从某宝上购买了一份《Python神经网络深度学习》课程，按照视频教程，用python语言，写了一个简易的FTP服务端和客户端程序，以前也用C++写过聊天程序，编程思路差不多，但是python编程时更顺畅，代码量更少。没有很高深的理论知识，也不需要扎实的编程基础，知道需要用哪些库就行了。
两种语言对比，初次感受到python语言的易用之处，python的核心是简洁清晰，也是伪代码的最佳实践语言。可以理解为C语言的一些常用功能库的转义，所以普遍认为python语言带来编程便捷的同时，也会带来一部分性能的牺牲。但这并不也是绝对的，有时候程序的开发效率更为重要，更何况并不一定人人都是大牛，用C或者其它语言未必就能写出比python更高性能的代码。整体学习完以后，还会再来深入对比下python和其他语言的差异。
１、基本功能
登陆验证
上传：支持断点上传，MD５验证
简单命令：cd、ls、mkdir
2、常用模块
下面是我汇总的用到的模块信息，要写出完整的代码，首先得了解基本的python函数和库，例如：
os，sys库对目录和文件的处理；
socket和socketserver对网络通信的处理；
json对传输数据格式的处理；
configparse对配置文件的处理；
hashlib对MD5校验的处理；
optparse对命令行输入参数的格式化处理等；
另外还需要了解如何利用反射机制，处理多If else分支的函数调用等。
关于python反射机制，参考链接：https://www.cnblogs.com/Guido-admirers/p/6206212.html
3、具体代码
ftp_client.py：FTP客户端主程序
import socket import optparse import json import os,sys import hashlib STATUS_CODE = { 250 : "Invalid cmd format, e.g: {'action':'get','filename':'test.py','size':344}", 251 : "Invalid cmd ", 252 : "Invalid auth data", 253 : "Wrong username or password", 254 : "Passed authentication", 255 : "Filename doesn't provided", 256 : "File doesn't exist on server", 257 : "ready to send file", 258 : "md5 verification", 800 : "the file exist,but not enough ,is continue? ", 801 : "the file exist !", 802 : " ready to receive datas", 900 : "md5 valdate success" } sk = socket.socket() sk.connect(("127.0.0.1",18000)) class ClientHander(): def __init__(self): #初始化变量 self.op = optparse.OptionParser() self.op.add_option("-s","--server",dest="server") self.op.add_option("-P", "--port", dest="port") self.op.add_option("-u", "--username", dest="username") self.op.add_option("-p", "--password", dest="password") self.options,self.args = self.op.parse_args() #self.verify_args(self.options,self.args) self.mainPath = os.path.dirname(os.path.abspath(__file__)) self.last = 0 self.is_authenticated = False self.is_connected = False self.is_needed_md5 = True #开始建立连接 self.make_connection() # 验证用户输入信息 def verify_args(self,options,args): server = options.server port = options.port username = options.username password = options.password if int(port) > 0 and int(port) < 65535: return True else: exit("the port should been in 0-65535") # 连接服务器 def make_connection(self): if not self.is_connected: self.sock = socket.socket() self.sock.connect(("127.0.0.1", 18000)) self.is_connected = True return def interactive(self): # 判断是否已经验证过 if not self.is_authenticated: self.make_connection() self.authenticate() # 开始和服务器进行交互 cmd_info = input("[%s]"%self.current_dir).strip() # 利用反射机制，建立命令与功能对应关系 cmd_list = cmd_info.split() if hasattr(self,cmd_list[0]): func = getattr(self,cmd_list[0]) func(*cmd_list) def authenticate(self): if not self.is_connected: print("没有连接FTP服务器") return if self.options.username is None or self.options.password is None: username = input("username:") password = input("password:") return self.get_auth_result(username,password) return self.get_auth_result(self.options.username,self.options.password) def response(self): data = self.sock.recv(1024).decode("utf-8") data = json.loads(data) return data def get_auth_result(self,username,password): data = { "action":"auth", "username":username, "password":password } self.sock.send(json.dumps(data).encode("utf-8")) res = self.response() print("res",res["status_code"]) if res["status_code"] == 254: self.username = username self.current_dir = username self.is_authenticated = True print(STATUS_CODE[254]) return True else: print(STATUS_CODE[res["status_code"]]) def put(self,*cmd_list): # 1 发送上传命令 action,local_path,target_path = cmd_list local_path = os.path.join(self.mainPath,local_path) file_name = os.path.basename(local_path) file_size = os.stat(local_path).st_size data = { "action":"put", "file_name": file_name, "file_size": file_size, "target_path": target_path } self.sock.sendall(json.dumps(data).encode("utf-8")) # 2 接收服务器检查结果 has_sent = 0 is_exsit = self.sock.recv(1024).decode("utf-8") # 3 根据服务器检查结果，执行相应命令 # 文件存在但不完整 if is_exsit == "800": print("服务器文件已经存在，且不完整") # 和服务器确认是否继续上传 choice = input("The file exist but not enough,is continue?[Y/N]").strip() # 继续上传 if choice.upper() == "Y": self.sock.sendall("Y".encode("utf-8")) # 等待服务器返回存在文件大小 continue_position = self.sock.recv(1024).decode("utf-8") has_sent += int(continue_position) # 不继续上传 else: self.sock.sendall("N".encode("utf-8")) # 文件存在且完整 elif is_exsit == "801": print("服务器文件已经存在，且完整") return f = open(local_path,"rb") f.seek(has_sent) md5_obj = None if self.is_needed_md5: md5_obj = hashlib.md5() while has_sent < file_size: data = f.read(1024) self.sock.sendall(data) if md5_obj: md5_obj.update(data) has_sent += len(data) mdt_val_server = self.sock.recv(1024).decode("utf-8") mdt_val_client = md5_obj.hexdigest() self.show_progress(has_sent,file_size) print("client's md5 is %s"%mdt_val_client) print("server's md5 is %s" %mdt_val_server) f.close() if mdt_val_client == mdt_val_server: print("put success") else: print("Athenticate MD5 failed.") def show_progress(self,has,total): rate = float(has) / float(total) rate_num = int(rate*100) print("%s%% %s\r"%(rate_num,"#"*rate_num)) def ls(self,*cmd_list): data = { "action":"ls" } self.sock.sendall(json.dumps(data).encode("utf-8")) data = self.sock.recv(1024).decode("utf-8") print(data) def cd(self,*cmd_list): # cd images data = { "action":"cd", "dirname":cmd_list[1] } self.sock.sendall(json.dumps(data).encode("utf-8")) data = self.sock.recv(1024).decode("utf-8") self.current_dir = os.path.basename(data) print(os.path.basename(data)) def mkdir(self,*cmd_list): data = { "action":"mkdir", "dirname":cmd_list[1] } self.sock.sendall(json.dumps(data).encode("utf-8")) data = self.sock.recv(1024).decode("utf-8") print(data) ch = ClientHander() while 1: ch.interactive()