Python使用socket的UDP协议实现FTP文件服务

简介

　　本示例主要是用Python的socket，使用UDP协议实现一个FTP服务端、FTP客户端，用来实现文件的传输。在公司内网下，可以不适用U盘的情况下，纯粹使用网络，来实现文件服务器的搭建，进而实现文件的网络传输。同时用来理解Python的socket使用。

　　服务端运行起来后，会把服务器上面的指定目录作为根目录提供给客户端使用，即客户端可以访问、下载服务端设置的根目录里面的文件内容

　　客户端和服务端之间支持的一些简单命令如下：

• “ll”或者“ls”  查看当前目录下的所有文件或者目录
• “pwd”  查看当前所在的目录（根目录是服务端设置的“D:\var”目录）
• “get 文件名”  下载指定的文件到客户端配置的目录（客户端指定的根目录，在运行时配置）
• “get 目录”  下载指定的目录到客户端配置的目录
• “get all”  把当前所在的目录的所有文件、目录下载到客户端配置的目录
• “cd”  把客户端的目录切换到根目录
• “cd 目录” 把客户端的目录切换到指定的目录
• “cd ..” 把客户端的目录切换到上一级目录

　　客户端和服务端之间的通信，是把dict格式使用pickle.dumps()和pickle.loads()转成对应的bytes类型进行传输的。dict格式参考代码。

代码

file_handler.py

　　该文件就是把对文件的一些操作进行提取出来，供UDP服务端使用

import os
import logging
import traceback

LOG_FORMAT = "%(asctime)s - %(levelname)s [%(filename)s-%(funcName)s] Line: %(lineno)s] - %(message)s"
logging.basicConfig(level=logging.DEBUG, format=LOG_FORMAT)
_logger = logging.getLogger()

class FileHandler:
    def __init__(self, logger=None):
        """
        由于设置成可以支持自定义的logger，因此就没有设置成工具类形式，使用的时候，还是要实例化该类的
        :param logger:
        """
        self.__logger = logger if logger else _logger

    def list_dir(self, dir_path: str, return_absolute_path=False) -> list:
        """
        获取指定目录下面的文件或者目录的列表
        返回列表，里面中的每一个元素都是元组，元组的第一个值是文件或者目录名，第二个值是"d"(代表目录)或者"f"(代表文件)
        :param dir_path:
        :param return_absolute_path: True: 返回值是返回文件或者目录的绝对路径；  False: 只返回文件名或者目录名
        :return: [('download', 'd'), ('mylog.txt', 'f')]
        """
        ret_list = []
        try:
            if os.path.exists(dir_path):
                ret = os.listdir(dir_path)
                for item in ret:
                    if os.path.isdir(os.path.join(dir_path, item)):
                        if return_absolute_path:
                            ret_list.append((os.path.join(dir_path, item), 0, "d"))
                        else:
                            ret_list.append((item, 0, "d"))
                    if os.path.isfile(os.path.join(dir_path, item)):
                        size = os.path.getsize(os.path.join(dir_path, item))
                        if return_absolute_path:
                            ret_list.append((os.path.join(dir_path, item), size, "f"))
                        else:
                            ret_list.append((item, size, "f"))
        except Exception:
            self.__logger.error("Can not list dir: [%s]" % dir_path + traceback.format_exc())
        finally:
            return ret_list

    def seek_file(self, file_path: str, start_index: int, length=1024) -> tuple:
        """
        通过二进制格式读取指定一个文件指定范围的内容
        :param file_path:
        :param start_index:
        :param length: 读取的字节数
        :return:
        """
        # 下一次访问的时候的起始start_index值。 -1代表已经访问到文件结尾了，不用再访问该文件了。
        content_bytes = b''
        next_index = -1
        if not os.path.exists(file_path):
            message = "File[%s] not exists !!!" % file_path
            self.__logger.error(message)
            raise Exception(message)
        file_size = os.path.getsize(file_path)  # 文件大小

        if start_index >= file_size:
            return content_bytes, next_index
        try:
            # print("### file_size: ", file_size)
            with open(file_path, "rb") as fh:
                fh.seek(start_index)  # 游标跳到指定位置
                content_bytes = fh.read(length)  # 读取文件内容
                # print("content_bytes: ", content_bytes)
                # print("type(content_bytes): ", type(content_bytes))
                if start_index + length < file_size:
                    next_index = start_index + length
        except Exception:
            self.__logger.error("Seek file exception !!! " + traceback.format_exc())
        finally:
            return content_bytes, next_index

if __name__ == '__main__':
    file = r"D:\var\download\system.log"
    file_target = r"D:\var\download\system.txt"
    file = r"D:\软件安装包\NetAssist.exe"
    file_target = r"D:\软件安装包\NetAssist_copy.exe"
    file_obj = FileHandler()
    # ret = file_obj.seek_file(file, start_index=17, length=30)
    # print("ret: ", ret)
    # file_obj.copy_file(file, file_target, 1024 * 1000)

服务端代码

"""
    使用socket的udp协议实现的一个ftp服务端。
    服务器和客户端之间传递数据格式：
        1、服务端和客户端统一使用Python的字典格式（也就是本例中自定义的"通信协议"），格式形如：
            {
                "type": "cmd",  # 支持的值有： "cmd"、"download"
                "body": "ll",  # 在cmd模式下，常用的命令有: ll、ls、cd 指定目录、pwd
                "pwd": ["folder1", "folder2"],
                "status": 1,
                "uuid": "b93e21e659f711ee9285a46bb6f59f55"  # uuid.uuid1().hex，用来保证客户端和服务端
            }
        2、客户端使用pickle模块的pickle.dumps(dict类型数据)把要发送的数据转成bytes类型
        3、客户端使用socket的udp传输转成的bytes数据给服务端
        4、服务端接收到从客户端发送过来的bytes类型的数据，再使用pickle.loads(bytes类型数据)把数据转成原始的dict类型。

    使用socket的udp，既能接收数据，又能发送数据，因此服务端和客户端都是相对的。
"""

import os
import pickle
import sys
import socket
import logging
import time
import traceback
from file_handler import FileHandler

LOG_FORMAT = "%(asctime)s - %(levelname)s [%(filename)s-%(funcName)s] Line: %(lineno)s] - %(message)s"
logging.basicConfig(level=logging.DEBUG, format=LOG_FORMAT)
_logger = logging.getLogger()

_HOST = "127.0.0.1"
_PORT = 8090  # 服务器端口号
_ROOT_DIR = r"D:\var"  # 服务端给客户端展示的可以进行下载的文件路径

__all__ = ["FTPServerUDP"]

class FTPServerUDP:
    def __init__(self, host="", port=None, root_dir="", logger=None):
        self.__host = host if host else _HOST
        self.__port = port if port else _PORT
        self.__root_dir = root_dir if root_dir else _ROOT_DIR
        self.__logger = logger if logger else _logger
        self.__file_handler = FileHandler()

        self.__socket_obj = self.__get_socket_obj()

        self.__message_type_unsupported = "Unsupported message type"
        self.__message_type_server_inner_error = "Server internal error"
        self.__message_type_path_not_exists = "Target path not exists"
        self.__message_type_ok = "ok"

    def __get_socket_obj(self) -> socket.socket:
        socket_obj = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)  # UDP
        socket_obj.bind((self.__host, self.__port))  # 服务端必须绑定IP和端口
        return socket_obj

    def __message_handler(self, message_tuple: tuple):
        # 给客户端返回的数据类型，最终还需要使用pickle.dumps()把字典类型转成bytes类型进行发送
        response_message_dict = {
            "type": "cmd",
            "body": self.__message_type_unsupported,
            "pwd": [],  # 客户端的相对于服务端self.__root_dir的相对路径
            "status": 0  # 0:代表后端处理结果异常;   1:代表后端处理结果正常
        }

        recv_message_bytes = message_tuple[0]
        client_tuple = message_tuple[1]  # 客户端元组信息，形如 ('127.0.0.1', 59699)

        # 确保接收到的消息是 pickle.dumps() 转成的bytes类型，并把数据转成dict类型
        # recv_message_dict 的格式形如上面的response_message_dict格式
        recv_message_dict = self.__check_recv_message_type(recv_message_bytes)
        if not recv_message_dict:
            response_message_dict["body"] = self.__message_type_unsupported
            response_message_dict["status"] = 0
            self.__send_bytes_message(response_message_dict, client_tuple)
            return
        # 把客户端的进入的目录，赋值给返回值的目录。
        response_message_dict["pwd"] = recv_message_dict.get("pwd", [])

        # 把客户端传递进来的uuid，赋值给返回值的目录
        response_message_dict["uuid"] = recv_message_dict.get("uuid", "")

        # 接收到的消息符合规范，就需要根据"type"类型进行分类。
        try:
            print("recv_message_dict: ", recv_message_dict)
            if recv_message_dict.get("type", "") == "cmd":
                self.__cmd_handler(recv_message_dict, response_message_dict, client_tuple)
            elif recv_message_dict.get("type", "") == "download":
                self.__download_handler(recv_message_dict, response_message_dict, client_tuple)
            pass
        except Exception:
            self.__logger.error("Server message handler exception !!!" + traceback.format_exc())
            response_message_dict["status"] = 0
            response_message_dict["body"] = self.__message_type_server_inner_error
            self.__send_bytes_message(response_message_dict, client_tuple)

    def __check_recv_message_type(self, recv_message_bytes: bytes) -> dict:
        """
        确保接收到的消息是 pickle.dumps() 转成的bytes类型，并且通过pickle.loads()把bytes类型的数据转成dict后，
        dict类型数据中要有： "type"、"body"、"pwd"、"uuid" 等字段
        :param recv_message_bytes:
        :return:
        """
        ret_dict = {}
        try:
            message_dict = pickle.loads(recv_message_bytes)
        except Exception:
            return ret_dict

        if not isinstance(message_dict, dict):
            return ret_dict

        # 接收到的dict类型的消息中，必须要有如下的字段
        if not {"type", "body", "pwd", "uuid"}.issubset(set(message_dict.keys())):
            return ret_dict

        return message_dict

    def __send_bytes_message(self, message_dict: dict, client_tuple: tuple):
        """
            使用pickle.dumps()把字典格式的消息(message_dict)，转成bytes发送给客户端(client_tuple)
        :param message_dict:
        :param client_tuple:
        :return:
        """
        try:
            message_bytes = pickle.dumps(message_dict)
            self.__socket_obj.sendto(message_bytes, client_tuple)
        except Exception:
            self.__logger.error("Send message to client exception !!! " + traceback.format_exc())
            message_dict["status"] = 0
            message_dict["body"] = self.__message_type_server_inner_error
            message_bytes = pickle.dumps(message_dict)
            self.__socket_obj.sendto(message_bytes, client_tuple)

    def __cmd_handler(self, recv_message_dict: dict, response_message_dict: dict, client_tuple: tuple):
        """
        处理消息体的type参数值是"cmd"，这种命令行的消息
        :param recv_message_dict:
        :param response_message_dict:
        :param client_tuple:
        :return:
        """
        cmd_str = recv_message_dict.get("body", "").lower().strip()
        if not cmd_str or (not isinstance(cmd_str, str)):
            # 返回值形如: {'type': 'cmd', 'body': 'Unsupported message type', 'pwd': ['download']}
            response_message_dict["body"] = self.__message_type_unsupported
            response_message_dict["status"] = 0
            self.__send_bytes_message(response_message_dict, client_tuple)
            return

        if cmd_str in ("ls", "ll"):  # 查看当前目录的文件目录列表
            # 返回值形如: {'type': 'cmd', 'body': [('folder1', 'd'), ('file1.txt', 'f')]}
            customer_dir = self.__root_dir
            if recv_message_dict.get("pwd", []):
                customer_dir = os.path.join(self.__root_dir, *recv_message_dict.get("pwd", []))
            response_message_dict["body"] = self.__file_handler.list_dir(customer_dir)
            response_message_dict["status"] = 1  # 处理结果符合预期，状态设置成1
            self.__send_bytes_message(response_message_dict, client_tuple)
            return

        if cmd_str.startswith("cd"):  # 切换到下一个目录
            if cmd_str.strip() == "cd":
                response_message_dict["pwd"] = []
                response_message_dict["body"] = self.__message_type_ok
                response_message_dict["status"] = 1  # 处理结果符合预期，状态设置成1
                self.__send_bytes_message(response_message_dict, client_tuple)
                return

            target_dir = cmd_str.split(" ")[-1]
            if target_dir == "..":
                response_message_dict["pwd"] = response_message_dict["pwd"][0:-1]
                response_message_dict["body"] = self.__message_type_ok
                response_message_dict["status"] = 1  # 处理结果符合预期，状态设置成1
                self.__send_bytes_message(response_message_dict, client_tuple)
                return

            if target_dir == "/":
                response_message_dict["body"] = self.__message_type_ok
                response_message_dict["status"] = 1  # 处理结果符合预期，状态设置成1
                self.__send_bytes_message(response_message_dict, client_tuple)
                return
            if not os.path.exists(os.path.join(self.__root_dir, *recv_message_dict.get("pwd", []), target_dir)):
                # 返回值形如: {'type': 'cmd', 'body': 'Target path not exists', 'pwd': ['folder1']}
                response_message_dict["body"] = self.__message_type_path_not_exists
                response_message_dict["status"] = 0
                self.__send_bytes_message(response_message_dict, client_tuple)
                return
            elif not (os.path.join(self.__root_dir, *recv_message_dict.get("pwd", []), target_dir).startswith(self.__root_dir)):
                # 客户进入的目录，必须是以 self.__root_dir 开头，不能进入到其他目录
                # 返回值形如: {'type': 'cmd', 'body': 'Target path not exists', 'pwd': ['folder1']}
                # response_message_dict["pwd"] = []
                response_message_dict["body"] = self.__message_type_path_not_exists
                response_message_dict["status"] = 0
                self.__send_bytes_message(response_message_dict, client_tuple)
                return
            elif os.path.isfile(os.path.join(self.__root_dir, *recv_message_dict.get("pwd", []), target_dir)):  # 文件
                # 返回值形如: {'type': 'cmd', 'body': 'Target path not exists', 'pwd': ['folder1']}
                response_message_dict["body"] = self.__message_type_path_not_exists
                response_message_dict["status"] = 0
                self.__send_bytes_message(response_message_dict, client_tuple)
                return
            else:
                # 返回值形如： {'type': 'cmd', 'body': 'ok', 'pwd': ['folder1', 'folder2']}
                response_message_dict["pwd"].append(target_dir)
                response_message_dict["body"] = self.__message_type_ok
                response_message_dict["status"] = 1  # 处理结果符合预期，状态设置成1
                self.__send_bytes_message(response_message_dict, client_tuple)
                return

        if cmd_str == "pwd":
            # 返回值形如 {'type': 'cmd', 'body': ['folder1'], 'pwd': ['folder1']}
            response_message_dict["body"] = response_message_dict.get("pwd", [])
            response_message_dict["status"] = 1  # 处理结果符合预期，状态设置成1
            self.__send_bytes_message(response_message_dict, client_tuple)
            return

        self.__send_bytes_message(response_message_dict, client_tuple)
        return

    def __download_handler(self, recv_message_dict: dict, response_message_dict: dict, client_tuple: tuple):
        """
        处理消息体的type参数值是"download"，这种下载单个文件的命令行的消息
        :param recv_message_dict:
        :param response_message_dict:
        :param client_tuple:
        :return:
        """
        response_message_dict["type"] = "download"
        try:
            file_name = recv_message_dict["body"]["file_name"]  # 要下载的文件的名字
            pwd_list = recv_message_dict["pwd"]  # 要下载的文件所在的路径
            start_index = recv_message_dict["body"]["start_index"]  # 要下载的文件的起始位置索引
            length = recv_message_dict["body"]["length"]  # 单次下载的字节数
            if length > 1024 * 10:  # 单次传输的数据太大的话，会报错。通过测试，单次发送10KB数据比较合适。
                length = 1024 * 10
            file_name_absolute = os.path.join(self.__root_dir, *pwd_list, file_name)  # 要下载的文件的绝对路径

            content_bytes, next_index = self.__file_handler.seek_file(file_path=file_name_absolute,
                                                                      start_index=start_index,
                                                                      length=length)
            response_message_dict["body"] = {
                "file_name": file_name,
                "pwd": pwd_list,
                "content_bytes": content_bytes,
                "start_index": start_index,
                "next_index": next_index
            }
            response_message_dict["status"] = 1
            self.__send_bytes_message(response_message_dict, client_tuple)
        except Exception:
            response_message_dict["body"] = self.__message_type_server_inner_error
            response_message_dict["status"] = 0
            self.__logger.error("Download file exception !!!" + traceback.format_exc())
            self.__send_bytes_message(response_message_dict, client_tuple)

    def run(self):
        """
        调用该方法，启动服务端
        :return:
        """
        self.__logger.info("Server is running at [%s@%s], wating for client ..." % (self.__host, self.__port))
        while True:
            try:
                # message_tuple 是一个元组类型: (b'消息体', ('127.0.0.1', 61040))，第一个值是bytes类型的消息，第二个值是客户端信息
                message_tuple = self.__socket_obj.recvfrom(1024 * 1024)  # 从客户端接收到的消息
                self.__message_handler(message_tuple)
            except Exception:
                self.__logger.error("FTP Server Error: " + traceback.format_exc())
                time.sleep(1)

if __name__ == '__main__':
    ftp_server_obj = FTPServerUDP()
    ftp_server_obj.run()

客户端代码

"""
    使用socket的udp协议实现的一个ftp客户端。
    服务器和客户端之间传递数据格式：
        1、服务端和客户端统一使用Python的字典格式（也就是本例中自定义的"通信协议"），格式形如：
            {
                "type": "cmd",  # 支持的值有： "cmd"、"download"
                "body": "ll",  # 在cmd模式下，常用的命令有: ll、ls、cd 指定目录、pwd
                "pwd": ["folder1", "folder2"],
                "status": 1,
                "uuid": "b93e21e659f711ee9285a46bb6f59f55"  # uuid.uuid1().hex，用来保证客户端和服务端
            }
        2、客户端使用pickle模块的pickle.dumps(dict类型数据)把要发送的数据转成bytes类型
        3、客户端使用socket的udp传输转成的bytes数据给服务端
        4、服务端接收到从客户端发送过来的bytes类型的数据，再使用pickle.loads(bytes类型数据)把数据转成原始的dict类型。

    使用socket的udp，既能接收数据，又能发送数据，因此服务端和客户端都是相对的。
"""

import socket
import sys
import time
import pickle
import os
import logging
import traceback
import uuid

LOG_FORMAT = "%(asctime)s - %(levelname)s [%(filename)s-%(funcName)s] Line: %(lineno)s] - %(message)s"
logging.basicConfig(level=logging.DEBUG, format=LOG_FORMAT)
_logger = logging.getLogger()

class FTPClientUDP:
    def __init__(self, host="127.0.0.1", port=8090, download_path="D:\my_download", logger=None):
        self.__host = host  # 服务器的IP地址
        self.__port = port  # 服务器的端口号
        self.__download_root_path = download_path  # 要下载的文件路径
        self.__logger = logger if logger else _logger
        if not os.path.exists(download_path):
            os.makedirs(download_path, True)

        self.__socket_obj = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)  # UDP连接对象
        self.__is_downloading = False  # 用来标识是否在下载文件，当在下载文件的时候，就不会再接收输入参数
        self.__pwd_list = []  # 用来存储用户所在的当前目录
        self.__server_tuple = (self.__host, self.__port)  # 服务端的地址和端口号组成的元组

    def __cmd_handler(self, cmd_dict: dict):
        """

        :param cmd_dict: 形如：{'type': 'cmd', 'body': 'll', 'pwd': [], 'status': 1,
                               'uuid': 'f5c2f4d263f111ee877aa46bb6f59f55'}
        :return:
        """
        # print("cmd_dict: ", cmd_dict)
        cmd_bytes = pickle.dumps(cmd_dict)
        if cmd_dict["body"] in ["ll", "ls"]:
            self.__cmd_handler_ls(cmd_dict, cmd_bytes)
        elif cmd_dict["body"].startswith("cd "):
            self.__cmd_handler_cd(cmd_dict, cmd_bytes)
        elif cmd_dict["body"] == "pwd":
            self.__cmd_handler_pwd(cmd_dict, cmd_bytes)
        elif cmd_dict["body"].startswith("get "):
            self.__cmd_handler_get(cmd_dict, cmd_bytes)
        else:
            print("Command [%s] not supported !!!" % cmd_dict["body"])
            print()

    def __cmd_handler_ls(self, cmd_dict: dict, cmd_bytes: bytes):
        """
        发送类似于"ls -la" 命令给服务端，并把返回值打印到终端
        :param cmd_dict:
        :param cmd_bytes:
        :return:
        """
        recv_message_dict = self.__recv_normal_cmd_handler(cmd_dict, cmd_bytes)
        self.__print_normal_info(recv_message_dict)

    def __cmd_handler_cd(self, cmd_dict: dict, cmd_bytes: bytes):
        """
        发送类似于"cd 指定目录"命令给服务端，并把返回值打印到终端
        :param cmd_dict:
        :param cmd_bytes:
        :return:
        """
        recv_message_dict = self.__recv_normal_cmd_handler(cmd_dict, cmd_bytes)
        self.__print_normal_info(recv_message_dict)
        if recv_message_dict.get("status", 0):
            self.__pwd_list = recv_message_dict["pwd"]  # 保存客户端进入的目录

    def __cmd_handler_pwd(self, cmd_dict: dict, cmd_bytes: bytes):
        """
        发送 "pwd" 命令给服务端，并把返回值打印到终端
        :param cmd_dict:
        :param cmd_bytes:
        :return:
        """
        recv_message_dict = self.__recv_normal_cmd_handler(cmd_dict, cmd_bytes)
        self.__print_pwd_info(recv_message_dict)
        if recv_message_dict.get("status", 0):
            self.__pwd_list = recv_message_dict["pwd"]  # 保存客户端进入的目录

    def __cmd_handler_get(self, cmd_dict: dict, cmd_bytes: bytes):
        # 获取当前目录下面的所有的文件，包括文件夹
        if cmd_dict["body"].lower().strip() == "get all":
            self.__download_handler_all_file()
            return

        # 获取当前目录下面"get "命令后面的一个文件
        command = cmd_dict["body"]
        file_name = cmd_dict["body"].split(" ")[-1]  # 字符串类型的要下载的文件名
        if not file_name:
            return
        # 首先获取当前目录"ll"的返回值
        cmd_dict_ll = {'type': 'cmd',
                       'body': 'll',
                       'pwd': cmd_dict["pwd"],
                       'status': 1,
                       'uuid': uuid.uuid1().hex
                       }
        ret_dict = self.__recv_normal_cmd_handler(cmd_dict_ll)
        can_download = False
        file_size = 0  # 文件大小
        pwd = []  # 文件所处路径
        file_type = "f"  # f:文件   d:目录
        for item_tuple in ret_dict["body"]:  # item_tuple形如 ('aa.txt', 34, 'f')
            if item_tuple[0] == file_name:
                can_download = True
                file_size = item_tuple[1]
                pwd = ret_dict["pwd"]
                file_type = item_tuple[-1]
        if can_download and file_type == "f":
            self.__download_handler_one_file(file_name, file_size, pwd)
            print()
        if can_download and file_type == "d":
            raw_pwd = self.__pwd_list  # 存储用户最原始的pwd目录。
            self.__download_handler_one_folder(file_name, pwd)
            self.__pwd_list = raw_pwd  # 把用户最原始的pwd目录再重新赋给self.__pwd_list变量中。
        else:
            print()

    def __download_handler_one_file(self, file_name: str, file_size=0, pwd=[]):
        # 发送下载单个文件的命令格式，下载的时候，要来回更新 download_cmd_dict['body']['start_index']的值
        download_cmd_dict = {
            'type': 'download',
            'body': {
                "file_name": file_name,
                "pwd": pwd,
                "start_index": 0,  #
                "length": 1024 * 1024  # 使用UDP传输的数据，单次数据太大的话会报错
            },
            'pwd': pwd,
            'status': 1,
            'uuid': uuid.uuid1().hex
        }
        try:
            file_absolute = os.path.join(self.__download_root_path, *pwd, file_name)
            if not os.path.exists(os.path.dirname(file_absolute)):
                os.mkdir(os.path.dirname(file_absolute))
            with open(file_absolute, "wb") as fh:
                while True:
                    download_cmd_bytes = pickle.dumps(download_cmd_dict)
                    ret_dict = self.__recv_normal_cmd_handler(download_cmd_dict, download_cmd_bytes)
                    if not ret_dict["status"]:  # 下载途中失败了
                        self.__logger.error("Download exception: " + str(ret_dict["body"]))
                        break
                    fh.write(ret_dict["body"]["content_bytes"])
                    next_index = ret_dict["body"]["next_index"]
                    if ret_dict["body"]["next_index"] == -1:  # 说明已经把文件下载完了
                        break

                    download_cmd_dict["body"]["start_index"] = ret_dict["body"]["next_index"]
                    download_cmd_dict["uuid"] = uuid.uuid1().hex
                    self.__print_download_info(file_absolute, file_size, next_index)
                self.__print_download_successfully_info(file_absolute)
        except Exception:
            self.__logger.error("Download file exception !!!" + traceback.format_exc())

    def __download_handler_one_folder(self, file_name: str, pwd=[]):
        """
        下载一个文件夹。
        :param file_name: 即文件夹名字。进入到该方法，默认文件名是存在的
        :param pwd:
        :return:
        """
        if not os.path.exists(os.path.join(self.__download_root_path, *pwd, file_name)):
            os.makedirs(os.path.join(self.__download_root_path, *pwd, file_name))

        cmd_dict_ll = {'type': 'cmd',
                       'body': 'll',
                       'pwd': pwd,  # 该参数会在后面的代码中进行替换更新
                       'status': 1,
                       'uuid': uuid.uuid1().hex
                       }
        cmd_dict_cd = {'type': 'cmd',
                       'body': 'cd ' + file_name,  # 进入到的目录
                       'pwd': pwd,
                       'status': 1,
                       'uuid': uuid.uuid1().hex
                       }

        # 先进入指定目录
        recv_message_dict_cd = self.__recv_normal_cmd_handler(cmd_dict_cd, None)
        pwd = recv_message_dict_cd["pwd"]  # 保存进入的目录
        # 获取指定目录的文件列表
        cmd_dict_ll["pwd"] = pwd
        recv_message_dict_ll = self.__recv_normal_cmd_handler(cmd_dict_ll, None)
        # print("&&&&&&&v recv_message_dict_ll: ", recv_message_dict_ll)
        if recv_message_dict_ll["status"] and recv_message_dict_ll["body"]:
            for item_tuple in recv_message_dict_ll["body"]:
                # print("@@@@ item_tuple: ", item_tuple)
                if item_tuple[-1] == "f":
                    self.__download_handler_one_file(file_name=item_tuple[0],
                                                     file_size=item_tuple[1],
                                                     pwd=pwd
                                                     )
                elif item_tuple[-1] == "d":
                    self.__download_handler_one_folder(file_name=item_tuple[0],
                                                       pwd=pwd)

    def __download_handler_all_file(self):
        """
        下载当前目录下面的所有文件及文件夹
        :return:
        """
        if not os.path.exists(os.path.join(self.__download_root_path, *self.__pwd_list)):
            os.makedirs(os.path.join(self.__download_root_path, *self.__pwd_list))

        cmd_dict_ll = {'type': 'cmd',
                       'body': 'll',
                       'pwd': self.__pwd_list,  # 该参数会在后面的代码中进行替换更新
                       'status': 1,
                       'uuid': uuid.uuid1().hex
                       }
        recv_message_dict_ll = self.__recv_normal_cmd_handler(cmd_dict_ll, None)
        if recv_message_dict_ll["status"] and recv_message_dict_ll["body"]:
            for item_tuple in recv_message_dict_ll["body"]:
                if item_tuple[-1] == "f":
                    self.__download_handler_one_file(file_name=item_tuple[0],
                                                     file_size=item_tuple[1],
                                                     pwd=recv_message_dict_ll["pwd"]
                                                     )
                elif item_tuple[-1] == "d":
                    self.__download_handler_one_folder(file_name=item_tuple[0],
                                                       pwd=recv_message_dict_ll["pwd"]
                                                       )

    def __recv_normal_cmd_handler(self, cmd_dict: dict, cmd_bytes: bytes=None, try_times=3) -> dict:
        """
        持续发送一条命令到客户端，直到正常接收到数据后结束
        :param cmd_dict: 形如 {'type': 'cmd', 'body': 'get aa.txt', 'pwd': [], 'status': 1,
                               'uuid': '464899225dcb11ee9a91a46bb6f59f55'}
        :param cmd_bytes:
        :param try_times: 重试的次数，即

        :return:  形如 {'type': 'cmd', 'body': [('log', 0, 'd'), ('mylog.txt', 8, 'f')],
                        'pwd': [], 'status': 1, 'uuid': '464899235dcb11eebf99a46bb6f59f55'}
                 或者 {'type': 'cmd', 'body': {'file_name': 'logger.log', 'pwd': ['log'], 'content_bytes': b'2023-',
                                              'start_index': 0, 'next_index': 5},
                        'pwd': [], 'status': 1, 'uuid': '464899235dcb11eebf99a46bb6f59f55'}
        """
        ret_dict = {}
        cmd_bytes = cmd_bytes if cmd_bytes else pickle.dumps(cmd_dict)
        try:
            for x in range(try_times):
                # print("cmd_dict_ll: ", cmd_dict)
                self.__socket_obj.sendto(cmd_bytes, self.__server_tuple)  # 服务器端的地址
                recv_message_tuple = self.__socket_obj.recvfrom(1024 * 1024)
                recv_message_bytes = recv_message_tuple[0]
                recv_message_dict = pickle.loads(recv_message_bytes)
                if cmd_dict.get("uuid", "False") == recv_message_dict.get("uuid", "True"):
                    ret_dict = recv_message_dict
                    break
                time.sleep(0.1)
        except Exception:
            self.__logger.error("Recv normal cmd info exception !!!" + traceback.format_exc())
        finally:
            return ret_dict

    def __print_normal_info(self, recv_message_dict: dict):
        message_body = recv_message_dict.get("body", None)
        if isinstance(message_body, list):
            for item in message_body:
                print("%-20s %-20s %-20s" % (item[0], item[1], item[2]))
            print()
            return True
        if isinstance(message_body, str):
            print("%-20s" % message_body)
            print()
            return True
        return True

    def __print_pwd_info(self, recv_message_dict: dict):
        pwd_list = recv_message_dict.get("pwd", [])
        if not pwd_list:
            print("%-20s" % "/")
        else:
            pwd_str = '/' + '/'.join(pwd_list)
            print("%-20s" % pwd_str)
        print()
        return True

    def __print_download_info(self, file_name, file_size, next_index):
        sys.stdout.write("\r[%s] -->: %s" % (file_name, ("%.3f" % (next_index / file_size* 100) + "%")))

    def __print_download_successfully_info(self, file_name):
        """
        最终打印100%
        :param file_name:
        :return:
        """
        sys.stdout.write("\r[%s] -->: %s" % (file_name, "100%"))
        print()

    def run(self):
        while True:
            try:
                # 没有下载任务的话，则接收输入新的命令
                if not self.__is_downloading:
                    cmd = input("Input: ")
                    cmd_dict = {
                        "type": "cmd",
                        "body": cmd,
                        "pwd": self.__pwd_list,
                        "status": 1,
                        "uuid": uuid.uuid1().hex
                    }
                    self.__cmd_handler(cmd_dict)
                    print("================================================")
                else:
                    time.sleep(1)
            except Exception:
                self.__logger.error("Client exception: " + traceback.format_exc())
                time.sleep(1)

if __name__ == '__main__':
    ftp_client_obj = FTPClientUDP()
    ftp_client_obj.run()

使用

先运行服务端代码，再运行客户端代码。然后再在客户端输入响应的命令即可