事件处理程序的处理顺序问题

[HostProtection(SecurityAction.LinkDemand,SharedState=true)]
publicsealedclassEventHandlerList:IDisposable
{
//Fields
privateListEntryhead;
privateComponentparent;

//Methods
publicEventHandlerList()
{
}

internalEventHandlerList(Componentparent)
{
this.parent=parent;
}

publicvoidAddHandler(objectkey,Delegatevalue)
{
ListEntryentry=this.Find(key);
if(entry!=null)
{
entry.handler=Delegate.Combine(entry.handler,value);//这里的关键在于Delegate.Combine，所以根据注册顺序不一样，是一个顺序型的组合
}
else
{
this.head=newListEntry(key,value,this.head);
}
}

publicvoidAddHandlers(EventHandlerListlistToAddFrom)
{
for(ListEntryentry=listToAddFrom.head;entry!=null;entry=entry.next)
{
this.AddHandler(entry.key,entry.handler);
}
}

publicvoidDispose()
{
this.head=null;
}

privateListEntryFind(objectkey)
{
ListEntryhead=this.head;
while(head!=null)
{
if(head.key==key)
{
returnhead;
}
head=head.next;
}
returnhead;
}

publicvoidRemoveHandler(objectkey,Delegatevalue)
{
ListEntryentry=this.Find(key);
if(entry!=null)
{
entry.handler=Delegate.Remove(entry.handler,value);
}
}

//Properties
publicDelegatethis[objectkey]
{
get
{
ListEntryentry=null;
if((this.parent==null)||this.parent.CanRaiseEventsInternal)
{
entry=this.Find(key);
}
if(entry!=null)
{
returnentry.handler;
}
returnnull;
}
set
{
ListEntryentry=this.Find(key);
if(entry!=null)
{
entry.handler=value;
}
else
{
this.head=newListEntry(key,value,this.head);
}
}
}

//NestedTypes
privatesealedclassListEntry
{
//Fields
internalDelegatehandler;
internalobjectkey;
internalEventHandlerList.ListEntrynext;

//Methods
publicListEntry(objectkey,Delegatehandler,EventHandlerList.ListEntrynext)
{
this.next=next;
this.key=key;
this.handler=handler;
}
}
}

所以,既然是通过线性表来保存的，那么就有一个先后顺序的情况。其实，一个更好的写法是下面这样的

usingSystem;
usingSystem.Collections.Generic;
usingSystem.Linq;
usingSystem.Text;
usingSystem.Reflection;

usingSystem.Threading;
usingSystem.ComponentModel;
namespaceConsoleApplication1
{
classProgram
{
staticvoidMain(string[]args)
{
///这个例子解释了如果为一个事件绑定了多个事件处理程序，那么他们处理的顺序与绑定顺序是一致的

Console.WriteLine("主线程号是:{0}",Thread.CurrentThread.ManagedThreadId);

Employeee=newEmployee();
e.NameChanged+=newEventHandler(e_NameChanged);
e.NameChanged+=newEventHandler(e_NameChanged2);

e.Name="areschen";

Console.Read();
}

staticvoide_NameChanged2(objectsender,EventArgse)
{

Console.WriteLine("第2个事件处理程序触发的时间是:{0}",DateTime.Now);
Console.WriteLine("当前线程号是:{0}",Thread.CurrentThread.ManagedThreadId);
}

staticvoide_NameChanged(objectsender,EventArgse)
{
Console.WriteLine("第1个事件处理程序触发的时间是:{0}",DateTime.Now);
Console.WriteLine("当前线程号是:{0}",Thread.CurrentThread.ManagedThreadId);
}
}

classEmployee
{
//publiceventEventHandlerNameChanged;

protectedEventHandlerListlistEventDelegates=newEventHandlerList();
privateobjectNameChangedEventKey=newobject();

publiceventEventHandlerNameChanged{
add{
listEventDelegates.AddHandler(NameChangedEventKey,value);
}
remove{
listEventDelegates.RemoveHandler(NameChangedEventKey,value);
}
}

privatestringname;
publicstringName
{
get
{
returnname;
}
set
{
name=value;

if(listEventDelegates[NameChangedEventKey]!=null){
listEventDelegates[NameChangedEventKey].DynamicInvoke(newobject[]{this,null});
}
}
}
}
}