10.23

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；

import datetime

class ChatRoomMediator:
    def __init__(self):
        self.members = []

    def add_member(self, member):
        self.members.append(member)
        member.set_mediator(self)

    def send_message(self, sender, message):
        for member in self.members:
            if member != sender:  # 只让其他成员接收消息
                member.receive_message(sender, message)

class Member:
    def __init__(self, name):
        self.name = name
        self.mediator = None

    def set_mediator(self, mediator):
        self.mediator = mediator

    def send_message(self, message):
        self.mediator.send_message(self, message)

    def receive_message(self, sender, message):
        raise NotImplementedError("This method should be overridden in subclasses.")

class LimitedChatRoom(Member):
    MAX_IMAGE_SIZE = 20 * 1024 * 1024  # 20MB
    MAX_TEXT_LENGTH = 100

    def __init__(self, name="Limited Chat Room"):
        super().__init__(name)

    def receive_message(self, sender, message):
        if isinstance(message, ImageMessage):
            if message.size > self.MAX_IMAGE_SIZE:
                print(f"图片大小超过限制：{message.size / (1024 * 1024):.2f}MB，来自 {sender.name}")
                return
            print(f"{sender.name} 发送了一张图片: {message.url} ({message.size / (1024 * 1024):.2f}MB)")
        elif isinstance(message, TextMessage):
            if len(message.content) > self.MAX_TEXT_LENGTH:
                print(f"文本长度超过限制，来自 {sender.name}。")
                return
            timestamp = datetime.datetime.now().strftime("%Y-%m-%d %H:%M:%S")
            print(f"{sender.name} 发送了文本: {message.content} [发送时间: {timestamp}]")
        else:
            print("不支持的消息类型。")

class ChatMember(Member):
    def send_image(self, url, size):
        image_message = ImageMessage(url, size)
        self.send_message(image_message)

    def send_text(self, content):
        text_message = TextMessage(content)
        self.send_message(text_message)

    def receive_message(self, sender, message):
        # 在此处处理接收到的消息
        if isinstance(message, ImageMessage):
            print(f"{self.name} 收到了一张图片，来自 {sender.name}: {message.url} ({message.size / (1024 * 1024):.2f}MB)")
        elif isinstance(message, TextMessage):
            print(f"{self.name} 收到了一条文本消息，来自 {sender.name}: {message.content}")

class Message:
    pass

class ImageMessage(Message):
    def __init__(self, url, size):
        self.url = url
        self.size = size

class TextMessage(Message):
    def __init__(self, content):
        self.content = content

    # 客户端测试类
def main():
    mediator = ChatRoomMediator()

    chat_room = LimitedChatRoom("Limited Chat Room")
    mediator.add_member(chat_room)

    member1 = ChatMember("Alice")
    member2 = ChatMember("Bob")

    mediator.add_member(member1)
    mediator.add_member(member2)

    # 测试发送图片
    member1.send_image("http://example.com/image1.jpg", 15 * 1024 * 1024)  # 15MB
    member2.send_image("http://example.com/image2.jpg", 25 * 1024 * 1024)  # 25MB，超过限制

    # 测试发送文本
    member1.send_text("Hello, this is a test message.")
    member2.send_text("This is a very long message that exceeds the limit of one hundred characters. "
                      "This part is just to ensure that the message length is indeed more than one hundred characters.")

if __name__ == "__main__":
    main()

 

3. 注意编程规范。