今天 说一下Caliburn.Micro的IEventAggregator和IHandle<T>分成两篇去讲这一篇写一个简单的例子
看一它的的实现和源码
下一篇用它们做一个多语言的demo
这两个是事件的订阅和广播，很强大，但用的时候要小心发生不必要的冲突。
先看一下它的实现思想
在Caliburn.Micro里EventAggregator要以单例的形式出现这样可以做到对广播做到统一的管理
对象实现IHand<T>接口后通过EventAggregator的subsribe方法把自己加入到Handler集合中这样就能接叫信息
能过EventAggregator.Publish(object obj)方法去发送广播
源码：
先看一下个小demo再去分析它的源码是怎么实现的
效果
先写一个消息类，这个类只是做一个IHandle<T>的类型应用没有什么实际意义
class MyMessage { public string Str { get; set; } public override string ToString() { return Str; } } 建一个窗体MainView和一个ViewModel类
窗体有一个textBox显示消息。一个button打开窗体一个发布消息
再看一下ViewModel实现 了两个IHandle<T> 一个是string 类型一个是我们自己定义的MyMessage
MainViewMode发布string类型的广播也接收string类型和MyMessage类型的消息
[Export(typeof(IShell))] class MyMainViewModel : PropertyChangedBase, IHandle,IHandle { readonly IEventAggregator _events; readonly IWindowManager _windowManager; string strMessage; public string StrMessage { get { return strMessage; } set { strMessage = value; NotifyOfPropertyChange(() => StrMessage); } } [ImportingConstructor] public MyMainViewModel(IEventAggregator e,IWindowManager win) { _events = e; _events.Subscribe(this); _windowManager = win; } public void Handle(string message) { StrMessage = message; } public void Handle(MyMessage message) { StrMessage = message.ToString(); } #region public void Publish() { _events.Publish(StrMessage); } #endregion #region 打开窗体 public void OpenOneWin() { OneCViewModel _one=new OneCViewModel(); _windowManager.ShowWindow(_one); } #endregion
再建一个窗体做接收和广播
它只接收string类型的消息和发布MyMessage类型的消息
1
using Caliburn.Micro;using CaliburnIHandle.CommonC;using System;using System.Collections.Generic;using System.ComponentModel.Composition;using System.Linq;using System.Text;namespace CaliburnIHandle.MyViewModels{ [Export(typeof(OneCViewModel))] class OneCViewModel : PropertyChangedBase, IHandle { readonly IEventAggregator _event; string oneMessage; public string OneMessage { get { return oneMessage; } set { oneMessage = value; NotifyOfPropertyChange(() => OneMessage); } } public OneCViewModel() { _event = IoC.Get (); _event.Subscribe(this); } public void OnePublish() { _event.Publish(new MyMessage { Str = OneMessage + " One!" }); } public void Handle(string message) { OneMessage = message; } }}
看一下IHandle<T>接口
public interface IHandle: IHandle { //don't use contravariance here /// /// Handles the message. /// /// The message. void Handle(TMessage message); }
EventAggregator类通过
////// Subscribes an instance to all events declared through implementations of /// The instance to subscribe for event publication. public virtual void Subscribe(object subscriber) { if (subscriber == null) { throw new ArgumentNullException("subscriber"); } lock(handlers) { if (handlers.Any(x => x.Matches(subscriber))) { return; } handlers.Add(new Handler(subscriber)); } }///
把订阅的类放到Handlers集合里
再通过Publish发布相应的消息
////// Publishes a message. /// /// The message instance. ////// Does not marshall the the publication to any special thread by default. /// public virtual void Publish(object message) { if (message == null) { throw new ArgumentNullException("message"); } Publish(message, PublicationThreadMarshaller); } ////// Publishes a message. /// /// The message instance. /// Allows the publisher to provide a custom thread marshaller for the message publication. public virtual void Publish(object message, Actionmarshal) { if (message == null){ throw new ArgumentNullException("message"); } if (marshal == null) { throw new ArgumentNullException("marshal"); } Handler[] toNotify; lock (handlers) { toNotify = handlers.ToArray(); } marshal(() => { var messageType = message.GetType(); var dead = toNotify .Where(handler => !handler.Handle(messageType, message)) .ToList(); if(dead.Any()) { lock(handlers) { dead.Apply(x => handlers.Remove(x)); } } }); }