python学习笔记

一、Socket

当服务端传的东西大于客户端的最大值时怎么办？①改大buffer不行（有上限）②多传几次(用for循环必须要知道循环几次，所以不用for循环，用while)

服务端：

 import os

 import socket

 server=socket.socket()

 server.bind(("localhost",9999))

 server.listen()

 while True:

     conn,addr=server.accept()

     print("new conn:",addr)

     while True:

         print("等待新指令")

         data=conn.recv(700)

         if not data :

             print("客户端已断开")

             break

         print("执行指令:",data)

         cmd_res=os.popen(data.decode()).read() #接受字符串，执行结果也是字符串

         print("before send",len(cmd_res.encode()))

         if len(cmd_res)==0:

             cmd_res="cmd has no output..."

         conn.send(str(len(cmd_res.encode())).encode("utf-8")) #先发大小给客户端

         #字符串才能encode，cmd_res要encode 否则因为中文的原因长度会不相等

         conn.send(cmd_res.encode("utf-8"))

         print("send done")

 server.close()

客户端：

 import socket

 client=socket.socket()

 client.connect(("localhost",9999))

 while True:

     cmd=input(">>:").strip()

     if len(cmd) == 0 :

         continue

     client.send(cmd.encode("utf-8"))

     cmd_res_size=client.recv(700) #接收命定结果的长度

     print("命令结果:",cmd_res_size)

     received_size=0

     received_data=b""

     while received_size != int(cmd_res_size.decode()):

         data=client.recv(700)

         received_size+=len(data) #每次收到的有可能小于700，所以必须用len判断

         # print(data.decode())

         received_data+=data

     else:

         print("cmd res receive done",received_size)

     # cmd_res=client.recv(700)

         print(received_data.decode())

 client.close()

socket粘包：两次send紧挨着，缓冲区将其打包成一次send，导致出错（用time.sleep()解决太low了，不要用），可以在两次send间插入一次交互，如在服务器端client_ack=conn.recv(700) #wait client to confirm,在客户端client.send("准备好接收了，loser可以发了".encode("utf-8")) PS:windows上粘包现象可能不会显示出来，但Linux一定会。

ftp server:1.读取文件名；2.检测文件是否存在；3.打开文件；4.检测文件大小；5.发送文件大小给客户端；6.等客户端确认；7.开始边读边发数据；8.发送md5；

服务端：

 import hashlib

 import os

 import socket

 server=socket.socket()

 server.bind(("localhost",9999))

 server.listen()

 while True:

     conn,addr=server.accept()

     print("new conn:",addr)

     while True:

         print("等待新指令")

         data=conn.recv(700)

         if not data :

             print("客户端已断开")

             break

         cmd,filename=data.decode().split()

         print(filename)

         if os.path.isfile(filename): #判断文件是否存在

             f=open(filename,"rb")

             m=hashlib.md5()

             file_size=os.stat(filename).st_size #文件大小

             conn.send(str(file_size).encode()) #send file size

             conn.recv(700) #wait for ack

             for line in f:

                 m.update(line)

                 conn.send(line)

             print("file md5",m.hexdigest()) #加上md5速度会慢下来

             f.close()

             conn.send(m.hexdigest().encode()) #send md5

         print("send done")

 server.close()

客户端：

 import socket

 import hashlib

 client=socket.socket()

 client.connect(("localhost",9999))

 while True:

     cmd=input(">>:").strip()

     if len(cmd) == 0 :

         continue

     if cmd.startswith("get"):

         client.send(cmd.encode())

         server_response=client.recv(700)

         print("server response",server_response)

         client.send(b"ready to recv file")

         file_total_size=int(server_response.decode())

         received_size=0

         filename=cmd.split()[1]

         f=open(filename+".new","wb")

         m=hashlib.md5()

         while received_size < file_total_size:

             if file_total_size - received_size > 700:#要收不止一次

                 size=700

             else: #最后一次了，剩多少就只收多少

                 size=file_total_size-received_size

 #上面的判断是为了防止粘包。粘包只可能发生在最后一次

                 print("last receive:",size)

             data=client.recv(size)

             received_size+=len(data)

             m.update(data)

             f.write(data)

             #print(file_total_size,received_size)

         else:

             new_file_md5=m.hexdigest()

             print("file recv done",file_total_size,received_size)

             f.close()

         server_file_md5=client.recv(700)

         print("server file md5:",server_file_md5)

         print("client file md5:",new_file_md5)

 client.close()

二、Socketsever

最主要的作用：并发处理。定义：简化网络任务服务器端的编写（对socket的再封装）

1.socketserver.TCPServer；2.socketserver.UDPServer；3.socketserver.UnixStreamServer；4.socketserver.UnixDatagramServer

创建SocketServer的步骤：

1.你必须自己创建一个请求处理类，并且这个类要继承BaseRequestHandler，并且还要重写父类里的handle()。

2.你必须实例化TCPserver（其他也行），并且传递server ip 和你上面创建的请求处理类给这个TCPserver。

3.server.handle_request() #只处理一个请求（不常用）

　server.handle_forever()#处理多个请求，永远执行

调用server_close()来关闭

跟客户端所有的交互都是在handle里完成的

 import socketserver

 class MyTCPHandler(socketserver.BaseRequestHandler):

     """

     The request handler class for our server.

     It is instantiated once per connection to the server, and must

     override the handle() method to implement communication to the

     client.

     """

     def handle(self):

         while True:

             try:

                 # self.request is the TCP socket connected to the client

                 self.data = self.request.recv(1024).strip() #每一个客户端的请求过来都会实例化MyTCPHandler

                 print("{} wrote:".format(self.client_address[0]))

                 print(self.data)

                 # if not self.data:#客户端断了

                 #     print(self.client_address,"断开了")

                 #     break

                 # just send back the same data, but upper-cased

                 self.request.send(self.data.upper())

             except ConnectionResetError as e:

                 print("err:",e)

                 break

 if __name__ == "__main__":

     HOST, PORT = "localhost", 9999

     # Create the server, binding to localhost on port 9999

     server = socketserver.TCPServer((HOST, PORT), MyTCPHandler) #把ip地址和类当做参数传给TCPServer,TCPServer就开始监听

     # 和实例化MyTCPHandler，拿handle()与客户端交互

     # Activate the server; this will keep running until you

     # interrupt the program with Ctrl-C

     server.serve_forever()

多并发：每来一个请求，开启一个新线程。

让你的socketserver并发起来，必须选择使用以下一个多并发的类

class socketserver.ForkingTCPServer

class socketserver.ForkingUDPServer

class socketserver.ThreadingTCPServer

class socketserver.ThreadingUDPServer

ForkingTCPServer 多进程（效果与多线程一样）。（在windows上不能执行，没有fork）

socketserver.BaseServer(server_address, RequestHandlerClass) 主要有以下方法：1.fileno() 返回文件描述符（一般用不到）2.handle_request() 处理单个请求

3.serve_forever(poll_interval=0.5) 每0.5秒检测一下是否有shutdown信号 4.service_actions() 5.shutdown() 6.server_close() 7.address_family 8.RequestHandlerClass 9.server_address 10.socket 11.allow_reuse_address 12.request_queue_size 13.socket_type 14.timeout 15.finish_request()（self.setup(),self.handle(),self.finish()）16.get_request() 17.handle_error(request, client_address) 18.handle_timeout() 19.process_request(request, client_address) 20.server_activate() 21.server_bind() 22.verify_request(request, client_address)

作业：开发一个支持多用户在线的FTP程序

要求：

用户加密认证
允许同时多用户登录
每个用户有自己的家目录，且只能访问自己的家目录
对用户进行磁盘配额，每个用户的可用空间不同
允许用户在ftp server上随意切换目录
允许用户查看当前目录下文件
允许上传和下载文件，保证文件一致性
文件传输过程中显示进度条
附加功能：支持文件的断点续传

服务器端：

 import socketserver

 import json,os

 class MyTCPHandler(socketserver.BaseRequestHandler):

     def put(self,*args):

         '''接受客户端文件'''

         cmd_dic=args[0]

         filename=cmd_dic["filename"]

         file_size=cmd_dic["size"]

         if os.path.isfile(filename):

             f=open(filename+".new","wb")

         else:

             f=open(filename,"wb")

         self.request.send(b"200 ok") #返回客户端请求

         receive_size=0

         while receive_size<file_size:

             data=self.request.recv(1024)

             f.write(data)

             receive_size+=len(data)

         else:

             print("file [%s] has uploaded..."%filename)

     def handle(self):

         while True:

             try:

                 self.data = self.request.recv(1024).strip() #每一个客户端的请求过来都会实例化MyTCPHandler

                 print("{} wrote:".format(self.client_address[0]))

                 print(self.data)

                 cmd_dic=json.loads(self.data.decode())

                 action=cmd_dic["action"]

                 if hasattr(self,action):

                     func=getattr(self,action)

                     func(cmd_dic)

                 self.request.send(self.data.upper())

             except ConnectionResetError as e:

                 print("err:",e)

                 break

 if __name__ == "__main__":

     HOST, PORT = "localhost", 9999

     server = socketserver.ThreadingTCPServer((HOST, PORT), MyTCPHandler) #把ip地址和类当做参数传给TCPServer,TCPServer就开始监听

     server.serve_forever()

客户端：

 import socket

 import json

 import os

 class Ftpclient(object):

     def __init__(self):

         self.client = socket.socket()

     def help(self):

         msg='''

         ls

         pwd

         cd../..

         get filename

         put filename'''

         print(msg)

     def connect(self,ip,port):

         self.client.connect((ip, port))

     def interactive(self):

         #self.authenticate() #用户登录

         while True:

             cmd=input(">>:")

             if len(cmd)==0:continue

             cmd_str=cmd.split()[0]#第一个值是指令

             if hasattr(self,"cmd_%s"%cmd_str):

                 func=getattr(self,"cmd_%s"%cmd_str)

                 func(cmd)

             else:

                 self.help()

     def cmd_put(self,*args):

         cmd_split=args[0].split()

         if len(cmd_split) > 1:

             filename=cmd_split[1]

             if os.path.isfile(filename):

                 file_size=os.stat(filename).st_size

                 # msg_str="%s|%s"%(filename,file_size) #写死了，要考虑长远

                 msg_dic={

                     "action":"put",

                     "filename":filename,

                     "size":file_size,

                     "overriden":True

                 }

                 self.client.send(json.dumps(msg_dic).encode("utf-8"))

                 print("send",json.dumps(msg_dic).encode("utf-8"))

                 #防止粘包，等服务器确认

                 server_response=self.client.recv(1024)

                 f=open(filename,"rb")

                 for line in f:

                     self.client.send(line)

                 else:

                     print("file upload success...")

                     f.close()

             else:

                 print(filename,"is not exist")

     def cmd_get(self):

         pass

 ftp=Ftpclient()

 ftp.connect("localhost",9999)

 ftp.interactive()

巴特西

python学习笔记_week8

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