用python写一个多人聊天室客户端和服务端的代码，要求能实现文件传输和实时查看在线人数

好的，以下是一个简单的多人聊天室客户端和服务端的Python代码，满足您的要求。其中使用了socket、select、threading等模块实现。

服务端代码：

import socket
import select
import threading

HOST = '127.0.0.1'
PORT = 8888
MAX_CLIENTS = 10

server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
server_socket.bind((HOST, PORT))
server_socket.listen(MAX_CLIENTS)

clients = []
clients_lock = threading.Lock()

def broadcast(message, sender):
    with clients_lock:
        for client in clients:
            if client != sender:
                try:
                    client.send(message)
                except:
                    clients.remove(client)

def handle_client(client_socket, addr):
    with clients_lock:
        clients.append(client_socket)
    while True:
        try:
            message = client_socket.recv(1024)
            if message:
                broadcast(message, client_socket)
            else:
                raise Exception('Client disconnected')
        except:
            with clients_lock:
                clients.remove(client_socket)
            client_socket.close()
            return

def count_online():
    while True:
        with clients_lock:
            online_num = len(clients)
            print('Online: {}'.format(online_num))
        for client in clients:
            try:
                client.send(('Online: {}\n'.format(online_num)).encode())
            except:
                clients.remove(client)
        threading.Event().wait(5)

count_thread = threading.Thread(target=count_online)
count_thread.daemon = True
count_thread.start()

while True:
    client_socket, addr = server_socket.accept()
    threading.Thread(target=handle_client, args=(client_socket, addr)).start()

客户端代码：

import socket
import select
import threading
import sys
import os

HOST = '127.0.0.1'
PORT = 8888

client_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
client_socket.connect((HOST, PORT))

def receive():
    while True:
        try:
            message = client_socket.recv(1024)
            if message:
                sys.stdout.write(message.decode())
                sys.stdout.flush()
            else:
                raise Exception('Server disconnected')
        except:
            client_socket.close()
            os._exit(0)

def send():
    while True:
        message = sys.stdin.readline()
        if message.strip() == '':
            continue
        client_socket.send(message.encode())

def file_send():
    while True:
        message = sys.stdin.readline().strip()
        if message == '':
            continue
        try:
            filename = message.split()[-1]
            with open(filename, 'rb') as f:
                client_socket.send('file {}'.format(os.path.basename(filename)).encode())
                client_socket.send(f.read())
        except:
            print('File not found')

receive_thread = threading.Thread(target=receive)
receive_thread.daemon = True
receive_thread.start()

send_thread = threading.Thread(target=send)
send_thread.daemon = True
send_thread.start()

file_thread = threading.Thread(target=file_send)
file_thread.daemon = True
file_thread.start()

while True:
    pass

客户端支持文件传输，发送文件时输入文件名即可，服务端会自动转发给所有客户端。同时客户端也支持实时查看在线人数，服务端会每隔5秒广播当前在线人数给所有客户端。