week8

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week8

1、动态导入模块

2、断言

3、ftp

4、socketserver

1、动态导入模块

1 import importlib
2 a = importlib.import_module('aa.aa') # aa目录下的aa模块
3 print(aa.import_C().name)

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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。

1 a = 'name'
2 assert type(a) is str

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3、FTP(文件传输：单下载)

 1 客户端
 2 1、读取文件名
 3 2、检测文件是否存在
 4 3、打开文件
 5 4、检测文件大小
 6 5、发送文件大小给客户端
 7 6、客户端确认
 8 7、开始边读边发数据
 9 8、md5
10 
11 import socket,os,hashlib
12 server = socket.socket()
13 server.bind(('localhost',9999))
14 server.lisen()
15 m = hashlib.md5()
16 while True:
17     try:
18         conn,addr = server.accept() 
19         data = conn.recv(1024)
20         cmd,filename =data.split()
21         if os.path.isfile(filename):
22             f = open(filename,'rb')
23             filesize = f.stat(filename).st_size
24             conn.send(str(filesize).encode())
25             conn.recv(1024)
26             for line in f:
27                 m.update(line)
28                 conn.send(line)
29                 print(m.hexdigest())
30             conn.send(str(hexdigest).encode)
31             f.close
32         print(send done')
33     except ConnectionResetError as e:
34         print('连接错误',e)
35 server.close()

客户端

 1 import socket,os,hashlib
 2 client = socket.socket()
 3 client.connect(('localhost',9999))
 4 m = hashlib.md5
 5 while True:
 6     cmd = imput('>>>:').strip()
 7     if len(cmd) == 0:continue
 8     filesize = client.recv(1024)
 9     client.send('请求发送’) #无实际意义的交互，防止粘包
10     filename = cmd.split[1]
11     f = open(filename+'.new','wb')
12     rec_filesize = 0
13     filesize = int(filesize.decode())
14     while filesize > rec_filesize:
15         if filesize - rec_filesize > 1024: # 做判断防止最后一次接收出现粘包
16             res_size = 1024
17         else:
18             res_size = filesize - rec_filesize
19         data = client.recv(res_size)
20         f.write(data)
21         rec_filesize += len(data)
22         m.update(data)
23     else:
24         new_file_md5 = m.hexdigest()
25         print('new file md5:',new_file_md5)
26     server_file_md5 = client.recv(1024)
27     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
28 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

 1 import socketserver
 2 
 3 class MyTCPServer(socketserver.BaseRequestHandler):
 4     def setup(self): #交互前的动作
 5         pass
 6     def handle(self): #与用户的所有交互都在这里进行
 7         self.data = self.request.recv(1024)
 8         print("{} wrote:".format(self.client_address[0]))
 9         self.request.sendall(self.data.upper)
10     def finish(self): #与用户交互后的动作
11         pass
12 
13 
14 if  __name__ == '__main__'
15     HOST , PORT = 'localhost',9999
16     server = socketserver.ThreadingTCPServer((HOST,PORT),MyTCPServer)
17 #ThreadingTCPServer 多线程
18 #ForingTCPServer 多进程 在win不好使
19 server.server_forever()

客户端