《Java与模式》重点总结05.docx
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《Java与模式》重点总结05
第三部分行为模式
十二、不变（Immutable）模式
（1）示例类图
（2）示例代码清单
packagecom.javapatterns.immutable.point;
importjava.io.Serializable;
publicclassPointimplementsSerializable{
privateintx;
privateinty;
publicPoint（intx,inty）{
this.x=x;
this.y=y;
}
publicPoint（）{
this（0,0）;
}
publicPoint（Pointp）{
this（p.x,p.y）;
}
/**
*ReturnstheXcoordinateofthepointindoubleprecision.
*/
publicdoublegetX（）{
returnx;
}
/**
*ReturnstheYcoordinateofthepointindoubleprecision.
*/
publicdoublegetY（）{
returny;
}
/**
*Returnsthelocationofthispoint.Thismethodisincludedfor
*completeness,toparallelthegetLocationmethodof
*Component.
*
*@returnacopyofthispoint,atthesamelocation.
*/
publicPointgetLocation（）{
returnnewPoint（x,y）;
}
/**
*Setsthelocationofthepointtothespecificedlocation.Thismethodis
*includedforcompleteness,toparallelthesetLocation
*methodofComponent.
*
*@paramp
*apoint,thenewlocationforthispoint.
*/
publicPointsetLocation（Pointp）{
returnnewPoint（p.x,p.y）;
}
/**
*Changesthepointtohavethespecificedlocation.
*
*Thismethodisincludedforcompleteness,toparallelthe
*setLocationmethodofComponent.Itsbehavior
*isidenticalwithmove（int, int）.
*
*@paramx
*thexcoordinateofthenewlocation.
*@paramy
*theycoordinateofthenewlocation.
*/
publicPointsetLocation（intx,inty）{
returnnewPoint（x,y）;
}
/**
*Setsthelocationofthispointtothespecifiedfloatcoordinates.
*/
publicPointsetLocation（doublex,doubley）{
returnnewPoint（（int）Math.round（x）,（int）Math.round（y））;
}
/**
*Movesthispointtothespecificedlocationinthe
*（x, y）coordinateplane.Thismethodisidenticalwith
*setLocation（int, int）.
*
*@paramx
*thexcoordinateofthenewlocation.
*@paramy
*theycoordinateofthenewlocation.
*/
publicPointmove（intx,inty）{
returnnewPoint（x,y）;
}
/**
*Translatesthispoint,atlocation（x, y）,by
*dxalongthexaxisanddyalongthe
*yaxissothatitnowrepresentsthepoint（x
*+ dx,y +
* dy）.
*
*@paramx
*thedistancetomovethispointalongthexaxis.
*@paramy
*thedistancetomovethispointalongtheyaxis.
*/
publicPointtranslate（intx,inty）{
returnnewPoint（this.x+x,this.y+y）;
}
/**
*DetermineswhetheraninstanceofPoint2Disequaltothis
*point.TwoinstancesofPoint2Dareequalifthevaluesof
*theirxandymemberfields,representingtheir
*positioninthecoordinatespace,arethesame.
*
*@paramobj
*anobjecttobecomparedwiththispoint.
*@returntrueiftheobjecttobecomparedisaninstanceof
*Point2Dandhasthesamevalues;false
*otherwise.
*/
publicbooleanequals（Objectobj）{
if（objinstanceofPoint）{
Pointpt=（Point）obj;
return（x==pt.x）&&（y==pt.y）;
}
returnsuper.equals（obj）;
}
/**
*Returnsastringrepresentationofthispointanditslocationinthe
*（x, y）coordinatespace.Thismethodisintendedtobe
*usedonlyfordebuggingpurposes,andthecontentandformatofthe
*returnedstringmayvarybetweenimplementations.Thereturnedstringmay
*beemptybutmaynotbenull.
*
*@returnastringrepresentationofthispoint.
*/
publicStringtoString（）{
returngetClass（）.getName（）+"[x="+x+",y="+y+"]";
}
}
十三、策略（Strategy）模式
（1）示例类图
（2）示例代码清单
packagecom.javapatterns.strategy.sortarray;
abstractpublicclassSortStrategy{
publicabstractvoidsort（）;
}
packagecom.javapatterns.strategy.sortarray;
publicclassBinSortextendsSortStrategy{
publicvoidsort（）{
//sortinglogichere
}
}
packagecom.javapatterns.strategy.sortarray;
publicclassBubbleSortextendsSortStrategy{
publicvoidsort（）{
//sortinglogichere
}
}
packagecom.javapatterns.strategy.sortarray;
publicclassHeapSortextendsSortStrategy{
publicvoidsort（）{
//sortinglogichere
}
}
packagecom.javapatterns.strategy.sortarray;
publicclassQuickSortextendsSortStrategy{
publicvoidsort（）{
//sortinglogichere
}
}
packagecom.javapatterns.strategy.sortarray;
publicclassRadixSortextendsSortStrategy{
publicvoidsort（）{
//sortinglogichere
}
}
packagecom.javapatterns.strategy.sortarray;
publicclassSorter{
/**
*@linkaggregation
*@directed
*/
privateSortStrategysortStrategy;
publicvoidsort（）{
sortStrategy.sort（）;
}
publicvoidsetSortStrategy（SortStrategysort）{
this.sortStrategy=sort;
}
}
（3）其它类图
十四、模版方法（TemplateMethod）模式
（1）示例类图
（2）示例代码清单
packagecom.javapatterns.templatemethod.InterestRate;
abstractpublicclassAccount{
protectedStringaccountNumber;
publicAccount（）{
accountNumber=null;
}
publicAccount（StringaccountNumber）{
this.accountNumber=accountNumber;
}
finalpublicdoublecalculateInterest（）{
doubleinterestRate=doCalculateInterestRate（）;
StringaccountType=doCalculateAccountType（）;
doubleamount=calculateAmount（accountType,accountNumber）;
returnamount*interestRate;
}
abstractprotectedStringdoCalculateAccountType（）;
abstractprotecteddoubledoCalculateInterestRate（）;
finalpublicdoublecalculateAmount（StringaccountType,StringaccountNumber）{
//retrieveamountfromdatabase...hereisonlyamock-up
return7243.00D;
}
}
packagecom.javapatterns.templatemethod.InterestRate;
publicclassMoneyMarketAccountextendsAccount{
publicStringdoCalculateAccountType（）{
return"MoneyMarket";
}
publicdoubledoCalculateInterestRate（）{
return0.045D;
}
}
packagecom.javapatterns.templatemethod.InterestRate;
publicclassCDAccountextendsAccount{
publicStringdoCalculateAccountType（）{
return"CertificateofDeposite";
}
publicdoubledoCalculateInterestRate（）{
return0.065D;
}
}
packagecom.javapatterns.templatemethod.InterestRate;
publicclassClient{
privatestaticAccountacct=null;
publicstaticvoidmain（String[]args）{
acct=newMoneyMarketAccount（）;
System.out.println（"InterestearnedfromMoneyMarketaccount="
+acct.calculateInterest（））;
acct=newCDAccount（）;
System.out.println（"InterestearnedfromCDaccount="
+acct.calculateInterest（））;
}
}
十五、观察者（Observer）模式
1、方案一
（1）示例类图
（2）示例代码清单
packagecom.javapatterns.observer;
publicinterfaceSubject{
publicvoidattach（Observerobserver）;
publicvoiddetach（Observerobserver）;
voidnotifyObservers（）;
}
packagecom.javapatterns.observer;
importjava.util.Vector;
importjava.util.Enumeration;
publicclassConcreteSubjectimplementsSubject{
/**
*@associates<{Observer}>
*@linkaggregation
*@supplierCardinality0..*
*/
privateVectorobserversVector=newVector（）;
publicvoidattach（Observerobserver）{
observersVector.addElement（observer）;
}
publicvoiddetach（Observerobserver）{
observersVector.removeElement（observer）;
}
publicvoidnotifyObservers（）{
Enumerationenumeration=observers（）;
while（enumeration.hasMoreElements（））{
（（Observer）enumeration.nextElement（））.update（）;
}
}
publicEnumerationobservers（）{
return（（Vector）observersVector.clone（））.elements（）;
}
}
packagecom.javapatterns.observer;
publicinterfaceObserver{
voidupdate（）;
}
packagecom.javapatterns.observer;
importjava.util.Observable;
importjava.util.Observer;
publicclassConcreteObserverimplementsObserver{
publicvoidupdate（Observableo,Objectarg）{
//Writeyourcodehere
}
}
2、方案二
（1）示例类图
（2）示例代码清单
packagecom.javapatterns.observer.variation;
importjava.util.Vector;
importjava.util.Enumeration;
abstractpublicclassSubject{
/**
*@associates<{Observer}>
*@linkaggregation
*@supplierCardinality0..*
*/
privateVectorobserversVector=newVector（）;
publicvoidattach（Observerobserver）{
observersVector.addElement（observer）;
System.out.println（"Attachedanobserver."）;
}
publicvoiddetach（Observerobserver）{
observersVector.removeElement（observer）;
}
publicvoidnotifyObservers（）{
Enumerationenumeration=observers（）;
while（enumeration.hasMoreElements（））{
System.out.println（"Beforenotifying"）;
（（Observer）enumeration.nextElement（））.update（）;
}
}
publicEnumerationobservers（）{
return（（Vector）observersVector.clone（））.elements（）;
}
}
packagecom.javapatterns.observer.variation;
publicclassConcreteSubjectextendsSubject{
privateStringstate;
publicvoidchange（StringnewState）{
state=newState;
this.notifyObservers（）;
}
}
packagecom.javapatterns.observer.variation;
publicinterfaceObserver{
voidupdate（）;
}
packagecom.javapatterns.observer.variation;
publicclassConcreteObserverimplementsObserver{
publicvoidupdate（）{
System.out.println（"Iamnotified"）;
}
}
packagecom.javapatterns.observer.variation;
publicclassClient{
privatestaticConcreteSubjectsubject;
privatestaticObserverobserver;
publicstaticvoidmain（String[]args）{
subject=newConcreteSubject（）;
observer=newConcreteObserver（）;
subject
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