12.17

 

 

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；

package org.test19;

 

public interface ChatMediator {

    void sendMessage(Message message, Member member);

}

 

 

package org.test19;

 

public class Client {

    public static void main(String[] args) {

        ChatMediator chatMediator = new ConcreteChatMediator();

 

        Member member1 = new ConcreteMember("Alice", chatMediator);

        Member member2 = new ConcreteMember("Bob", chatMediator);

 

        member1.sendMessage(new TextMessage("Hello, how are you?"));

        member2.sendMessage(new ImageMessage(15 * 1024 * 1024));  // This should work

        member1.sendMessage(new TextMessage("I'm good, thanks! How about you?"));

        member2.sendMessage(new ImageMessage(25 * 1024 * 1024));

 

    }

}

 

 

 

 

package org.test19;

 

public class ConcreteChatMediator implements ChatMediator{

    @Override

    public void sendMessage(Message message, Member member) {

        // 处理消息的发送逻辑

        member.receiveMessage(message);

    }

}

 

 

 

 

package org.test19;

 

public class ConcreteMember implements Member{

    private String name;

    private ChatMediator chatMediator;

 

    ConcreteMember(String name, ChatMediator chatMediator) {

        this.name = name;

        this.chatMediator = chatMediator;

    }

 

    @Override

    public void sendMessage(Message message) {

        if (message != null) {

            // 在这里进行图片大小和文本长度的判断

            if (message instanceof TextMessage) {

                if (((TextMessage) message).getContent().length() > 100) {

                    System.out.println("Text message too long. Limit is 100 characters. Message not sent.");

                    return;

                }

            } else if (message instanceof ImageMessage) {

                if (((ImageMessage) message).getSizeInMegaBytes() > 20) {

                    System.out.println("Image size too large. Message not sent.");

                    return;

                }

            }

 

            chatMediator.sendMessage(message, this);

        } else {

            System.out.println("Message not sent.");

        }

    }

 

    @Override

    public void receiveMessage(Message message) {

        if (message != null) {

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

        } else {

            System.out.println(name + " did not receive the message.");

        }

    }

}

 

 

 

 

package org.test19;

 

public class ImageMessage extends Message{

    private int sizeInBytes;

 

    ImageMessage(int sizeInBytes) {

        this.sizeInBytes = sizeInBytes;

    }

 

    int getSizeInMegaBytes() {

        return sizeInBytes / (1024 * 1024);

    }

 

    @Override

    public String getContent() {

        return "Image Size: " + sizeInBytes + " bytes";

    }

}

 

 

 

 

package org.test19;

 

public interface Member {

    void sendMessage(Message message);

    void receiveMessage(Message message);

}

 

 

 

 

 

package org.test19;

 

public abstract class Message {

    public abstract  String getContent();

}

 

 

 

 

 

package org.test19;

 

public class TextMessage extends Message{

 

    private String content;

 

    TextMessage(String content) {

        this.content = content;

    }

 

    @Override

    public String getContent() {

        return content;

    }

}package org.test19;

 

public interface ChatMediator {

    void sendMessage(Message message, Member member);

}

 

 

package org.test19;

 

public class Client {

    public static void main(String[] args) {

        ChatMediator chatMediator = new ConcreteChatMediator();

 

        Member member1 = new ConcreteMember("Alice", chatMediator);

        Member member2 = new ConcreteMember("Bob", chatMediator);

 

        member1.sendMessage(new TextMessage("Hello, how are you?"));

        member2.sendMessage(new ImageMessage(15 * 1024 * 1024));  // This should work

        member1.sendMessage(new TextMessage("I'm good, thanks! How about you?"));

        member2.sendMessage(new ImageMessage(25 * 1024 * 1024));

 

    }

}

 

 

 

 

package org.test19;

 

public class ConcreteChatMediator implements ChatMediator{

    @Override

    public void sendMessage(Message message, Member member) {

        // 处理消息的发送逻辑

        member.receiveMessage(message);

    }

}

 

 

 

 

package org.test19;

 

public class ConcreteMember implements Member{

    private String name;

    private ChatMediator chatMediator;

 

    ConcreteMember(String name, ChatMediator chatMediator) {

        this.name = name;

        this.chatMediator = chatMediator;

    }

 

    @Override

    public void sendMessage(Message message) {

        if (message != null) {

            // 在这里进行图片大小和文本长度的判断

            if (message instanceof TextMessage) {

                if (((TextMessage) message).getContent().length() > 100) {

                    System.out.println("Text message too long. Limit is 100 characters. Message not sent.");

                    return;

                }

            } else if (message instanceof ImageMessage) {

                if (((ImageMessage) message).getSizeInMegaBytes() > 20) {

                    System.out.println("Image size too large. Message not sent.");

                    return;

                }

            }

 

            chatMediator.sendMessage(message, this);

        } else {

            System.out.println("Message not sent.");

        }

    }

 

    @Override

    public void receiveMessage(Message message) {

        if (message != null) {

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

        } else {

            System.out.println(name + " did not receive the message.");

        }

    }

}

 

 

 

 

package org.test19;

 

public class ImageMessage extends Message{

    private int sizeInBytes;

 

    ImageMessage(int sizeInBytes) {

        this.sizeInBytes = sizeInBytes;

    }

 

    int getSizeInMegaBytes() {

        return sizeInBytes / (1024 * 1024);

    }

 

    @Override

    public String getContent() {

        return "Image Size: " + sizeInBytes + " bytes";

    }

}

 

 

 

 

package org.test19;

 

public interface Member {

    void sendMessage(Message message);

    void receiveMessage(Message message);

}

 

 

 

 

 

package org.test19;

 

public abstract class Message {

    public abstract  String getContent();

}

 

 

 

 

 

package org.test19;

 

public class TextMessage extends Message{

 

    private String content;

 

    TextMessage(String content) {

        this.content = content;

    }

 

    @Override

    public String getContent() {

        return content;

    }

}

3. 注意编程规范。