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用Python轻松构建聊天应用：从零到成型

聊天应用程序是许多开发者入门的经典项目之一。通过合理利用多线程和网络编程，我们可以在短短几百行代码中完成一个功能齐全的聊天系统。以下将详细介绍如何从零开始，逐步搭建一个无依赖的聊天应用程序。

服务器端：多线程处理聊天

服务器端的主要功能包括接收客户端连接、处理消息广播以及管理客户端会话。我们使用标准的socket库和多线程技术来实现这一点。

from socket import AF_INET, socket, SOCK_STREAM
from threading import Thread

2. 初始化常量：

BUFSIZ = 1024  # 数据传输缓冲大小
ADDR = (HOST, PORT)  # 服务器地址和端口

3. 接收连接并处理消息：

def accept_incoming_connections():
    while True:
        client, client_address = SERVER.accept()
        print(f"{client_address} has connected.")
        client.send("欢迎来到聊天室！请输入你的名字并按回车。".encode("utf-8"))
        addresses[client] = client_address
        Thread(target=handle_client, args=(client,)).start()

4. 处理单个客户端连接：

def handle_client(client):
    name = client.recv(BUFSIZ).decode("utf-8")
    welcome = f"欢迎 {name}！输入 {quit} 退出。"
    client.send(welcome.encode("utf-8"))
    broadcast(f"{name} 已加入聊天。", name)
    clients[client] = name
    while True:
        msg = client.recv(BUFSIZ)
        if not msg:
            break
        if msg.decode("utf-8") == "{quit}":
            client.send("{quit}".encode("utf-8"))
            client.close()
            del clients[client]
            broadcast(f"{name} 已离开聊天。", name)
            break
        broadcast(f"{name}: {msg.decode('utf-8')}", name)

5. 广播消息：

def broadcast(msg, prefix=""):
    for sock in clients:
        sock.send(f"{prefix}{msg}".encode("utf-8"))

6. 启动服务器：

if __name__ == "__main__":
    SERVER.listen(5)
    print("正在侦听连接...")
    accept_thread = Thread(target=accept_incoming_connections)
    accept_thread.start()
    accept_thread.join()
    SERVER.close()

客户端端：GUI聊天界面

客户端使用Tkinter库创建GUI界面，支持消息发送和接收。

7. 导入必要的库：

from socket import AF_INET, socket, SOCK_STREAM
from threading import Thread
import tkinter

2. 初始化GUI元素：

top = tkinter.Tk()
top.title("聊天室")
messages_frame = tkinter.Frame(top)
my_msg = tkinter.StringVar()
my_msg.set("输入你的消息。")

3. 消息列表和滚动条：

msg_list = tkinter.Listbox(messages_frame, height=15, width=50, yscrollcommand=scrollbar.set)
scrollbar.pack(side=tkinter.RIGHT, fill=tkinter.Y)
msg_list.pack(side=tkinter.LEFT, fill=tkinter.BOTH)
msg_list.pack()
messages_frame.pack()

4. 消息输入和发送功能：

entry_field = tkinter.Entry(top, textvariable=my_msg)
entry_field.bind("
           
            ", send)
entry_field.pack()
send_button = tkinter.Button(top, text="发送", command=send)
send_button.pack()
           

5. 连接到服务器并启动接收消息线程：

HOST = input("请输入服务器地址：")
PORT = input("请输入服务器端口：")
if not PORT:
    PORT = 33000
ADDR = (HOST, PORT)
client_socket = socket(AF_INET, SOCK_STREAM)
client_socket.connect(ADDR)
receive_thread = Thread(target=receive)
receive_thread.start()
tkinter.mainloop()

完整代码结构

• 服务器脚本：

#!/usr/bin/env python3
from socket import AF_INET, socket, SOCK_STREAM
from threading import Thread
BUFSIZ = 1024
ADDR = (input("请输入服务器地址："), int(input("请输入服务器端口：") or 33000))
SERVER = socket(AF_INET, SOCK_STREAM)
SERVER.bind(ADDR)
def accept_incoming_connections():
    while True:
        client, client_address = SERVER.accept()
        print(f"{client_address} 已连接。")
        client.send("欢迎来到聊天室！请输入你的名字并按回车。".encode("utf-8"))
        addresses[client] = client_address
        Thread(target=handle_client, args=(client,)).start()
def handle_client(client):
    name = client.recv(BUFSIZ).decode("utf-8")
    welcome = f"欢迎 {name}！输入 {quit} 退出。"
    client.send(welcome.encode("utf-8"))
    broadcast(f"{name} 已加入聊天。", name)
    clients[client] = name
    while True:
        msg = client.recv(BUFSIZ)
        if not msg:
            break
        if msg.decode("utf-8") == "{quit}":
            client.send("{quit}".encode("utf-8"))
            client.close()
            del clients[client]
            broadcast(f"{name} 已离开聊天。", name)
            break
        broadcast(f"{name}: {msg.decode('utf-8')}", name)
def broadcast(msg, prefix=""):
    for sock in clients:
        sock.send(f"{prefix}{msg}".encode("utf-8"))
if __name__ == "__main__":
    SERVER.listen(5)
    print("正在侦听连接...")
    accept_thread = Thread(target=accept_incoming_connections)
    accept_thread.start()
    accept_thread.join()
    SERVER.close()

• 客户端脚本：

#!/usr/bin/env python3
from socket import AF_INET, socket, SOCK_STREAM
from threading import Thread
import tkinter
top = tkinter.Tk()
top.title("聊天室")
messages_frame = tkinter.Frame(top)
my_msg = tkinter.StringVar()
my_msg.set("输入你的消息。")
scrollbar = tkinter.Scrollbar(messages_frame)
msg_list = tkinter.Listbox(messages_frame, height=15, width=50, yscrollcommand=scrollbar.set)
scrollbar.pack(side=tkinter.RIGHT, fill=tkinter.Y)
msg_list.pack(side=tkinter.LEFT, fill=tkinter.BOTH)
msg_list.pack()
messages_frame.pack()
entry_field = tkinter.Entry(top, textvariable=my_msg)
entry_field.bind("
            
             ", send)
entry_field.pack()
send_button = tkinter.Button(top, text="发送", command=send)
send_button.pack()
top.protocol("WM_DELETE_WINDOW", on_closing)
def send(event=None):
    msg = my_msg.get()
    my_msg.set("")
    if msg.strip() == "{quit}":
        client_socket.close()
        top.quit()
    else:
        client_socket.send(msg.encode("utf-8"))
        if msg:
            broadcast(msg, my_msg.get())
def on_closing(event=None):
    my_msg.set("{quit}")
    send()
HOST = input("请输入服务器地址：")
PORT = int(input("请输入服务器端口：") or 33000)
ADDR = (HOST, PORT)
client_socket = socket(AF_INET, SOCK_STREAM)
client_socket.connect(ADDR)
def receive():
    while True:
        try:
            msg = client_socket.recv(BUFSIZ).decode("utf-8")
            msg_list.insert(tkinter.END, msg)
        except OSError:
            break
receive_thread = Thread(target=receive)
receive_thread.start()
tkinter.mainloop()
            

通过以上代码，我们可以轻松搭建一个功能齐全的聊天应用程序。服务器端支持多人在线聊天，客户端提供友好的GUI界面。整个系统不依赖任何第三方库，完全由标准Python库驱动，实现了高效的消息传输和多线程处理。

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