这是我辅导的一个项目开发中的例子，他们是用WPF做界面开发，在学习了如何使用MVVM来实现界面与逻辑的分离，并且很好的数据更新之后，有一个疑问就是，这种双向的数据更新确实很不错，但如果我们希望用户可以撤销修改怎么办呢？其实这个功能，很早就有，甚至在原先的Windows Forms里面也可以实现。秘密就是实现IEditableObject这个接口。
关于这个接口的官方文档在这里：http://msdn.microsoft.com/zh-cn/library/vstudio/system.componentmodel.ieditableobject.aspx
我做了一个小的例子，帮助大家来理解。该例子使用了MVVM这种设计模式，如果你对此不熟悉，请先参考：http://www.cnblogs.com/chenxizhang/archive/2011/10/01/2197786.html
这个例子，你可以通过 http://files.cnblogs.com/chenxizhang/WpfApplicationBindingSample.zip 进行下载
Model：Employee
using System.ComponentModel; namespace WpfApplicationBindingSample.Models
{
/// <summary>
/// 业务实体(Business Entity)
/// </summary>
class Employee : INotifyPropertyChanged,IEditableObject
{
private string _firstName; public string FirstName
{
get { return _firstName; }
set
{
if (_firstName != value)
{
_firstName = value;
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs("FirstName"));
PropertyChanged(this, new PropertyChangedEventArgs("FullName"));
}
}
}
} private string _lastName;
public string LastName
{
get { return _lastName; }
set
{
if (_lastName != value)
{
_lastName = value;
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs("LastName"));
PropertyChanged(this, new PropertyChangedEventArgs("FullName"));
}
}
}
} public string FullName
{
get
{
return FirstName + "," + LastName;
}
} public event PropertyChangedEventHandler PropertyChanged; private Employee backup;//用这个字段来保存一个备份数据
public void BeginEdit()
{
//开始编辑，此时将当前的状态保存起来，以便后续可以根据情况提交或者撤销更改
backup = this.MemberwiseClone() as Employee;//通过克隆的方式直接地复制一份数据
} public void CancelEdit()
{
//撤销编辑，此时将对象状态恢复到备份的状态
this.FirstName = backup.FirstName;
this.LastName = backup.LastName;
} public void EndEdit()
{
//结束编辑，这里可以不做任何事情，也可以添加一些额外的逻辑
}
}
}
.csharpcode, .csharpcode pre
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ViewModel:
using GalaSoft.MvvmLight;
using GalaSoft.MvvmLight.Command;
using System.Windows;
using WpfApplicationBindingSample.Models; namespace WpfApplicationBindingSample.ViewModels
{
/// <summary>
/// 视图模型：专门用来为界面（视图）来服务的，这里用来包含一些业务逻辑
/// </summary>
class MainWindowViewModel : ViewModelBase
{ public MainWindowViewModel()
{
CurrentEmployee = new Employee()
{
FirstName = "ares",
LastName = "chen"
};
} public Employee CurrentEmployee { get; set; }
public RelayCommand EditCommand {
get {
return new RelayCommand(() => {
//将该员工设置为开始编辑
CurrentEmployee.BeginEdit();
});
}
} /// <summary>
/// 使用命令的机制代替了事件
/// </summary>
public RelayCommand SubmitCommand
{
get
{//使用匿名方法
return new RelayCommand(() =>
{
//结束编辑，让更改生效
CurrentEmployee.EndEdit(); MessageBox.Show(CurrentEmployee.FullName);
});
}
} public RelayCommand CancelCommand
{
get
{
return new RelayCommand(() =>
{
CurrentEmployee.CancelEdit();//取消编辑，此时可以看到FullName那个标签的文本恢复到原来的值
});
}
}
}
}
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font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
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width: 100%;
margin: 0em;
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.csharpcode .lnum { color: #606060; }
View:
<Window x:Class="WpfApplicationBindingSample.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:vm="clr-namespace:WpfApplicationBindingSample.ViewModels"
Title="MainWindow"
Height="350"
Width="525"> <Window.DataContext>
<!--绑定数据上下文-->
<vm:MainWindowViewModel></vm:MainWindowViewModel>
</Window.DataContext> <Window.Resources>
<Style TargetType="TextBlock">
<Setter Property="Margin"
Value="3"></Setter>
</Style> <Style TargetType="TextBox">
<Setter Property="Width"
Value="200"></Setter>
<Setter Property="HorizontalAlignment"
Value="Left"></Setter>
</Style> <Style TargetType="Button">
<Setter Property="Width"
Value="100"></Setter>
<Setter Property="HorizontalAlignment"
Value="Left"></Setter>
</Style> </Window.Resources> <StackPanel Margin="10">
<TextBlock FontSize="30"
Text="编辑员工"></TextBlock> <TextBlock Text="姓氏"></TextBlock>
<TextBox Text="{Binding CurrentEmployee.FirstName,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"></TextBox>
<!--匈牙利命名法-->
<TextBlock Text="名称"></TextBlock>
<TextBox Text="{Binding CurrentEmployee.LastName,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"></TextBox> <TextBlock Text="全称"></TextBlock>
<TextBlock Text="{Binding CurrentEmployee.FullName}"></TextBlock> <Button Content="编辑"
Command="{Binding EditCommand}"></Button>
<Button Content="提交"
Command="{Binding SubmitCommand}"></Button>
<Button Content="取消"
Command="{Binding CancelCommand}"></Button> </StackPanel> </Window>