1. MVVM介绍：
MVVM就是: Model -- 模型（现实中对象的抽象）
View -- UI（用户界面）
ViewModel -- UI界面的抽象（给View提供数据，并响应View的操作）
2. 关键是要能准确的进行ViewModel的建模,处理好View与ViewModel之间的关系
2.1. 只有2种关系：
数据传递 --- 双向，使用Binding实现；
操作传递 --- 单向（只从View传递给ViewModel），使用命令Command实现；
3. 开始
3.1. 首先创建NotificationObject,它是所以ViewModel的基类
因为要使用Binding，而ViewModel就充当数据源的角色，而要实现当值有变化时会自动响应，就必须实现INotifyPropertyChanged接口，代码如下：
1 using System;
2 using System.Collections.Generic;
3 using System.ComponentModel;
4 using System.Linq;
5 using System.Text;
6 using System.Threading.Tasks;
7
8 namespace MVVMTest.ViewModels
9 {
10 public class NotificationObject:INotifyPropertyChanged
11 {
12 public event PropertyChangedEventHandler PropertyChanged;
13
14 public void RaisePropertyChanged(string property)
15 {
16 if (this.PropertyChanged != null)
17 this.PropertyChanged.Invoke(this, new PropertyChangedEventArgs(property));
18
19 }
20 }
21 }
3.2.接着要创建DelegateCommand，实现了ICommand接口，用来处理View发送到ViewModel的命令，代码如下：
1 using System;
2 using System.Collections.Generic;
3 using System.Linq;
4 using System.Text;
5 using System.Threading.Tasks;
6 using System.Windows.Input;
7
8 namespace MVVMTest.Commands
9 {
10 public class DelegateCommand:ICommand
11 {
12 public bool CanExecute(object parameter)
13 {
14 if (this.CanExecuteFunc == null)
15 {
16 return true;
17 }
18
19 return this.CanExecuteFunc(parameter);
20 }
21
22 public event EventHandler CanExecuteChanged;
23
24 public void Execute(object parameter)
25 {
26 if (this.ExecuteAction == null)
27 {
28 return;
29 }
30 this.ExecuteAction(parameter);
31 }
32
33 public Action<object> ExecuteAction { get; set; }
34 public Func<object, bool> CanExecuteFunc { get; set; }
35 }
36 }
3.3.为了方便开发，这里推荐自定义一个code snippet(代码块)：
放到此目录下C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC#\Snippets\1033\Visual C#
1 <?xml version="1.0" encoding="utf-8" ?>
2 <CodeSnippets xmlns="http://schemas.microsoft.com/VisualStudio/2005/CodeSnippet">
3 <CodeSnippet Format="1.0.0">
4 <Header>
5 <Title>propn</Title>
6 <Shortcut>propn</Shortcut>
7 <Description>Code snippet for NotificationObject property and backing field</Description>
8 <Author>Microsoft Corporation</Author>
9 <SnippetTypes>
10 <SnippetType>Expansion</SnippetType>
11 </SnippetTypes>
12 </Header>
13 <Snippet>
14 <Declarations>
15 <Literal>
16 <ID>type</ID>
17 <ToolTip>Property type</ToolTip>
18 <Default>int</Default>
19 </Literal>
20 <Literal>
21 <ID>property</ID>
22 <ToolTip>Property name</ToolTip>
23 <Default>MyProperty</Default>
24 </Literal>
25 <Literal>
26 <ID>field</ID>
27 <ToolTip>The variable backing this property</ToolTip>
28 <Default>myVar</Default>
29 </Literal>
30 </Declarations>
31 <Code Language="csharp"><![CDATA[private $type$ $field$;
32
33 public $type$ $property$
34 {
35 get { return $field$;}
36 set {
37 $field$ = value;
38 this.RaisePropertyChanged("$property$");
39 }
40 }
41 $end$]]>
42 </Code>
43 </Snippet>
44 </CodeSnippet>
45 </CodeSnippets>
3.4. 由于这个例子较简单，所以没有设计到Model的设计，而直接到ViewModel的设计，一般的规则是每个View就有一个对应的ViewModel，而ViewModel是充当View的数据源的，所以只需要考虑View需要什么数据、含有哪些操作，创建MainWindow的ViewModel，MainWindowViewModel,代码如下：
1 using MVVMTest.Commands;
2 using System;
3 using System.Collections.Generic;
4 using System.Linq;
5 using System.Text;
6 using System.Threading.Tasks;
7
8 namespace MVVMTest.ViewModels
9 {
10 public class MainWindowViewModel:NotificationObject
11 {
12 private string txt1;
13
14 public string Txt1
15 {
16 get { return txt1; }
17 set
18 {
19 txt1 = value;
20 this.RaisePropertyChanged("Txt1");
21 }
22 }
23
24 private string txt2;
25
26 public string Txt2
27 {
28 get { return txt2; }
29 set
30 {
31 txt2 = value;
32 this.RaisePropertyChanged("Txt2");
33 }
34 }
35
36 private string result;
37
38 public string Result
39 {
40 get { return result; }
41 set
42 {
43 result = value;
44 this.RaisePropertyChanged("Result");
45 }
46 }
47
48 public DelegateCommand ConcatCommand { get; set; }
49 public void Concat(object parameter)
50 {
51 Result = Txt1 + " and " + Txt2;
52 }
53
54
55 public MainWindowViewModel()
56 {
57 ConcatCommand = new DelegateCommand();
58 ConcatCommand.ExecuteAction = new Action<object>(Concat);
59 }
60
61
62
63 }
64 }
3.4.将ViewModel作为数据源赋值给View的DataContext
1 using MVVMTest.ViewModels;
2 using System;
3 using System.Collections.Generic;
4 using System.Linq;
5 using System.Text;
6 using System.Threading.Tasks;
7 using System.Windows;
8 using System.Windows.Controls;
9 using System.Windows.Data;
10 using System.Windows.Documents;
11 using System.Windows.Input;
12 using System.Windows.Media;
13 using System.Windows.Media.Imaging;
14 using System.Windows.Navigation;
15 using System.Windows.Shapes;
16
17 namespace MVVMTest
18 {
19 /// <summary>
20 /// Interaction logic for MainWindow.xaml
21 /// </summary>
22 public partial class MainWindow : Window
23 {
24 public MainWindow()
25 {
26 InitializeComponent();
27 this.DataContext = new MainWindowViewModel();
28 }
29 }
30 }
3.5.在View中绑定数据：
1 <Window x:Class="MVVMTest.MainWindow"
2 xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
3 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
4 Title="MainWindow" Height="350" Width="525">
5 <Grid>
6 <TextBox Margin="40,51,311,216" Text="{Binding Txt1}"/>
7 <TextBox Margin="230,51,114,216" Text="{Binding Txt2}"/>
8 <TextBox Margin="128,152,176,139" Text="{Binding Result}"/>
9 <Button Margin="313,241,64,23" Command="{Binding ConcatCommand}"/>
10 </Grid>
11 </Window>
源代码：http://yunpan.cn/c3c7AAXm4U2dP 访问密码 8788
时间： 2024-10-14 05:19:38