week8

---恢复内容开始---

week8

1、动态导入模块

2、断言

3、ftp

4、socketserver

1、动态导入模块

 import importlib

 a = importlib.import_module('aa.aa') # aa目录下的aa模块

 print(aa.import_C().name)

2、断言

跟if有点类似，判断是否符合条件，是则继续，否则报错。

 a = 'name'

 assert type(a) is str

3、FTP(文件传输：单下载)

 客户端

 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、客户端确认

 7、开始边读边发数据

 8、md5

 import socket,os,hashlib

 server = socket.socket()

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

 server.lisen()

 m = hashlib.md5()

 while True:

     try:

         conn,addr = server.accept()

         data = conn.recv(1024)

         cmd,filename =data.split()

         if os.path.isfile(filename):

             f = open(filename,'rb')

             filesize = f.stat(filename).st_size

             conn.send(str(filesize).encode())

             conn.recv(1024)

             for line in f:

                 m.update(line)

                 conn.send(line)

                 print(m.hexdigest())

             conn.send(str(hexdigest).encode)

             f.close

         print(send done')

     except ConnectionResetError as e:

         print('连接错误',e)

 server.close()

客户端

 import socket,os,hashlib

 client = socket.socket()

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

 m = hashlib.md5

 while True:

     cmd = imput('>>>:').strip()

     if len(cmd) == 0:continue

     filesize = client.recv(1024)

     client.send('请求发送’) #无实际意义的交互，防止粘包

     filename = cmd.split[1]

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

     rec_filesize = 0

     filesize = int(filesize.decode())

     while filesize > rec_filesize:

         if filesize - rec_filesize > 1024: # 做判断防止最后一次接收出现粘包

             res_size = 1024

         else:

             res_size = filesize - rec_filesize

         data = client.recv(res_size)

         f.write(data)

         rec_filesize += len(data)

         m.update(data)

     else:

         new_file_md5 = m.hexdigest()

         print('new file md5:',new_file_md5)

     server_file_md5 = client.recv(1024)

     print('server file md5',server_file_md5) #接收服务端读取的md5，与自己生成的md5进行比较

 client.close

服务端

4、socketserver(面向对象的方法进行文件传输)

创建方式:

创建一个socketserver 至少分以下几步:

First, you must create a request handler class by subclassing the BaseRequestHandlerclass and overriding its handle() method; this method will process incoming requests. 　　
Second, you must instantiate one of the server classes, passing it the server’s address and the request handler class.
Then call the handle_request() orserve_forever() method of the server object to process one or many requests.
Finally, call server_close() to close the socket.

self.setup  请求处理前进行的事项
self.handle 请求处理中的事项
self.finish 请求处理后的事项

 import socketserver

 class MyTCPServer(socketserver.BaseRequestHandler):

     def setup(self): #交互前的动作

         pass

     def handle(self): #与用户的所有交互都在这里进行

         self.data = self.request.recv(1024)

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

         self.request.sendall(self.data.upper)

     def finish(self): #与用户交互后的动作

         pass

 if  __name__ == '__main__'

     HOST , PORT = 'localhost',9999

     server = socketserver.ThreadingTCPServer((HOST,PORT),MyTCPServer)

 #ThreadingTCPServer 多线程

 #ForingTCPServer 多进程 在win不好使

 server.server_forever()

客户端