SocketServer 中非常重要的兩個基類就是：BaseServer 和 BaseRequestHandler
在SocketServer 中也提供了對TCP以及UDP的高級封裝，這次我們主要通過分析關于TCP的處理邏輯來對SocketServer模塊進行一個很好的理解和學習

TCPServer

TCPServer 繼承了BaseServer，初始化的時候，進行了socket套接字的創建。

def __init__(self, server_address, RequestHandlerClass, bind_and_activate=True):"""Constructor. May be extended, do not override."""BaseServer.__init__(self, server_address, RequestHandlerClass)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

在這里我們看到了我們非常熟悉的關于socket的創建的內容：
self.socket = socket.socket(self.address_family, self.socket_type)
通過socket模塊創建了socket對象，接著調用了server_bind和server_activate

server_bind

源碼內容如下：

def server_bind(self):"""Called by constructor to bind the socket.May be overridden."""if self.allow_reuse_address:self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)self.socket.bind(self.server_address)self.server_address = self.socket.getsockname()

這里我們看到了非常熟悉的操作socket.bind方法，以及設置了socket的相關屬性

server_activate

源碼內容如下：

def server_activate(self):"""Called by constructor to activate the server.May be overridden."""self.socket.listen(self.request_queue_size)

同樣的這里的調用也非常簡單就是執行了socket.listen

get_request

在TCPServer類中我們還看到了get_request方法，源碼內容如下：

def get_request(self):"""Get the request and client address from the socket.May be overridden."""return self.socket.accept()

這個的調用其實我們可以在BaseServer這個基類中看到，我們之前看過關于BaseServer中這個基類的源碼
我們可以從我們調用BaseServer基類中的serve_forever方法查看，這里是調用了_handle_request_noblock方法，我繼續查看_handle_request_noblock這個源碼

def _handle_request_noblock(self):"""Handle one request, without blocking.I assume that selector.select() has returned that the socket isreadable before this function was called, so there should be no risk ofblocking in get_request()."""try:request, client_address = self.get_request()except OSError:returnif self.verify_request(request, client_address):try:self.process_request(request, client_address)except:self.handle_error(request, client_address)self.shutdown_request(request)else:self.shutdown_request(request)

可以看到這里最后是調用了process_request來處理請求，繼續查看源碼：

def process_request(self, request, client_address):"""Call finish_request.Overridden by ForkingMixIn and ThreadingMixIn."""self.finish_request(request, client_address)self.shutdown_request(request)def finish_request(self, request, client_address):"""Finish one request by instantiating RequestHandlerClass."""self.RequestHandlerClass(request, client_address, self)

從上面的代碼我們可以到最后是在finish_request中實例化了RequestHandlerClass
我們 這個時候查看一下BaseRequestHandler這個基類的源碼如下:

class BaseRequestHandler:"""Base class for request handler classes.This class is instantiated for each request to be handled. Theconstructor sets the instance variables request, client_addressand server, and then calls the handle() method. To implement aspecific service, all you need to do is to derive a class whichdefines a handle() method.The handle() method can find the request as self.request, theclient address as self.client_address, and the server (in case itneeds access to per-server information) as self.server. Since aseparate instance is created for each request, the handle() methodcan define other arbitrary instance variables."""def __init__(self, request, client_address, server):self.request = requestself.client_address = client_addressself.server = serverself.setup()try:self.handle()finally:self.finish()def setup(self):passdef handle(self):passdef finish(self):pass

在初始化函數里我們看到了調用setup()方法，這setup在StreamRequestHandler會被重寫

StreamRequestHandler

TCPServer實現了使用tcp套接字的網絡服務，Handler方面則是對應的StreamRequestHandler。它繼承了BaseRequestHandler。基類的setup方法和finish方法被它重寫，用于通過連接實現緩存文件的讀寫操作。

setup方法

源碼內容如下：

def setup(self):self.connection = self.requestif self.timeout is not None:self.connection.settimeout(self.timeout)if self.disable_nagle_algorithm:self.connection.setsockopt(socket.IPPROTO_TCP,socket.TCP_NODELAY, True)self.rfile = self.connection.makefile('rb', self.rbufsize)self.wfile = self.connection.makefile('wb', self.wbufsize)

這里主要設置了對應連接的屬性，其中創建了兩個對象非常重要:
一個可讀（rfile）和一個可寫（wfile）的“文件”對象
但是實際并不是創建了文件，而是封裝了讀取數據和發送數據的操作，抽象成了對文件的操作
可以理解：
self.rfile 就是讀取客戶端數據的對象，它有一些方法可以讀取數據。self.wfile則是用來發送數據給客戶端的對象。

整理流程(TCP)

實現TCP服務需要使用TCPServer和StreamRequestHandler共同協作

?

轉載于:https://www.cnblogs.com/zhaof/p/8890600.html

總結

以上是生活随笔為你收集整理的SocketServer源码学习(二)的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。