第一起來學習C#的觀察者模式BaggageHandlerprovider=newBaggageHandler();

ArrivalsMonitorobserver1=newArrivalsMonitor("BaggageClaimMonitor1");

ArrivalsMonitorobserver2=newArrivalsMonitor("SecurityExit");

//添加信息，此時沒有觀察者，對于新的信息不會進行操作，若有觀察者，則對觀察者內部數據進行對比，若有新內容則進行更新。

provider.BaggageStatus(712,"Detroit",3);

//添加了觀察者，觀察者內部也有數據集。新信息傳進來，會與內部數據集進行對比，若有新內容則進行更新。

observer1.Subscribe(provider);

provider.BaggageStatus(712,"Kalamazoo",3);

provider.BaggageStatus(400,"NewYork-Kennedy",1);

provider.BaggageStatus(712,"Detroit",3);

observer2.Subscribe(provider);

provider.BaggageStatus(511,"SanFrancisco",2);

//參數3為0執行移除712對應信息值，對應觀察者打印

provider.BaggageStatus(712);

observer2.Unsubscribe();

provider.BaggageStatus(400);

provider.LastBaggageClaimed();

//Theexampledisplaysthefollowingoutput:

//ArrivalsinformationfromBaggageClaimMonitor1

//Detroit7123

//ArrivalsinformationfromBaggageClaimMonitor1

//Detroit7123

//Kalamazoo7123

//ArrivalsinformationfromBaggageClaimMonitor1

//Detroit7123

//Kalamazoo7123

//NewYork-Kennedy4001

//ArrivalsinformationfromSecurityExit

//Detroit7123

//ArrivalsinformationfromSecurityExit

//Detroit7123

//Kalamazoo7123

//ArrivalsinformationfromSecurityExit

//Detroit7123

//Kalamazoo7123

//NewYork-Kennedy4001

//ArrivalsinformationfromBaggageClaimMonitor1

//Detroit7123

//Kalamazoo7123

//NewYork-Kennedy4001

//SanFrancisco5112

//ArrivalsinformationfromSecurityExit

//Detroit7123

//Kalamazoo7123

//NewYork-Kennedy4001

//SanFrancisco5112

//ArrivalsinformationfromBaggageClaimMonitor1

//NewYork-Kennedy4001

//SanFrancisco5112

//ArrivalsinformationfromSecurityExit

//NewYork-Kennedy4001

//SanFrancisco5112

//ArrivalsinformationfromBaggageClaimMonitor1

//SanFrancisco5112

usingSystem;

usingSystem.Collections.Generic;

publicclassArrivalsMonitor:IObserverBaggageInfo

privatestringname;

privateListstringflightInfos=newListstring

privateIDisposablecancellation;

privatestringfmt="{0,-20}{1,5}{2,3}";

publicArrivalsMonitor(stringname)

if(String.IsNullOrEmpty(name))

thrownewArgumentNullException("Theobservermustbeassignedaname.");

=name;

publicvirtualvoidSubscribe(BaggageHandlerprovider)

//參數是處理者！添加觀察者this

cancellation=provider.Subscribe(this);

publicvirtualvoidUnsubscribe()

cancellation.Dispose();

flightInfos.Clear();

publicvirtualvoidOnCompleted()

flightInfos.Clear();

//Noimplementationneeded:MethodisnotcalledbytheBaggageHandlerclass.

publicvirtualvoidOnError(Exceptione)

//Noimplementation.

//Updateinformation.

publicvirtualvoidOnNext(BaggageInfoinfo)

boolupdated=false;

//Flighthasunloadeditsbaggage;removefromthemonitor.

if(info.Carousel==0)

varflightsToRemove=newListstring

stringflightNo=String.Format("{0,5}",info.FlightNumber);

foreach(varflightInfoinflightInfos)

if(flightInfo.Substring(21,5).Equals(flightNo))

flightsToRemove.Add(flightInfo);

updated=true;

foreach(varflightToRemoveinflightsToRemove)

flightInfos.Remove(flightToRemove);

flightsToRemove.Clear();

else

//Addflightifitdoesnotexistinthecollection.

stringflightInfo=String.Format(fmt,info.From,info.FlightNumber,info.Carousel);

if(!flightInfos.Contains(flightInfo))

flightInfos.Add(flightInfo);

updated=true;

if(updated)

flightInfos.Sort();

Console.WriteLine("Arrivalsinformationfrom{0}",);

foreach(varflightInfoinflightInfos)

Console.WriteLine(flightInfo);

Console.WriteLine();

usingSystem;

usingSystem.Collections.Generic;

publicclassBaggageHandler:IObservableBaggageInfo

privateListIObserverBaggageInfoobservers;

privateListBaggageInfoflights;

publicBaggageHandler()

observers=newListIObserverBaggageInfo();

flights=newListBaggageInfo

publicIDisposableSubscribe(IObserverBaggageInfoobserver)

//Checkwhetherobserverisalreadyregistered.Ifnot,addit

if(!observers.Contains(observer))

observers.Add(observer);

//Provideobserverwithexistingdata.

foreach(variteminflights)

observer.OnNext(item);

returnnewUnsubscriberBaggageInfo(observers,observer);

//Calledtoindicateallbaggageisnowunloaded.

publicvoidBaggageStatus(intflightNo)

BaggageStatus(flightNo,String.Empty,0);

publicvoidBaggageStatus(intflightNo,stringfrom,intcarousel)

varinfo=newBaggageInfo(flightNo,from,carousel);

//Carouselisassigned,soaddnewinfoobjecttolist.

if(carousel0!flights.Contains(info))

flights.Add(info);

foreach(varobserverinobservers)

observer.OnNext(info);

elseif(carousel==0)

//Baggageclaimforflightisdone

varflightsToRemove=newListBaggageInfo

foreach(varflightinflights)

if(info.FlightNumber==flight.FlightNumber)

flightsToRemove.Add(flight);

foreach(varobserverinobservers)

observer.OnNext(info);

foreach(varflightToRemoveinflightsToRemove)

flights.Remove(flightToRemove);

flightsToRemove.Clear();

publicvoidLastBaggageClaimed()

foreach(varobserverinobservers)

observer.OnCompleted();

observers.Clear();

usingSystem;

usingSystem.Collections.Generic;

publicclassBaggageInfo

privateintflightNo;

privatestringorigin;

privateintlocation;

internalBaggageInfo(intflight,stringfrom,intcarousel)

this.flightNo=flight;

this.origin=from;

this.location=carousel;

publicintFlightNumber

get{returnthis.flightNo;}

publicstringFrom

get{returnthis.origin;}

publicintCarousel

get{returnthis.location;}

usingSystem;

usingSystem.Colle