socketserver模块使用方法

一、socketserver模块介绍

Python提供了两个基本的socket模块。一个是socket，它提供了标准的BSD Socket API；另一个是socketserver，它提供了服务器中心类，可以简化网络服务器的开发

socketserver

socketserver内部使用IO多路复用以及“多线程”和“多进程”，从而实现并发处理多个客户端请求的socket服务端。即，每个客服端请求连接到服务器时，socket服务端都会在服务器上创建一个“线程”或“进程”专门负责处理当前客户端的所有请求。

二、socketserver中的ThreadingTCPServer类

ThreadingTCPServer实现的socket服务器内部会为每个client创建一个“线程”，该线程用来和客户端就行交互 ThreadingTCPServer源码内容：

class ThreadingTCPServer(ThreadingMixIn, TCPServer): pass


#可以看到ThreadTCPServer类本身并没有方法，而是继承了(ThreadingMinIn, TCPServer) 这两个类。 而TCPServer则是继承了BaseServer类。

三、ThreadingTCPServer的使用方法

1、创建一个继承socketserver.BaseRequestHandler的类

2、类中必须重写一个名为handler的方法

3、实例化一个服务器类，传入服务器的地址和请求处理程序类

4、调用serve_forever()事件循环监听

#!/usr/bin/env python3
import socketserver

class Handler(socketserver.BaseRequestHandler):    # 必须继承BaseRequestHandler
    def handle(self):        # 必须有handle方法
        print('New connection:',self.client_address)
        while True:
            data = self.request.recv(1024)
            if not data:break
            print('Client data:',data.decode())
            self.request.send(data)

if __name__ == '__main__':
    server = socketserver.ThreadingTCPServer(('127.0.0.1',8009),Handler)    # 实例化对象，实现多线程的socket
    server.serve_forever()    # 事件监听，并调用handler方法

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四、ThreadingTCPServer执行过程

1、启动服务端程序

2、执行TCPServer.__init__方法，创建服务端socket对象并绑定IP和端口（根据类的继承关系，即查找顺序找到TCPServer.__init__())

3、执行BaseServer.__init__方法，将自定义的继承自socketserver.BaseRequestHandler的类MyRequestHandler赋值给self.RequestHandlerClass class TCPServer(BaseServer): #(继承了BaseServeer类)

class TCPServer(BaseServer): #(继承了BaseServeer类)
    def __init__(self, server_address, RequestHandlerClass, bind_and_activate=True):
        """Constructor.  May be extended, do not override."""
        BaseServer.__init__(self, server_address, RequestHandlerClass)  #(重写了BaseServer的__init__方法)
        self.socket = socket.socket(self.address_family,
                                    self.socket_type)
        if bind_and_activate:
            try:
                self.server_bind()
                self.server_activate()
            except:
                self.server_close()
                raise

class BaseServer:
    def __init__(self, server_address, RequestHandlerClass):  #(接收了两个传进来的参数)
        """Constructor.  May be extended, do not override."""
        self.server_address = server_address
        self.RequestHandlerClass = RequestHandlerClass     #(赋值给了self.RequestHandlerClass)
        self.__is_shut_down = threading.Event()
        self.__shutdown_request = False

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4、通过实例化的对象，执行serve_forever方法，该方法首先查找到BaseServer下的方法，通过调用selector模块，注册事件监听对象，并执行_handle_request_noblock方法找到此方法，并调用该方法下的process_request方法，在此调用到finish_request方法，通过finish_request方法，执行了RequestHandlerClass方法，执行此方法就相当于调用了我们重写的Handler类。

class BaseServer:
    def serve_forever(self, poll_interval=0.5):
        try:
            with _ServerSelector() as selector:
                selector.register(self, selectors.EVENT_READ)

                while not self.__shutdown_request:
                    ready = selector.select(poll_interval)
                    if ready:
                        self._handle_request_noblock()

                    self.service_actions()
   def _handle_request_noblock(self):
        try:
            request, client_address = self.get_request()
        except OSError:
            return
        if self.verify_request(request, client_address):
            try:
                self.process_request(request, client_address)
            except Exception:
                self.handle_error(request, client_address)
                self.shutdown_request(request)
            except:
                self.shutdown_request(request)
                raise
        else:
            self.shutdown_request(request)
    def process_request(self, request, client_address):
        self.finish_request(request, client_address)
        self.shutdown_request(request)
    def finish_request(self, request, client_address):
        self.RequestHandlerClass(request, client_address, self)

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5、通过Handler类实例化对象，调用继承的BaseRequestHandler类中的__init__方法，并执行了handler方法。从而运行了我们重写Handler类中的handler方法。

class BaseRequestHandler:
    def __init__(self, request, client_address, server):
        self.request = request
        self.client_address = client_address
        self.server = server
        self.setup()
        try:
            self.handle()   #调用handler()
        finally:
            self.finish()

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五、调用流程图

Python提供了两个基本的socket模块。一个是socket，它提供了标准的BSD Socket API；另一个是socketserver，它提供了服务器中心类，可以简化网络服务器的开发

socketserver

二、socketserver中的ThreadingTCPServer类

ThreadingTCPServer实现的socket服务器内部会为每个client创建一个“线程”，该线程用来和客户端就行交互 ThreadingTCPServer源码内容：

class ThreadingTCPServer(ThreadingMixIn, TCPServer): pass


#可以看到ThreadTCPServer类本身并没有方法，而是继承了(ThreadingMinIn, TCPServer) 这两个类。 而TCPServer则是继承了BaseServer类。

三、ThreadingTCPServer的使用方法

1、创建一个继承socketserver.BaseRequestHandler的类

2、类中必须重写一个名为handler的方法

3、实例化一个服务器类，传入服务器的地址和请求处理程序类

4、调用serve_forever()事件循环监听

#!/usr/bin/env python3
import socketserver

class Handler(socketserver.BaseRequestHandler):    # 必须继承BaseRequestHandler
    def handle(self):        # 必须有handle方法
        print('New connection:',self.client_address)
        while True:
            data = self.request.recv(1024)
            if not data:break
            print('Client data:',data.decode())
            self.request.send(data)

if __name__ == '__main__':
    server = socketserver.ThreadingTCPServer(('127.0.0.1',8009),Handler)    # 实例化对象，实现多线程的socket
    server.serve_forever()    # 事件监听，并调用handler方法

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四、ThreadingTCPServer执行过程

1、启动服务端程序

2、执行TCPServer.__init__方法，创建服务端socket对象并绑定IP和端口（根据类的继承关系，即查找顺序找到TCPServer.__init__())

class TCPServer(BaseServer): #(继承了BaseServeer类)
    def __init__(self, server_address, RequestHandlerClass, bind_and_activate=True):
        """Constructor.  May be extended, do not override."""
        BaseServer.__init__(self, server_address, RequestHandlerClass)  #(重写了BaseServer的__init__方法)
        self.socket = socket.socket(self.address_family,
                                    self.socket_type)
        if bind_and_activate:
            try:
                self.server_bind()
                self.server_activate()
            except:
                self.server_close()
                raise

class BaseServer:
    def __init__(self, server_address, RequestHandlerClass):  #(接收了两个传进来的参数)
        """Constructor.  May be extended, do not override."""
        self.server_address = server_address
        self.RequestHandlerClass = RequestHandlerClass     #(赋值给了self.RequestHandlerClass)
        self.__is_shut_down = threading.Event()
        self.__shutdown_request = False

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class BaseServer:
    def serve_forever(self, poll_interval=0.5):
        try:
            with _ServerSelector() as selector:
                selector.register(self, selectors.EVENT_READ)

                while not self.__shutdown_request:
                    ready = selector.select(poll_interval)
                    if ready:
                        self._handle_request_noblock()

                    self.service_actions()
   def _handle_request_noblock(self):
        try:
            request, client_address = self.get_request()
        except OSError:
            return
        if self.verify_request(request, client_address):
            try:
                self.process_request(request, client_address)
            except Exception:
                self.handle_error(request, client_address)
                self.shutdown_request(request)
            except:
                self.shutdown_request(request)
                raise
        else:
            self.shutdown_request(request)
    def process_request(self, request, client_address):
        self.finish_request(request, client_address)
        self.shutdown_request(request)
    def finish_request(self, request, client_address):
        self.RequestHandlerClass(request, client_address, self)

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5、通过Handler类实例化对象，调用继承的BaseRequestHandler类中的__init__方法，并执行了handler方法。从而运行了我们重写Handler类中的handler方法。

class BaseRequestHandler:
    def __init__(self, request, client_address, server):
        self.request = request
        self.client_address = client_address
        self.server = server
        self.setup()
        try:
            self.handle()   #调用handler()
        finally:
            self.finish()

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