currentIndex++;
}
}
publicbooleanisDone（）{
return（currentIndex==objs.length）;
}
publicObjectcurrentItem（）{
returnobjs[currentIndex];
}
}
}
packagecom.javapatterns.iterator.blackbox;
publicinterfaceIterator{
voidfirst（）;
voidnext（）;
booleanisDone（）;
ObjectcurrentItem（）;
}
packagecom.javapatterns.iterator.blackbox;
publicclassClient{
/**
*@directed
*/
privateIteratorit;
/**
*@directed
*/
privateAggregateagg=newConcreteAggregate（）;
publicvoidoperation（）{
it=agg.createIterator（）;
while（!
it.isDone（））{
System.out.println（it.currentItem（）.toString（））;
it.next（）;
}
}
publicstaticvoidmain（String[]args）{
Clientclient=newClient（）;
client.operation（）;
}
}
（3）其它示例类图
十七、责任链（ChainofResponsibility）模式
（1）示例类图
（2）示例代码清单
packagecom.javapatterns.chainofresp.flowerpassingthread;
abstractclassPlayer{
abstractpublicvoidhandle（）;
/**
*@linkaggregation
*/
privatePlayersuccessor;
publicPlayer（）{
successor=null;
}
protectedvoidsetSuccessor（PlayeraSuccessor）{
successor=aSuccessor;
}
publicvoidnext（）{
if（successor!
=null）{
successor.handle（）;
}else{
System.out.println（"Programterminated."）;
}
}
}
packagecom.javapatterns.chainofresp.flowerpassingthread;
classJiaBaoYuextendsPlayer{
publicJiaBaoYu（PlayeraSuccessor）{
this.setSuccessor（aSuccessor）;
}
publicvoidhandle（）{
if（DrumBeater.stopped）{
System.out.println（"JiaBaoYugottadrink!
"）;
}else{
System.out.println（"JiaBaoYupassed!
"）;
next（）;
}
}
}
packagecom.javapatterns.chainofresp.flowerpassingthread;
classJiaHuanextendsPlayer{
publicJiaHuan（PlayeraSuccessor）{
this.setSuccessor（aSuccessor）;
}
publicvoidhandle（）{
if（DrumBeater.stopped）{
System.out.println（"JiaHuangottadrink!
"）;
}else{
System.out.println（"JiaHuanpassed!
"）;
next（）;
}
}
}
packagecom.javapatterns.chainofresp.flowerpassingthread;
classJiaMuextendsPlayer{
publicJiaMu（PlayeraSuccessor）{
this.setSuccessor（aSuccessor）;
}
publicvoidhandle（）{
if（DrumBeater.stopped）{
System.out.println（"JiaMugottadrink!
"）;
}else{
System.out.println（"JiaMupassed!
"）;
next（）;
}
}
}
packagecom.javapatterns.chainofresp.flowerpassingthread;
classJiaSheextendsPlayer{
publicJiaShe（PlayeraSuccessor）{
this.setSuccessor（aSuccessor）;
}
publicvoidhandle（）{
if（DrumBeater.stopped）{
System.out.println（"JiaShegottadrink!
"）;
}else{
System.out.println（"JiaShepassed!
"）;
next（）;
}
}
}
packagecom.javapatterns.chainofresp.flowerpassingthread;
classJiaZhengextendsPlayer{
publicJiaZheng（PlayeraSuccessor）{
this.setSuccessor（aSuccessor）;
}
publicvoidhandle（）{
if（DrumBeater.stopped）{
System.out.println（"JiaZhenggottadrink!
"）;
}else{
System.out.println（"JiaZhengpassed!
"）;
next（）;
}
}
}
packagecom.javapatterns.chainofresp.flowerpassingthread;
importjava.util.Timer;
importjava.util.TimerTask;
publicclassDrumBeater{
privatestaticPlayerfirstPlayer;
publicstaticbooleanstopped=false;
Timertimer;
staticpublicvoidmain（String[]args）{
DrumBeaterdrumBeater=newDrumBeater（）;
JiaMujiaMu=newJiaMu（null）;
jiaMu.setSuccessor（newJiaShe（newJiaZheng（newJiaBaoYu（newJiaHuan（
jiaMu）））））;
drumBeater.startBeating
（1）;
firstPlayer=jiaMu;
firstPlayer.handle（）;
}
publicvoidstartBeating（intstopInSeconds）{
System.out.println（"Drumbeatingstarted..."）;
timer=newTimer（）;
timer.schedule（newStopBeatingReminder（）,stopInSeconds*1000）;
}
classStopBeatingReminderextendsTimerTask{
publicvoidrun（）{
System.out.println（"Drumbeatingstopped!
"）;
stopped=true;
timer.cancel（）;//Terminatethetimerthread
}
}
}
十八、命令（Command）模式
（1）示例类图
（2）示例代码清单
packagemand;
publicinterfaceCommand{
voidexecute（）;
}
packagemand;
publicclassConcreteCommandimplementsCommand{
publicConcreteCommand（Receiverreceiver）{
this.receiver=receiver;
}
publicvoidexecute（）{
receiver.action（）;
}
/**
*@directed
*@clientRolereceiver
*/
privateReceiverreceiver;
}
packagemand;
publicclassInvoker{
publicInvoker（Commandcommand）{
mand=command;
}
publicvoidaction（）{
command.execute（）;
}
/**
*@linkaggregation
*@directed
*/
privateCommandcommand;
}
packagemand;
publicclassReceiver{
publicReceiver（）{
//writecodehere
}
publicvoidaction（）{
System.out.println（"Actionhasbeentaken."）;
}
}
packagemand;
publicclassClient{
publicstaticvoidmain（String[]args）{
Receiverreceiver=newReceiver（）;
Commandcommand=newConcreteCommand（receiver）;
Invokerinvoker=newInvoker（command）;
invoker.action（）;
}
}
（3）其它示例类图
十九、备忘录（Memento）模式：
又称快照（Snapshot）模式或Token模式
1、“白箱”备忘录模式
（1）示例类图
（2）示例代码清单
packagecom.javapatterns.memento.whitebox;
publicclassMemento{
privateStringstate;
publicMemento（Stringstate）{
this.state=state;
}
publicStringgetState（）{
returnthis.state;
}
publicvoidsetState（Stringstate）{
this.state=state;
}
}
packagecom.javapatterns.memento.whitebox;
publicclassOriginator{
privateStringstate;
/**
*@linkdependency
*@labelwide
*/
/*#MementolnkMemento;*/
publicMementocreateMemento（）{
returnnewMemento（state）;
}
publicvoidrestoreMemento（Mementomemento）{
this.state=memento.getState（）;
}
publicStringgetState（）{
returnthis.state;
}
publicvoidsetState（Stringstate）{
this.state=state;
System.out.println（"Currentstate="+this.state）;
}
}
packagecom.javapatterns.memento.whitebox;
publicclassCaretaker{
/**
*@linkaggregation
*@labelwide
*/
privateMementomemento;
publicMementoretrieveMemento（）{
returnthis.memento;
}
publicvoidsaveMemento（Mementomemento）{
this.memento=memento;
}
}
packagecom.javapatterns.memento.whitebox;
publicclassClient{
privatestaticOriginatoro=newOriginator（）;
privatestaticCaretakerc=newCaretaker（）;
publicstaticvoidmain（String[]args）{
o.setState（"On"）;
//Storeinternalstate
c.saveMemento（o.createMemento（））;
//Continuechangingoriginator
o.setState（"Off"）;
//Restoresavedstate
o.restoreMemento（c.retrieveMemento（））;
}
}
2、“白箱”备忘录模式
（1）示例类图
（2）示例代码清单
packagecom.javapatterns.memento.blackbox;
publicinterfaceMementoIF{
}
packagecom.javapatterns.memento.blackbox;
classMementoimplementsMementoIF{
privateStringsavedState;
/**
*@directed
*@labelIs-a-member-of
*/
privateOriginatorlnkOriginator;
privateMemento（StringsomeState）{
savedState=someState;
}
privatevoidsetState（StringsomeState）{
savedState=someState;
}
privateStringgetState（）{
returnsavedState;
}
}
packagecom.javapatterns.memento.blackbox;
publicclassOriginator{
publicOriginator（）{
}
privateStringstate;
/**
*@linkdependency
*@labelwide
*/
/*#MementoIFlnkMementoIF;*/
publicMementoIFcreateMemento
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