Simple MVVM Toolkit 之 Messaging（B）发送消息，并接收回调

继续上一篇《Simple MVVM Toolkit 之 Messaging（A）》。

接下来使用Messaging实现客户列表View-Model和客户明细View-Model之间的通讯。

1. 为 Messaging 准备辅助类和窗体：

1.1 右键Models文件夹，添加类 MessageTokens，此类目的是提供一个消息标识符。

1.2 右键Models文件夹，添加类 IncreaseInfo，此类是一个增量信息的实体。

 1     public class IncreaseInfo
 2     {
 3         public IncreaseInfo()
 4         { }
 5 
 6         public IncreaseInfo(string customerName, int age)
 7         {
 8             // TODO: Complete member initialization
 9             this.CustomerName = customerName;
10             this.Age = age;
11         }
12 
13         public string CustomerName { get; set; }
14 
15         public int Age { get; set; }
16     }

 

1.3 右键Models文件夹，添加类 ApprovalInfo，此类表示的是弹出提示窗口的消息实体。

 1     public class ApprovalInfo
 2     {
 3         public ApprovalInfo()
 4         { }
 5 
 6         public ApprovalInfo(string customerName, int age, bool result)
 7         {
 8             this.CustomerName = customerName;
 9             this.Age = age;
10             this.Result = result;
11         }
12 
13         public string CustomerName { get; set; }
14 
15         public int Age { get; set; }
16 
17         public bool Result { get; set; }
18     }

 

1.4 右键Views文件夹，添加窗体 ApprovalIncrease，此窗体是一个提示框。

 1 <Window x:Class="MessagingSimple.Views.ApprovalIncrease"
 2         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
 3         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
 4         Title="ApproveIncrease" Height="174" Width="352">
 5     <Grid>
 6         <Grid.RowDefinitions>
 7             <RowDefinition Height="81*" />
 8             <RowDefinition Height="54*" />
 9         </Grid.RowDefinitions>
10         
11         <StackPanel Orientation="Horizontal">
12             <StackPanel.Resources>
13                 <Style TargetType="TextBlock">
14                     <Setter Property="VerticalAlignment" Value="Center" />
15                 </Style>
16             </StackPanel.Resources>
17             <TextBlock Text="Do you approve the increase of " />
18             <TextBlock Name="quantityText" />
19             <TextBlock Text=" for " />
20             <TextBlock Name="customerText" />
21             <TextBlock Text="?" />
22         </StackPanel>
23         <Button Content="No"
24                 Height="23"
25                 HorizontalAlignment="Left"
26                 Margin="202,12,0,0"
27                 Name="btnNo"
28                 VerticalAlignment="Top"
29                 Width="75"
30                 Click="btnNo_Click"
31                 Grid.Row="1" />
32         <Button Content="Yes"
33                 Height="23"
34                 HorizontalAlignment="Left"
35                 Margin="73,12,0,0"
36                 Name="btnYes"
37                 VerticalAlignment="Top"
38                 Width="75"
39                 Click="btnYes_Click"
40                 Grid.Row="1" />
41     </Grid>
42 </Window>

 1     /// <summary>
 2     /// ApproveIncrease.xaml 的交互逻辑
 3     /// </summary>
 4     public partial class ApprovalIncrease : Window
 5     {
 6         public ApprovalIncrease()
 7         {
 8             InitializeComponent();
 9         }
10         public ApprovalIncrease(IncreaseInfo increaseInfo)
11             : this()
12         {
13             this.quantityText.Text = increaseInfo.Age.ToString();
14             this.customerText.Text = increaseInfo.CustomerName;
15         }
16 
17         private void btnYes_Click(object sender, RoutedEventArgs e)
18         {
19             this.DialogResult = true;
20         }
21 
22         private void btnNo_Click(object sender, RoutedEventArgs e)
23         {
24             this.DialogResult = false;
25         }
26 
27 
28 
29 
30     }

 

2 在Views-CustomerList.xaml中增加按钮和消息栏。

 1         <Button Content="Increase Age"
 2                 Height="23"
 3                 Grid.Row="1"
 4                 HorizontalAlignment="Center"
 5                 Command="{Binding Path=IncreaseAgeCommand}"
 6                 VerticalAlignment="Center"
 7                 Width="120"
 8                 Margin="0,21,0,81" />
 9         <TextBlock Grid.Row="1"
10                    Height="42"
11                    HorizontalAlignment="Center"
12                    Margin="0,61,0,0"
13                    Name="textBlock1"
14                    Text="{Binding Path=MessageText}"
15                    VerticalAlignment="Top"
16                    Width="245" />

 

3 实现 Messaging 通讯五步骤：

3.1 第一步：定义通讯标识。（MessageTokens.cs）

1         //Step 1 定义增长年龄标识。
2         public const string IncreaseAge = "AgeIncreaseToken";

 

3.2 第二步：当年龄增加之后获取通知的Register。(CustomerDetailViewModel.cs)

1             //Step 2 当年龄增加之后获取通知的Register。
2             RegisterToReceiveMessages<IncreaseInfo, ApprovalInfo>(
3                 MessageTokens.IncreaseAge, OnOrdersIncrease);

 

3.3 第三步：处理客户列表年龄增加的通知消息。(CustomerDetailViewModel.cs)

 1         //Step 3 处理客户列表年龄增加的通知消息。
 2         private void OnOrdersIncrease(object sender, NotificationEventArgs
 3            <IncreaseInfo, ApprovalInfo> e)
 4         {
 5             if (e.Data.CustomerName != Customer.CustomerName)
 6                 return;
 7             ApprovalIncrease approvalIncrease = new ApprovalIncrease(e.Data);
 8 
 9             approvalIncrease.Closed += (s, ea) =>
10             {
11                 ApprovalInfo approvalInfo = new ApprovalInfo(
12                     Customer.CustomerName,
13                     e.Data.Age,
14                     (bool)approvalIncrease.DialogResult);
15 
16                 e.Completed(approvalInfo);
17             };
18 
19             approvalIncrease.ShowDialog();
20         }

 

3.4 第四步：发送消息。(CustomerListViewModel.cs)

1             //Step 4
2             SendMessage(MessageTokens.IncreaseAge,
3                 new NotificationEventArgs<IncreaseInfo, ApprovalInfo>(
4                     null, increaseInfo, OnIncreaseResponse));

 

3.5 第五步：处理通知回调。

 1         //Step 5 处理通知回调。
 2         void OnIncreaseResponse(ApprovalInfo approve)
 3         {
 4             string resultText = approve.Result ? "approved" : "rejected";
 5             MessageText = string.Format(
 6                 "Age quantity of {0} {1} for {2}",
 7                 approve.Age, resultText, approve.CustomerName);
 8 
 9             if (!approve.Result)
10             {
11                 SelectedCustomer.Age -= 1;
12             }
13         }

流程如下：

运行效果如下。

点击这里下载源代码。(MessagingSimple-MessagingEnd)