软件设计： 实验19：中介者模式

实验19：中介者模式

本次实验属于模仿型实验，通过本次实验学生将掌握以下内容： 

1、理解中介者模式的动机，掌握该模式的结构；

2、能够利用中介者模式解决实际问题。

 

[实验任务一]：虚拟聊天室

在“虚拟聊天室”实例中增加一个新的具体聊天室类和一个新的具体会员类，要求如下：

1. 新的具体聊天室中发送的图片大小不得超过20M。

2. 新的具体聊天室中发送的文字长度不得超过100个字符。

3. 新的具体会员类可以发送图片信息和文本信息。

4. 新的具体会员类在发送文本信息时，可以在信息后加上时间。

修改客户端测试类，注意原有系统类代码和客户端代码的修改。

实验要求：

1. 画出对应的类图；

2. 提交源代码；

3. 注意编程规范。

 

1.

 

2.

// 抽象中介者类

abstract class Mediator {

    public abstract void send(String message, Client client);

    public abstract void sendImage(String image, Client client);

}

 

// 具体中介者类

class ChatRoomMediator extends Mediator {

    private List<Client> clients = new ArrayList<>();

 

    public void addClient(Client client) {

        clients.add(client);

    }

 

    @Override

    public void send(String message, Client client) {

        for (Client c : clients) {

            if (c != client) {

                c.receive(message);

            }

        }

    }

 

    @Override

    public void sendImage(String image, Client client) {

        for (Client c : clients) {

            if (c != client) {

                c.receiveImage(image);

            }

        }

    }

}

 

// 抽象客户端类

abstract class Client {

    protected Mediator mediator;

    protected String name;

 

    public Client(Mediator mediator, String name) {

        this.mediator = mediator;

        this.name = name;

    }

 

    public abstract void sendMessage(String message);

    public abstract void sendImage(String image);

    public abstract void receive(String message);

    public abstract void receiveImage(String image);

}

 

// 具体客户端类

class ConcreteChatRoom extends Client {

    public ConcreteChatRoom(Mediator mediator, String name) {

        super(mediator, name);

    }

 

    @Override

    public void sendMessage(String message) {

        if (message.length() <= 100) {

            mediator.send(message, this);

        }

    }

 

    @Override

    public void sendImage(String image) {

        if (image.getBytes().length <= 20 * 1024 * 1024) {

            mediator.sendImage(image, this);

        }

    }

 

    @Override

    public void receive(String message) {

        System.out.println(name + " received message: " + message);

    }

 

    @Override

    public void receiveImage(String image) {

        System.out.println(name + " received image.");

    }

}

 

// 新的具体客户端类

class NewClient extends Client {

    public NewClient(Mediator mediator, String name) {

        super(mediator, name);

    }

 

    @Override

    public void sendMessage(String message) {

        if (message.length() <= 100) {

            mediator.send(message + " [" + new Date() + "]", this);

        }

    }

 

    @Override

    public void sendImage(String image) {

        if (image.getBytes().length <= 20 * 1024 * 1024) {

            mediator.sendImage(image, this);

        }

    }

 

    @Override

    public void receive(String message) {

        System.out.println(name + " received message: " + message);

    }

 

    @Override

    public void receiveImage(String image) {

        System.out.println(name + " received image.");

    }

}

 

// 客户端测试类

public class ChatRoomTest {

    public static void main(String[] args) {

        ChatRoomMediator mediator = new ChatRoomMediator();

        ConcreteChatRoom chatRoom1 = new ConcreteChatRoom(mediator, "ChatRoom1");

        ConcreteChatRoom chatRoom2 = new ConcreteChatRoom(mediator, "ChatRoom2");

        NewClient newClient = new NewClient(mediator, "NewClient");

 

        mediator.addClient(chatRoom1);

        mediator.addClient(chatRoom2);

        mediator.addClient(newClient);

 

        chatRoom1.sendMessage("Hello, World!");

        newClient.sendMessage("Hello, New World!");

        chatRoom1.sendImage("image1.jpg");

        newClient.sendImage("image2.jpg");

    }

}