAdd);
}
return
addCommand;
}
}
public
void
Add(
string
x)
{
FirstOperand = x;
SecondOperand = x;
Result = (
double
.Parse(FirstOperand) +
double
.Parse(SecondOperand)).ToString();
Operation =
"+"
;
MessageBox.Show( FirstOperand+ Operation +SecondOperand +
"="
+ Result);
}
private
static
bool
CanAdd(
string
num)
{
return
true
;
}
}
|
ViewModelBase中的代码：
public
abstract
class
ViewModelBase : INotifyPropertyChanged
{
public
event
PropertyChangedEventHandler PropertyChanged;
protected
void
OnPropertyChanged(
string
propertyName)
{
PropertyChangedEventHandler handler = PropertyChanged;
if
(handler !=
null
)
{
handler(
this
,
new
PropertyChangedEventArgs(propertyName));
}
}
}
|
5、View层
<Grid>
<TextBox Height=
"23"
Margin=
"12,63,0,0"
Name=
"textBox1"
VerticalAlignment=
"Top"
HorizontalAlignment=
"Left"
Width=
"120"
/>
<Label Margin=
"12,25,95,0"
Name=
"label2"
Height=
"32"
VerticalAlignment=
"Top"
>请输入x的值！ x+x=? </Label>
<Button Height=
"23"
Command=
"{Binding AddCommand}"
CommandParameter=
"{Binding ElementName=textBox1,Path=Text}"
HorizontalAlignment=
"Left"
Margin=
"12,102,0,0"
Name=
"button1"
VerticalAlignment=
"Top"
Width=
"75"
>
确定</Button>
</Grid>
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CommandParameter里传递的是一个参数，当然可以传递多个参数。
6、效果图：
参考资料：MVVM的一个Example
本文转自Work Hard Work Smart博客园博客，原文链接：http://www.cnblogs.com/linlf03/archive/2011/09/11/2173833.html，如需转载请自行联系原作者
