參考:http://caliburn.codeplex.com/wikipage?title=Command%20Basics&referringTitle=Documentation??

command在wpf的viewmodel中使用的非常的廣泛,討論的也非常多.

來看下caliburn對command的支持

caliburn支持三種方式command的注冊

• 容器
• 資源
• 綁定

Command解析字符串

parser.RegisterMessageParser("ResourceCommand", new CommandMessageParser(binder, CommandSource.Resource)); parser.RegisterMessageParser("ContainerCommand", new CommandMessageParser(binder, CommandSource.Container)); parser.RegisterMessageParser("BoundCommand", new CommandMessageParser(binder, CommandSource.Bound));

為簡化xaml,在Attach中采用了特定解析的字符串,下面可以看到

1.使用容器

首先定義一個對象

注意點:

掛上Command標簽

方法必須為Execute和CanExecute

[Command] public class ShowMessageCommand {//Note: A command must have an entry point. A method named 'Execute' is searched for by default. //Note: Use the CommandAttribute.ExecuteMethod to specify a different method.//Note: The 'Execute' method inherits all the features available to actions.public void Execute(string message){MessageBox.Show(message);}//NOTE: This is picked up automatically by the ActionFactory based on its naming convention.public bool CanExecute(string message){return !string.IsNullOrEmpty(message);} }

xaml

<Button Content="Attached Container Command w/ 1 Parameter" cal:Message.Attach="ContainerCommand ShowMessage(message.Text)"/>

注意xaml使用方式,ContainerCommand為特定的解析字符串ShowMessage則代表ShowMessageCommand,以下規則是一樣的

2.使用資源

首先然后定義對象,注意Preview標簽

public class ShowTitledMessageCommand {//Note: A command must have a method named 'Execute'//Note: The 'Execute' method inherits all the features available to actions.[Preview("CanExecute")]public void Execute(string title, string message){MessageBox.Show(message, title);}public bool CanExecute(string title, string message){return !string.IsNullOrEmpty(title) && !string.IsNullOrEmpty(message);} }

定義資源

<Window.Resources><!--Note: Adding a command to resources.--><local:ShowTitledMessageCommand x:Key="ShowTitledMessage" /> </Window.Resources>

xaml引用

<Button Content="Attached Resource Command w/ 2 Parameters"cal:Message.Attach="ResourceCommand ShowTitledMessage(title.Text, message.Text)" />

3.使用綁定

要綁定的前提是需要有源

首先要定義源

<Window.DataContext><!--Note: Makes the presentation model available for binding through the data context.--><local:MyModel /> </Window.DataContext>

使用BoundCommand綁定

<TextBox x:Name="message" /><!--Note: Executes the command located through data binding. The framework infers the trigger type.--> <Button Content="Click Me!"cal:Message.Attach="BoundCommand TheCommand(message.Text)" />

我們通過代碼來看下不同的解析過程

protected override void SetCore(CommandMessage message, DependencyObject target, string coreOfMessage){switch(_commandSource){case CommandSource.Resource:var frameworkElement = target as FrameworkElement;if(frameworkElement != null){frameworkElement.Loaded +=delegate { message.Command = frameworkElement.GetResource<object>(coreOfMessage); };} break;case CommandSource.Container:message.Command = ServiceLocator.Current.GetInstance(null, coreOfMessage);break;case CommandSource.Bound:var binding = new Binding(coreOfMessage);BindingOperations.SetBinding(message, CommandMessage.CommandProperty, binding); break;default:throw new NotSupportedException(_commandSource + " is not a supported command source.");}}

實質上是非常簡單的,主要手段還是通過給CommandMessage的Command賦值,方式不同而已.以上三種方式一比較，第一種是最簡單的,這也是依賴注入帶來的好處,不需要事先顯示聲明對象.效果都是一樣的

來看下原始的用法

<Button Content="Triggers: Container Command With 1 Explicit Parameters"><cal:Message.Triggers><cal:RoutedMessageTriggerCollection><cal:EventMessageTrigger EventName="Click"><cal:EventMessageTrigger.Message><!--Note ResolveExtension doesn't exist in Silverlight, but you can auto resolve by string key. See SL samples.--><cal:CommandMessage Command="{cal:Resolve Key=ShowMessage}"><!--Note: The declaration of parameters is different from Silverlight.--><cal:Parameter Value="{Binding ElementName=message, Path=Text}"/></cal:CommandMessage></cal:EventMessageTrigger.Message></cal:EventMessageTrigger></cal:RoutedMessageTriggerCollection></cal:Message.Triggers> </Button>

轉載于:https://www.cnblogs.com/Clingingboy/archive/2009/12/29/1634712.html

總結

以上是生活随笔為你收集整理的Caliburn笔记-基本Command(wpf框架)的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。