设计模式-中介者模式

中介者模式（Mediator Pattern）
用一个中介对象来封装一系列对象之间的交互，使各个对象不需要显式地引用其他对象实例，从而降低各个对象之间的耦合度，并且可以独立地改变对象间的交互关系。

举例：多人聊天，一个人发消息，其他人都能收到（服务器相当于中介者）

抽象用户类public abstract class AbstractUser{private IMediator mediator;private String name;public AbstractUser(String name,IMediator mediator){this.name=name;this.mediator=mediator;}public String getName() {return name;}public void receiveMessage(String msg){System.out.println(this.name+"收到消息："+msg);}public void sendMessage(String msg){System.out.println(this.name+"说："+msg);mediator.notifyAllUser(this,msg);}}

中介者接口

public interface IMediator {/** * description 注册用户 * @param user */public void register(AbstractUser user);/** * description 消息广播 * @param sendUser */public void notifyAllUser(AbstractUser sendUser,String msg);}

实际中介者类

public class Mediator implements IMediator{private ArrayList<AbstractUser> userList=new ArrayList<AbstractUser>();@Overridepublic void register(AbstractUser user) {if(user!=null&&!userList.contains(user)){userList.add(user);}}@Overridepublic void notifyAllUser(AbstractUser sendUser,String msg) {for(AbstractUser user:userList){if(!user.equals(sendUser)){user.receiveMessage(msg);}}}}

三个用户类

public class UserA extends AbstractUser{public UserA(String name, IMediator mediator) {super(name, mediator);mediator.register(this);}}public class UserB extends AbstractUser{public UserB(String name, IMediator mediator) {super(name, mediator);mediator.register(this);}}public class UserC extends AbstractUser{public UserC(String name, IMediator mediator) {super(name, mediator);mediator.register(this);}}

测试类

public class Demo {public static void main(String[] args) {IMediator mediator=new Mediator();UserA a=new UserA("a", mediator);UserB b=new UserB("b", mediator);UserC c=new UserC("c", mediator);a.sendMessage("大家好！");System.out.println("---------");b.sendMessage("大家辛苦了！");System.out.println("---------");c.sendMessage("为人民服务！");}}

测试结果

a说：大家好！b收到消息：大家好！c收到消息：大家好！---------b说：大家辛苦了！a收到消息：大家辛苦了！c收到消息：大家辛苦了！---------c说：为人民服务！a收到消息：为人民服务！b收到消息：为人民服务！