Prism应用开发（八）——松耦合组件之间通信

一、Commands

创建一个全局的command，该command将会在各个组件之间共享。

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public static class GlobalCommands  
{  
public static CompositeCommand MyCompositeCommand = new CompositeCommand();  
}  

public static class GlobalCommands
{
public static CompositeCommand MyCompositeCommand = new CompositeCommand();
}

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GlobalCommands.MyCompositeCommand.RegisterCommand(command1);  
GlobalCommands.MyCompositeCommand.RegisterCommand(command2);  

GlobalCommands.MyCompositeCommand.RegisterCommand(command1);
GlobalCommands.MyCompositeCommand.RegisterCommand(command2);

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<Button Name="MyCompositeCommandButton" Command="{x:Static  
local:GlobalCommands.MyCompositeCommand}">Execute My Composite Command </Button>  

<Button Name="MyCompositeCommandButton" Command="{x:Static
local:GlobalCommands.MyCompositeCommand}">Execute My Composite Command </Button>

二、Shared Service

module之间可以通过Shared Service相互通信而不用直接引用另一个module。

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protected void RegisterViewsAndServices()  
{  
_container.RegisterType<IMarketFeedService, MarketFeedService>(new  
ContainerControlledLifetimeManager());  
//...  
}  

protected void RegisterViewsAndServices()
{
_container.RegisterType<IMarketFeedService, MarketFeedService>(new
ContainerControlledLifetimeManager());
//...
}

三、Event Aggregation

Prism提供了为松耦合组件之间通信提供了事件的机制。这个机制基于event aggregator service。允许发布和订阅事件而不用使得各个module引用对方。

下面的代码用户创建，发布和订阅事件

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public class TickerSymbolSelectedEvent : CompositePresentationEvent<string>{}  

public class TickerSymbolSelectedEvent : CompositePresentationEvent<string>{}

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this.eventAggregator.GetEvent<TickerSymbolSelectedEvent>().Publish("STOCK0");  

this.eventAggregator.GetEvent<TickerSymbolSelectedEvent>().Publish("STOCK0");

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public void Run()  
{  
...  
this.eventAggregator.GetEvent<TickerSymbolSelectedEvent>().Subscribe(ShowNews,  
ThreadOption.UIThread);  
);  
}  
public void ShowNews(string companySymbol)  
{  
this.articlePresentationModel.SetTickerSymbol(companySymbol);  
}  

public void Run()
{
...
this.eventAggregator.GetEvent<TickerSymbolSelectedEvent>().Subscribe(ShowNews,
ThreadOption.UIThread);
);
}
public void ShowNews(string companySymbol)
{
this.articlePresentationModel.SetTickerSymbol(companySymbol);
}

subscribe还提供了用于过滤的参数，例如：

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FundAddedEvent fundAddedEvent = this.eventAggregator.GetEvent<FundAddedEvent>();  
fundAddedEvent.Subscribe(FundAddedEventHandler, ThreadOption.UIThread, false,  
fundOrder => fundOrder.CustomerId == this.customerId);