Python：网络编程：SocketServer

目录

SocketServer

类的继承关系

编程接口

测试代码

 总结&＃xff1a;

实现EchoSerer

练习---改写ChatServer

总结

SocketServer

socket编程过于底层&＃xff0c;编程虽然有套路&＃xff0c;但是想要写出健壮的代码还是比较困难的&＃xff0c;所以很多语言都对socket底层 API进行了封装&＃xff0c;Python的封装就是------socketserver模块&＃xff0c;它是网络服务编程模块&＃xff0c;便于企业级快速开发

类的继承关系

SocketServer简化了网络服务器的编写

它有4个同步类&＃xff1a;TCPServer、UDPServer、UnixStramServer、UnixDatagramServer

2个Mixin类&＃xff1a;ForkingMixin和ThreadingMixin&＃xff0c;用来支持异步

Class ForkingUDPServer(ForkingMixin&＃xff0c;UDPServer):pass        #UDPServer 多进程同异步编程

Class ForkingTCPServer(ForkingMixin&＃xff0c;TCPServer):pass        #TCPServer多线程&＃xff0c;同异步编程

Class  ThreadingUDPServer(ThreadingMixin&＃xff0c;UDPServer):pass        #UDPServer 多线程、同异步编程

Class ThreadingTCPSever(ThreadingMixin&＃xff0c;TCPServer):pass        #TCPServer 多线程编程

fork是创建多进程&＃xff0c;thread是创建多进程

编程接口

socketserver.BaseServer(server_address, RequestHandlerClass) #需要提供服务器绑定的地址信息&＃xff0c;和用于处理请求的RequestHandlerClass类


RequestHandlerClass类必须是BaseRequestHandler类的子类&＃xff0c;在BaseServer中代码如下

class BaseServver:def __init__(self, server_address, RequestHandlerClass):"""Constructor. May be extended, do not override."""self.server_address &＃61; server_addressself.RequestHandlerClass &＃61; RequestHandlerClassself.__is_shut_down &＃61; threading.Event()self.__shutdown_request &＃61; Falsedef finish_request(self, request, client_address): #处理请求的方法"""Finish one request by instantiating RequestHandlerClass."""self.RequestHandlerClass(request, client_address, self)

BaseRequestHandler类

它是和用户连接的用户请求处理类的基类&＃xff0c;定义为BaseRequestHandler(request,client_adress,server)

服务端Server实例接受用户请求后&＃xff0c;最后会实例化这个类
它被初始化后&＃xff0c;送入3个参数&＃xff1a;request、client_address、server自身
以后 就可以在BaseRequestHandler类的实例上使用以下属性&＃xff1a;
self.request是和客户端的连接的socket对象
self.server是TCPServer本身
self.client_address是客户端地址

这个类在初始化的时候&＃xff0c;他会依次调用3个方法。子类可以覆盖这些方法

#BaseRequestHandler要子类覆盖的方法
class BaseRequestHandler:def __init__(self, request, client_address, server):self.request &＃61; requestself.client_address &＃61; client_addressself.server &＃61; serverself.setup()try:self.handle()finally:self.finish()def setup(self): #初始化每一个连接passdef handle(self): #每一次请求处理passdef finish(self): #每一次连接清理pass

测试代码
 

import threading
import socketserver
import loggingFORMAT &＃61; "%(asctime)s %(threadName)s %(thread)d %(message)s"
logging.basicConfig(format&＃61;FORMAT,level&＃61;logging.INFO)class MyHandler_my(socketserver.BaseRequestHandler):def setup(self):super().setup()self.event &＃61; threading.Event()def handle(self):#super().hanler() #可以不调用&＃xff0c;父类handler什么都没走print("~"*30)print(self.server) #服务print(self.request) #服务端负责客户端连接请求的socker对象print(self.client_address) #客户端地址print(self.__dict__)print(self.server.__dict__) #能看到负责accept的socketprint(threading.enumerate())print(threading.current_thread())print("~"*30)# logging.info()while not self.event.is_set():print("come")data &＃61; self.request.recv(1024)msg &＃61; "I&＃96;m comming you msg {} ".format(data.decode())self.request.send(msg.encode())addr&＃61;("127.0.0.1",12000)
server &＃61; socketserver.ThreadingTCPServer(addr,MyHandler_my)
print(server)
logging.info(11)
server.serve_forever() #永久
server.server_close()结果&＃xff1a;
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


(&＃39;127.0.0.1&＃39;, 51527)
{&＃39;request&＃39;: , &＃39;client_address&＃39;: (&＃39;127.0.0.1&＃39;, 51527), &＃39;server&＃39;: , &＃39;event&＃39;: }
{&＃39;server_address&＃39;: (&＃39;127.0.0.1&＃39;, 12000), &＃39;RequestHandlerClass&＃39;: , &＃39;_BaseServer__is_shut_down&＃39;: , &＃39;_BaseServer__shutdown_request&＃39;: False, &＃39;socket&＃39;: , &＃39;_threads&＃39;: []}
[<_MainThread(MainThread, started 24636)>, ]

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
come
come

 总结&＃xff1a;

将ThreadingTCPServer换成TCPServer&＃xff0c;同时连接2个客户端观察效果
ThreadingTCPServer是异步的&＃xff0c;可以同时处理多个连接

TCPServer是同步的&＃xff0c;一个连接处理完了&＃xff0c;即一个连接的handle方法执行完了&＃xff0c;才能处理另一个连接&＃xff0c;且只有主线程

创建服务器需要几个步骤&＃xff1a;

• 从BaseRequestHandler类的派生子类&＃xff0c;并覆盖器handle()方法创建处理程序类&＃xff0c;次方法将处理传入请求
• 实例化一个服务器类&＃xff0c;传参服务器的地址和请求处理类
• 调用服务器实例的handle_request()或server_forever()方法
• 调用server_close() 关闭套接字

实现EchoSerer

import threading
from socketserver import ThreadingTCPServer , BaseRequestHandler
import sysclass EchoHandler(BaseRequestHandler):def setup(self) -> None:super().setup()self.event &＃61; threading.Event() #初始话工作def finish(self) -> None:super().finish()self.event.set()def handle(self) -> None:super().handle()while not self.event.is_set():data &＃61; self.request.recv(1024).decode()msg &＃61; "{} {}".format(self.client_address,data).encode()self.request.send(msg)print("end")addr &＃61; ("127.0.0.1",9999)
server &＃61; ThreadingTCPServer(addr,EchoHandler)
server_thread&＃61; threading.Thread(target&＃61;server.serve_forever,name&＃61;"EchoHandle")
server_thread.start()try:while True:cmd &＃61; input(">>>")if cmd.strip() &＃61;&＃61; "quit":breakprint(threading.enumerate())
except Exception as e:print(e)
except KeyboardInterrupt:pass
finally:print("exit")sys.exit(0)

练习---改写ChatServer

使用ThreadingTCP改写ChatSserver

import threading
from socketserver import ThreadingTCPServer,BaseRequestHandler
import sys
import loggingFORMAT &＃61; &＃39;%(asctime)s %(threadName)s %(thread)d %(message)s&＃39;
logging.basicConfig(format&＃61;FORMAT,level&＃61;logging.INFO)class ChatHandler(BaseRequestHandler):clients &＃61; { }def setup(self) -> None:super().setup()self.event &＃61; threading.Event()self.clients[self.client_address] &＃61; self.requestdef finish(self) -> None:super().finish() #清理工作self.clients.pop(self.client_address) #能执行到吗&＃xff1f;self.event.set()def handle(self) -> None:super().handle()while not self.event.is_set():data &＃61; self.request.recv(1024).decode()if data &＃61;&＃61; "quit":breakmsg &＃61; "{} {} ".format(self.client_address,data).encode()logging.info(msg)for c in self.clients.values():self.request.send(msg)print("End")addr &＃61; ("0.0.0.0",9999)
server_tcp &＃61; ThreadingTCPServer(addr,ChatHandler)server_thread &＃61; threading.Thread(target&＃61;server_tcp.serve_forever,name&＃61;"ChatSever",daemon&＃61;True)
server_thread.start()try:while True:cmd &＃61; input(">>>")if cmd.strip() &＃61;&＃61; &＃39;quit&＃39;:break
except Exception as e:print(e)
except KeyboardInterrupt:pass
finally:print("Exit")sys.exit()结果&＃xff1a;
>>>2021-07-17 10:47:09,845 Thread-1 8912 b"(&＃39;127.0.0.1&＃39;, 50991) 11111 "
End
2021-07-17 10:47:30,923 Thread-2 15940 b"(&＃39;127.0.0.1&＃39;, 50992) fsfs "

上述问题
上例 self.clients.pop(self.client_address)能执行到吗&＃xff1f;如果连接的线程中handler方法抛出异常&＃xff0c;例如客户端主动断开导致的异常&＃xff0c;线程崩溃&＃xff0c;self.clents的pop方法还能执行吗&＃xff1f;

可以执行&＃xff0c;基类源保证了即使异常&＃xff0c;也能执行finish的方法&＃xff0c;但不代表不应该不捕获客户端各种异常

修改客户端断开后的异常

• 通过打印可以看到&＃xff0c;客户端主动断开&＃xff0c;会导致recv方法立即返回一个空bytes&＃xff0c;并没有同时抛出异常&＃xff0c;当循环回到recv这一句的时候就会产生异常&＃xff0c;可以通过判断data数据是否为空来判断客户端是否断开

import threading
from socketserver import ThreadingTCPServer,BaseRequestHandler
import sys
import loggingFORMAT &＃61; &＃39;%(asctime)s %(threadName)s %(thread)d %(message)s&＃39;
logging.basicConfig(format&＃61;FORMAT,level&＃61;logging.INFO)class ChatHandler(BaseRequestHandler):clients &＃61; { }def setup(self) -> None:super().setup()self.event &＃61; threading.Event()self.clients[self.client_address] &＃61; self.requestdef finish(self) -> None:super().finish() #清理工作self.clients.pop(self.client_address)self.event.set()def handle(self) -> None:super().handle()while not self.event.is_set():data &＃61; self.request.recv(1024).decode()print(data,"~"*30)if not data or data &＃61;&＃61; "quit":breakmsg &＃61; "{} {} ".format(self.client_address,data).encode()logging.info(msg)for c in self.clients.values():self.request.send(msg)print("End")addr &＃61; ("0.0.0.0",9999)
server_tcp &＃61; ThreadingTCPServer(addr,ChatHandler)server_thread &＃61; threading.Thread(target&＃61;server_tcp.serve_forever,name&＃61;"ChatSever",daemon&＃61;True)
server_thread.start()try:while True:cmd &＃61; input(">>>")if cmd.strip() &＃61;&＃61; &＃39;quit&＃39;:break
except Exception as e:print(e)
except KeyboardInterrupt:pass
finally:print("Exit")sys.exit()

总结

为每一个连接提供RequestHandlerClass类的实例&＃xff0c;一次调用setup、handle、finish方法&＃xff0c;且使用try……finally结构保证finish方法一定能被调用。这些方法依次执行完成&＃xff0c;如果想维持这个连接和客户端通信&＃xff0c;就需要在handler函数中使用循环

sockerserver模块提供的不同的类&＃xff0c;但是编程接口是一样的&＃xff0c;即使多线程&＃xff0c;多进程的类也是一样&＃xff0c;大大减少了编程的难度