軟件體系結(jié)構(gòu)與設(shè)計模式第9章責(zé)任鏈模式

第九章責(zé)任鏈模式1責(zé)任鏈模式使多個對象都有時機(jī)處理請求，從而防止請求的發(fā)送者和接收者之間的耦合關(guān)系。將這些對象連成一條鏈，并沿著這條鏈傳遞該請求，直到有一個對象處理它為止。ChainofResponsibilityPatternAvoidcouplingthesenderofarequesttoitsreceiverbygivingmorethanoneobjectachancetohandletherequest.Chainthereceivingobjectsandpasstherequestalongthechainuntilanobjecthandlesit.1精選ppt2精選pptChainofResponsibility模式在軍隊中也有應(yīng)用的例子。某個下級軍官要求得到上級軍官的許可，這個請求將由其直接上級軍官再報給上級軍官的上級軍官，直到某個上級軍官有權(quán)利做決定為止。如果一名水兵請求進(jìn)入某個海軍基地，他說執(zhí)行的請求過程就是ChainofResponsibility的實例。3精選ppt一、概述4

責(zé)任鏈模式是使用多個對象處理用戶請求的成熟模式，責(zé)任鏈模式的關(guān)鍵是將用戶的請求分派給許多對象，這些對象被組織成一個責(zé)任鏈，即每個對象含有后繼對象的引用，并要求責(zé)任鏈上的每個對象，如果能處理用戶的請求，就做出處理，不再將用戶的請求傳遞給責(zé)任鏈上的下一個對象；如果不能處理用戶的請求，就必須將用戶的請求傳遞給責(zé)任鏈上的下一個對象。4精選ppt二、責(zé)任鏈模式的結(jié)構(gòu)與使用

5模式的結(jié)構(gòu)中包括兩種角色：處理者〔Handler〕具體處理者〔ConcreteHandler〕5精選ppt6模式的UML類圖

6精選pptaClientaHandleraConcreteHandlersuccessoraConcreteHandlersuccessor7精選ppt模式的結(jié)構(gòu)的描述與使用用戶提交一個人的身份證號碼，想知道該人是否在北京、上?；蛱旖蚓幼　?精選ppt91．處理者〔Handler〕:Handler.javapublicinterfaceHandler{publicabstractvoidhandleRequest(Stringnumber);publicabstractvoidsetNextHandler(Handlerhandler);}9精選ppt102．具體處理者〔ConcreteHandler〕_1:Beijing.javapublicclassBeijingimplementsHandler{privateHandlerhandler;privateArrayList<String>numberList;Beijing(){numberList=newArrayList<String>();numberList.add("11129812340930034");numberList.add("10120810340930632");numberList.add("22029812340930034");numberList.add("32620810340930632");}publicvoidhandleRequest(Stringnumber){if(numberList.contains(number))System.out.println("該人在北京居住");else{System.out.println("該人不在北京居住");if(handler!=null)handler.handleRequest(number);}}publicvoidsetNextHandler(Handlerhandler){this.handler=handler;}}10精選ppt112．具體處理者〔ConcreteHandler〕_2:Shanghai.javapublicclassShanghaiimplementsHandler{privateHandlerhandler;privateArrayList<String>numberList;Shanghai(){numberList=newArrayList<String>();numberList.add("34529812340930034");numberList.add("98720810340430632");numberList.add("36529812340930034");numberList.add("77720810340930632");}publicvoidhandleRequest(Stringnumber){if(numberList.contains(number))System.out.println("該人在上海居住");else{System.out.println("該人不在上海居住");if(handler!=null)handler.handleRequest(number);}}publicvoidsetNextHandler(Handlerhandler){this.handler=handler;}}11精選ppt122．具體處理者〔ConcreteHandler〕_3:Tianjin.javapublicclassTianjinimplementsHandler{privateHandlerhandler;privateArrayList<String>numberList;Tianjin(){numberList=newArrayList<String>();numberList.add("10029812340930034");numberList.add("20020810340430632");numberList.add("30029812340930034");numberList.add("50020810340930632");}publicvoidhandleRequest(Stringnumber){if(numberList.contains(number))System.out.println("該人在天津居住");else{System.out.println("該人不在天津居住");if(handler!=null)handler.handleRequest(number);}}publicvoidsetNextHandler(Handlerhandler){this.handler=handler;}}12精選ppt133．應(yīng)用Application.javapublicclassApplication{privateHandlerbeijing,shanghai,tianjin;publicvoidcreateChain(){beijing=newBeijing();shanghai=newShanghai();tianjin=newTianjin();beijing.setNextHandler(shanghai);shanghai.setNextHandler(tianjin);}publicvoidreponseClient(Stringnumber){beijing.handleRequest(number);}publicstaticvoidmain(Stringargs[]){Applicationapplication=newApplication();application.createChain();application.reponseClient("77720810340930632");;}}13精選ppt三、責(zé)任鏈模式的優(yōu)點14責(zé)任鏈中的對象只和自己的后繼是低耦合關(guān)系，和其他對象毫無關(guān)聯(lián)，這使得編寫處理者對象以及創(chuàng)立責(zé)任鏈變得非常容易。當(dāng)在處理者中分配職責(zé)時，責(zé)任鏈給應(yīng)用程序更多的靈活性。應(yīng)用程序可以動態(tài)地增加、刪除處理者或重新指派處理者的職責(zé)。應(yīng)用程序可以動態(tài)地改變處理者之間的先后順序。使用責(zé)任鏈的用戶不必知道處理者的信息，用戶不會知道到底是哪個對象處理了它的請求。14精選ppt四、應(yīng)用舉例//Handler.javapublicinterfaceHandler{publicabstractvoidcompuerMultiply(Stringnumber);publicabstractvoidsetNextHandler(Handlerhandler);}15精選pptpublicclassUseIntimplementsHandler{privateHandlerhandler;privateintresult=1;publicvoidcompuerMultiply(Stringnumber){try{intn=Integer.parseInt(number);inti=1;while(i<=n){result=result*i;if(result<=0){System.out.println(“超出我的能力范圍，我計算不了");handlerpuerMultiply(number);return;}i++;}System.out.println(number+“的階乘:"+result);}catch(NumberFormatExceptionexp){System.out.println(exp.toString());}}publicvoidsetNextHandler(Handlerhandler){this.handler=handler;}}16精選pptpublicclassUseLongimplementsHandler{privateHandlerhandler;privatelongresult=1;publicvoidcompuerMultiply(Stringnumber){try{longn=Long.parseLong(number);longi=1;while(i<=n){result=result*i;if(result<=0){System.out.println(“超出我的能力范圍，我計算不了");handlerpuerMultiply(number);return;}i++;}System.out.println(number+“的階乘:"+result);}catch(NumberFormatExceptionexp){System.out.println(exp.toString());}}publicvoidsetNextHandler(Handlerhandler){this.handler=handler;}}17精選pptimportjava.math.BigInteger;publicclassUseBigIntegerimplementsHandler{privateHandlerhandler;privateBigIntegerresult=newBigInteger("1");publicvoidcompuerMultiply(Stringnumber){try{BigIntegern=newBigInteger(number);BigIntegerONE=newBigInteger("1");BigIntegeri=ONE;while(ipareTo(n)<=0){result=result.multiply(i);i=i.add(ONE);}System.out.println(number+"??????:"+result);}catch(NumberFormatEx