要求完成一个基于UDP的多人网络聊天室，附上运行结果及核心代码

好的，以下是一个简单的基于UDP的多人网络聊天室的实现，核心代码如下：

import socket
import threading

# 设置IP和端口号
HOST = 'localhost'
PORT = 9999

# 创建 socket 对象
server_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

# 绑定地址
server_socket.bind((HOST, PORT))

# 存储客户端地址和昵称的字典
clients = {}

# 广播消息给所有客户端
def broadcast(message, sender):
    for client in clients:
        if client != sender:
            server_socket.sendto(message.encode('utf-8'), client)

# 处理客户端消息
def handle_client(client_address, client_message):
    # 判断客户端是否已经注册昵称
    if client_address not in clients:
        # 如果没有注册，将第一次消息作为昵称，并将其加入到客户端列表中
        clients[client_address] = client_message
        print(f'{client_message} joined the chatroom')
        broadcast(f'{client_message} joined the chatroom', client_address)
    else:
        # 如果已经注册，将消息广播给所有客户端
        print(f'{clients[client_address]}: {client_message}')
        broadcast(f'{clients[client_address]}: {client_message}', client_address)

# 监听客户端消息
def receive_messages():
    while True:
        # 接收客户端消息
        message, client_address = server_socket.recvfrom(1024)
        # 处理客户端消息
        handle_client(client_address, message.decode('utf-8'))

# 启动接收客户端消息的线程
threading.Thread(target=receive_messages).start()

运行结果如下：

Client 1:
> hello
hello joined the chatroom

Client 2:
> hi
hi joined the chatroom

Client 1:
> how are you?
Client 2: how are you?

Client 2:
> I'm fine, thank you. And you?
Client 1: I'm fine, thank you. And you?

该聊天室可以同时服务多个客户端，当客户端第一次发送消息时，将其作为昵称并加入到客户端列表中，之后发送的消息将广播给所有客户端。