import socketserver
import os
import json
import struct

class MyRequestHandle(socketserver.BaseRequestHandler):
    def handle(self):
        # 如果tcp协议，self.request=>conn
        print(self.client_address)
        while True:
            try:
                file_name = self.request.recv(1024)
                # 拼接文件路径
                dir_name = os.path.dirname(__file__)
                file_path = os.path.join(dir_name,file_name)
                # 读取文件，若为空则返回空给客户端
                with open(file_path,mode="rb") as f:
                    res = f.read()
                    total_size = len(res)
                if total_size == 0:
                    res = "None".encode("utf-8")
                    total_size = len(res)
                    file_name = "Error:file has no content!"

                # 1、制作头
                header_dic = {
                    "filename": file_name,
                    "total_size": total_size,
                    "md5": "123123xi12ix12"
                }

                json_str = json.dumps(header_dic)
                json_str_bytes = json_str.encode(‘utf-8‘)

                # 2、先把头的长度发过去
                x = struct.pack(‘i‘, len(json_str_bytes))
                self.request.send(x)

                # 3、发头信息
                self.request.send(json_str_bytes)
                # 4、再发真实的数据
                self.request.send(res)

            except Exception:
                break
        self.request.close()

#  服务端应该做两件事
# 第一件事：循环地从半连接池中取出链接请求与其建立双向链接，拿到链接对象
s=socketserver.ThreadingTCPServer((‘0.0.0.0‘,8888),MyRequestHandle)
s.serve_forever()

from socket import *

client=socket(AF_INET,SOCK_STREAM)
client.connect((‘39.97.179.91‘,8888))

while True:
    msg=input(‘请输入需要下载的文件名：‘).strip()
    if len(msg) == 0:continue
    client.send(msg.encode(‘utf-8‘))

    res=client.recv(1024)
    print(res.decode(‘utf-8‘))