代表模式（Mediator Pattern）是一種行為型設計模式，它通過封裝一組對象之間的交互方式，使得這些對象之間的通信變得松散耦合，從而降低了對象之間的直接依賴關系。代表模式通過引入一個中介者（Mediator）對象，將對象之間的通信集中處理，從而減少了對象之間的相互依賴，使得系統(tǒng)更加靈活和可擴展。

在代表模式中，中介者對象充當了對象之間的調度者和協(xié)調者的角色，它封裝了對象之間的通信邏輯，負責接收和發(fā)送消息，并將消息傳遞給相關的對象。對象之間不再直接相互引用，而是通過中介者對象進行通信，從而達到松散耦合的效果。

以下是一個示例，展示了代表模式的應用場景和代碼實現(xiàn)：

// 中介者接口
interface Mediator {void sendMessage(String message, Colleague colleague);
}// 具體中介者
class ConcreteMediator implements Mediator {private Colleague colleague1;private Colleague colleague2;public void setColleague1(Colleague colleague1) {this.colleague1 = colleague1;}public void setColleague2(Colleague colleague2) {this.colleague2 = colleague2;}@Overridepublic void sendMessage(String message, Colleague colleague) {if (colleague == colleague1) {colleague2.receiveMessage(message);} else if (colleague == colleague2) {colleague1.receiveMessage(message);}}
}// 抽象同事類
abstract class Colleague {protected Mediator mediator;public Colleague(Mediator mediator) {this.mediator = mediator;}public abstract void send(String message);public abstract void receiveMessage(String message);
}// 具體同事類
class ConcreteColleague1 extends Colleague {public ConcreteColleague1(Mediator mediator) {super(mediator);}@Overridepublic void send(String message) {mediator.sendMessage(message, this);}@Overridepublic void receiveMessage(String message) {System.out.println("ConcreteColleague1 received message: " + message);}
}// 具體同事類
class ConcreteColleague2 extends Colleague {public ConcreteColleague2(Mediator mediator) {super(mediator);}@Overridepublic void send(String message) {mediator.sendMessage(message, this);}@Overridepublic void receiveMessage(String message) {System.out.println("ConcreteColleague2 received message: " + message);}
}// 測試代碼
public class MediatorPatternExample {public static void main(String[] args) {ConcreteMediator mediator = new ConcreteMediator();ConcreteColleague1 colleague1 = new ConcreteColleague1(mediator);ConcreteColleague2 colleague2 = new ConcreteColleague2(mediator);mediator.setColleague1(colleague1);mediator.setColleague2(colleague2);colleague1.send("Hello from colleague1!");colleague2.send("Hi from colleague2!");}
}

在上面的示例中，Mediator 接口定義了中介者的操作，ConcreteMediator 是具體的中介者實現(xiàn)。Colleague 是抽象同事類，ConcreteColleague1 和 ConcreteColleague2 是具體的同事類實現(xiàn)。

在 MediatorPatternExample 類中，我們創(chuàng)建了一個中介者對象 ConcreteMediator，并創(chuàng)建了兩個同事對象 ConcreteColleague1 和 ConcreteColleague2。然后，通過調用 setColleague1 和 setColleague2 方法將同事對象注冊到中介者中。

最后，我們通過調用同事對象的 send 方法發(fā)送消息，消息會經(jīng)過中介者進行轉發(fā)，最終到達目標同事對象，從而實現(xiàn)了對象之間的通信。

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