《中介者模式》PPT课件

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,*,*,第十二章 中介者模式,10/16/2024,1,中介者模式,用一个中介对象来封装一系列的对象交互。中介者使各对象不需要显示地相互引用，从而使其耦合松散，而且可以独立地改变它们之间的交互。,Mediator Pattern,Define an object that encapsulates how a set of objects interact.Mediator promotes loose coupling by keeping objects from referring to each other explicitly,and it lets you vary their interaction independently.,一、,概述,10/16/2024,3,中介者模式是封装一系列的对象交互的成熟模式，其关键是将对象之间的交互封装在称作中介者的对象中，中介者使各对象不需要显示地相互引用，这些对象只包含中介者的引用。当系统中某个对象需要和系统中另外一个对象交互时，只需将自己的请求通知中介者即可。,二、,中介者模式的结构与使用,10/16/2024,4,模式的结构中包括四种角色：,中介者（,Mediator,）,具体中介者（,ConcreteMediator,）,同事（,Colleague,）,具体同事（,ConcreteColleague,）,10/16/2024,5,模式的,UML,类图,模式的结构的描述与使用,古代相互交战的,A,B,C,三方，想通过一个中介者调停之间的战火。,A,方委托调停者转达的信息是：“要求,B,方归还曾抢夺的,100,斤土豆，要求,C,方归还曾抢夺的,20,头牛”；,B,方委托调停者转达的信息是：“要求,A,方归还曾抢夺的,10,只鸡，要求,C,方归还曾抢夺的,15,匹马”；,C,方委托调停者转达的信息是：“要求,A,方归还曾抢夺的,300,斤小麦，要求,B,方归还曾抢夺的,50,头驴”。,10/16/2024,8,1,同事（,Colleague,）,:,Colleague.java,public interface Colleague,public void,giveMess(String,mess);,public void,receiverMess(String,mess);,public void,setName(String,name);,public String,getName,();,注：本问题中，只需要一个具体中介者，我们并不需要一个中介者（,Mediator,）,接口。,10/16/2024,9,2,具体中介者,（,Mediator,）,:,ConcreteMediator.java,public class,ConcreteMediator,ColleagueA,colleagueA,;,ColleagueB,colleagueB,;,ColleagueC,colleagueC,;,public void,registerColleagueA(ColleagueA,colleagueA,),this.colleagueA,=,colleagueA,;,public void,registerColleagueB(ColleagueB,colleagueB,),this.colleagueB,=,colleagueB,;,public void,registerColleagueC(ColleagueC,colleagueC,),this.colleagueC,=,colleagueC,;,public void,deliverMess(Colleague,colleague,String,mess),if(colleague,=,colleagueA,),if(mess.length,=2),colleagueB.receiverMess(colleague.getName()+mess0);,colleagueC.receiverMess(colleague.getName()+mess1);,else,if(colleague,=,colleagueB,),if(mess.length,=2),colleagueA.receiverMess(colleague.getName()+mess0);,colleagueC.receiverMess(colleague.getName()+mess1);,else,if(colleague,=,colleagueC,),if(mess.length,=2),colleagueA.receiverMess(colleague.getName()+mess0);,colleagueB.receiverMess(colleague.getName()+mess1);,10/16/2024,11,3,具体同事（,ConcreteColleague,）,_1:,ColleagueA.java,public class,ColleagueA,implements Colleague,ConcreteMediator,mediator;String name;,ColleagueA(ConcreteMediator,mediator),this.mediator=mediator;,mediator.registerColleagueA(this,);,public void,setName(String,name),this.name=name;,public String,getName,(),return name;,public void,giveMess(String,mess),mediator.deliverMess(this,mess,);,public void,receiverMess(String,mess),System.out.println(name,+,收到的信息,:);,System.out.println(t+mess,);,10/16/2024,12,3,具体同事（,ConcreteColleague,）,_2:,ColleagueB.java,public class,ColleagueB,implements Colleague,ConcreteMediator,mediator;,String name;,ColleagueB(ConcreteMediator,mediator),this.mediator=mediator;,mediator.registerColleagueB(this,);,public void,setName(String,name),this.name=name;,public String,getName,(),return name;,public void,giveMess(String,mess),mediator.deliverMess(this,mess,);,public void,receiverMess(String,mess),System.out.println(name,+,收到的信息,:);,System.out.println(t+mess,);,10/16/2024,13,3,具体同事（,ConcreteColleague,）,_3:,ColleagueC.java,public class,ColleagueC,implements Colleague,ConcreteMediator,mediator;,String name;,ColleagueC(ConcreteMediator,mediator),this.mediator=mediator;,mediator.registerColleagueC(this,);,public void,setName(String,name),this.name=name;,public String,getName,(),return name;,public void,giveMess(String,mess),mediator.deliverMess(this,mess,);,public void,receiverMess(String,mess),System.out.println(name,+,收到的信息,:);,System.out.println(t+mess,);,10/16/2024,14,4,应用,Application.java,public class Application,public static void main(String,args,),ConcreteMediator,mediator=new,ConcreteMediator,();,ColleagueA,colleagueA,=new,ColleagueA(mediator,);,ColleagueB,colleagueB,=new,ColleagueB(mediator,);,ColleagueC,colleagueC,=new,ColleagueC(mediator,);,colleagueA.setName(A,国,);,colleagueB.setName(B,国,);,colleagueC.setName(C,国,);,String,messA,=,要求归还曾抢夺的,100,斤土豆,要求归还曾抢夺的,20,头牛,;,colleagueA.giveMess(messA,);,String,messB,=,要求归还曾抢夺的,10,只公鸡,要求归还曾抢夺的,15,匹马,;,colleagueB.giveMess(messB,);,String,messC,=,要求归还曾抢夺的,300,斤小麦,要求归还曾抢夺的,50,头驴,;,colleagueC.giveMess(messC,);,三、,中介者模式的优点,10/16/2024,15,可以避免许多的对象为了之间的通信而相互显示引用，不仅系统难于维护，而且也使其他系统难以复用这些对象。,可以通过中介者将原本分布于多个对象之间的交互行为集中在一起。当这些对象之间需要改变之间的通信行为时，只需使用一个具体中介者即可，不必修改各个具体同事的代码，即这些同事可被重用。,具体中介者使得各个具体同事完全解耦，修改任何一个具体同事的代码不会影响到其他同事。,具体中介者集中了同事之间是如何交互的细节，使得系统比较清楚地知道整个系统中的同事是如何交互的。,当一些对象想互相通信，但又无法相互包含对方的引用，那么使用中介者模式就可以使得这些对象互相通信。,四、适合使用中介者模式的情景,许多对象以复杂的方式交互，所导致的依赖关系使系统难以理解和维护。,一个对象引用其他很多对象，导致难以复用该对象。,