selectors模块介绍

import selectors # python封装的一个IO多路复用的模块，会根据系统的不同而选择不同的方法(select/epoll/poll)
from socket import *

sel = selectors.DefaultSelector() # 首先DefaultSelector()实例化一个对象

def accept(sock, mask):
    '''当有连接请求时，sock发生了变化，执行此函数'''
    conn, addr = sock.accept()
    print('accepted：', conn, 'from：', addr)
    conn.setblocking(False) # 将conn设置为非阻塞状态
    sel.register(conn, selectors.EVENT_READ, read) # 将conn添加进监听列表，conn和read(自己写的read方法)做了一个绑定

def read(conn, mask):
    '''当conn发生变化时，执行此函数'''
    try:
        data = conn.recv(1024)
        # 当客户端输入为空时，不知道怎么办(在这里做为空判断没有用)！没有监听到吗还是什么其它原因呢？
        if data:
            print('echoing：', repr(data), 'to：', conn)
            conn.send(data)
        else:
            print('输入完毕退出...')
            sel.unregister(conn) # 将conn移出监听列表
            conn.close()
    except Exception:
        print('closing：', conn)
        sel.unregister(conn) # # 将conn移出监听列表
        conn.close()

sock = socket(AF_INET, SOCK_STREAM)
sock.bind(('127.0.0.1', 8080))
sock.listen(10)
sock.setblocking(False) # 设置为非阻塞状态

sel.register(sock, selectors.EVENT_READ, accept)
# 先将sock添加进监听列表，sock和accept(自己写的accept方法)做了一个绑定

while True:
    events = sel.select()
    # select进行监听
    print('events:', events)
    # events: [(SelectorKey(fileobj=<socket.socket fd=460, family=AddressFamily.AF_INET, type=SocketKind.SOCK_STREAM, proto=0, laddr=('127.0.0.1', 8080)>, fd=460, events=1, data=<function accept at 0x0000021117343040>), 1)]
    # events: [(SelectorKey(fileobj=<socket.socket fd=120, family=AddressFamily.AF_INET, type=SocketKind.SOCK_STREAM, proto=0, laddr=('127.0.0.1', 8080), raddr=('127.0.0.1', 60268)>, fd=120, events=1, data=<function read at 0x0000021117558E50>), 1)]
    for key, mask in events:
        # print(type(key))
        # <class 'selectors.SelectorKey'>
        print('key:', key)
        # key: SelectorKey(fileobj=<socket.socket fd=460, family=AddressFamily.AF_INET, type=SocketKind.SOCK_STREAM, proto=0, laddr=('127.0.0.1', 8080)>, fd=460, events=1, data=<function accept at 0x0000021117343040>)
        # key: SelectorKey(fileobj=<socket.socket fd=120, family=AddressFamily.AF_INET, type=SocketKind.SOCK_STREAM, proto=0, laddr=('127.0.0.1', 8080), raddr=('127.0.0.1', 60268)>, fd=120, events=1, data=<function read at 0x0000021117558E50>)
        print('mask:', mask)
        # mask: 1
        # mask: 1
        callback = key.data # <function accept at 0x0000021117343040>/<function read at 0x0000021117558E50>
        callback(key.fileobj, mask)
        # key.fileobj:<socket.socket fd=460, family=AddressFamily.AF_INET, type=SocketKind.SOCK_STREAM, proto=0, laddr=('127.0.0.1', 8080)>
        # key.fileobj:<socket.socket fd=120, family=AddressFamily.AF_INET, type=SocketKind.SOCK_STREAM, proto=0, laddr=('127.0.0.1', 8080), raddr=('127.0.0.1', 60268)>
        # 第一行为服务端的sock(socket对象)，第二行为客户端连接的conn(客户端的socket对象)

from socket import *

cl = socket(AF_INET, SOCK_STREAM)

cl.connect(('127.0.0.1', 8080))

msg = input('输入：')
cl.sendall(msg.encode('utf-8'))

data = cl.recv(1024)
print(data.decode('utf-8'))