s = socket.socket (socket_family, socket_type, protocol = 0)

#sever.py
import socket

s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
host = socket.gethostname()
port = 8088
s.bind((host,port))
try:
  while True:
    receive_data,addr = s.recvfrom(1024)
    print("来自服务器" + str(addr) + "的消息:")
    print(receive_data.decode('utf-8'))
    msg = input('please input send to msg:')
    s.sendto(msg.encode('utf-8'),addr)
except:
  s.close()

#client.py
import socket
s = socket.socket(socket.AF_INET,socket.SOCK_DGRAM)
try:
  while True:
    host = socket.gethostname()
    port = 8088
    send_data = input('please input msg:')
    s.sendto(send_data.encode('utf-8'),(host,port))
    msg,addr = s.recvfrom(1024)
    print("来自服务器" + str(addr) + "的消息:")
    print(msg.decode('utf-8'))
except:
  s.close()

#server.py
import socket
import logging

def main():
  s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) # 创建socket对象

  addr = ('127.0.0.1', 9999)
  s.bind(addr) # 绑定地址和端口

  logging.info('UDP Server on %s:%s...', addr[0], addr[1])

  user = {} # 存放字典{addr:name}
  while True:
    try:
      data, addr = s.recvfrom(1024) # 等待接收客户端消息存放在2个变量data和addr里
      if not addr in user: # 如果addr不在user字典里则执行以下代码
        for address in user: # 从user遍历数据出来address
          s.sendto(data + ' 进入聊天室...'.encode('utf-8'), address) # 发送user字典的data和address到客户端
        user[addr] = data.decode('utf-8') # 接收的消息解码成utf-8并存在字典user里,键名定义为addr
        continue # 如果addr在user字典里，跳过本次循环

      if 'EXIT'.lower() in data.decode('utf-8'):#如果EXIT在发送的data里
        name = user[addr]  #user字典addr键对应的值赋值给变量name
        user.pop(addr)   #删除user里的addr
        for address in user:  #从user取出address
          s.sendto((name + ' 离开了聊天室...').encode(), address)   #发送name和address到客户端
      else:  
        print('"%s" from %s:%s' %(data.decode('utf-8'), addr[0], addr[1])) 
        for address in user:  #从user遍历出address
          if address != addr: #address不等于addr时间执行下面的代码
            s.sendto(data, address)   #发送data和address到客户端

    except ConnectionResetError:
      logging.warning('Someone left unexcept.')

if __name__ == '__main__':
  main()

#clinet.py
import socket
import threading

def recv(sock, addr):
  '''
  一个UDP连接在接收消息前必须要让系统知道所占端口
  也就是需要send一次，否则win下会报错
  '''
  sock.sendto(name.encode('utf-8'), addr)
  while True:
    data = sock.recv(1024)
    print(data.decode('utf-8'))


def send(sock, addr):
  '''
    发送数据的方法
    参数：
      sock：定义一个实例化socket对象
      server：传递的服务器IP和端口
  '''
  while True:
    string = input('')
    message = name + ' : ' + string
    data = message.encode('utf-8')
    sock.sendto(data, addr)
    if string.lower() == 'EXIT'.lower():
      break

def main():
  '''
    主函数执行方法，通过多线程来实现多个客户端之间的通信
  '''
  s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
  server = ('127.0.0.1', 9999)
  tr = threading.Thread(target=recv, args=(s, server), daemon=True)
  ts = threading.Thread(target=send, args=(s, server))
  tr.start()
  ts.start()
  ts.join()
  s.close()

if __name__ == '__main__':
  print("-----欢迎来到聊天室,退出聊天室请输入'EXIT(不分大小写)'-----")
  name = input('请输入你的名称:')
  print('-----------------%s------------------' % name)
  main()