socket編程步驟
服務端創建一個socket，綁定地址和端口，然後監聽端口上傳入的連接,一旦有連接進來，就通過accept函數接收傳入的連接。
客戶端也是創建一個socket。綁定遠端位址和端口，然後建立連接，發送資料。
服務端socket
下面透過一段實例程式碼來詳細說明 服務端 socker_server.py
import socket
import sys
HOST = "127.0.0.1"
PORT = 10000
s = None
for res in socket.getaddrinfo(HOST, PORT, socket.AF_UNSPEC,
socket.SOCK_STREAM, 0, socket.AI_PASSIVE):
af, socktype, proto, canonname, sa = res
try:
s = socket.socket(af, socktype, proto)
except socket.error as msg:
s = None
continue
try:
s.bind(sa)
s.listen(5)
except socket.error as msg:
s.close()
s = None
continue
break
if s is None:
print 'could not open socket'
sys.exit(1)
conn, addr = s.accept()
print 'Connected by', addr
while 1:
data = conn.recv(1024)
if not data: break
conn.send(data)
conn.close()首先我們透過socket.getaddrinnfo函數將host/port轉換成一個包含5元組的序列。這個5元組包含我們創建一個socket連接所需的所有必要參數。回傳的5元組分別是 (family, sockettype, proto, canonname, sockaddr)
family 位址簇，用與socket()函數的第一個參數。主要有以下幾個
socket.AF_UNIX 用與單一機器下的進程通信
socket.AF_INET 用與伺服器之間相互通信，通常都用這個。
socket.AF_INET6 支援IPv6
sockettype socket類型，用與socket()函數的第二個參數，常用的有
socket.SOCK_STREAM 默認，用於TCP協定
socket.於socket()函數的第三個參數。 getaddrinnfo函數會根據位址格式和socket類型,傳回適當的協定
s = socket.socket(af, socktype, proto)
s.bind(sa)
s.listen(5)
conn, addr = s.accept()
data = conn.recv(1024) # 接收数据, 这里指定一次最多接收的字符数量为1024 conn.send(data) # 发送数据
for res in socket.getaddrinfo(HOST, PORT, socket.AF_UNSPEC, socket.SOCK_STREAM):
af, socktype, proto, canonname, sa = res
try:
s = socket.socket(af, socktype, proto)
except socket.error as msg:
s = None
continue
try:
s.connect(sa)
except socket.error as msg:
s.close()
s = None
continue
break
if s is None:
print 'could not open socket'
sys.exit(1)
s.sendall('Hello, world')
data = s.recv(1024)
s.close()
print 'Received', repr(data)socket.sendto(string, flags, address) socket.recvfrom(bufsize[, flags]) #返回(string, address)，string是返回的数据，address是发送方的socket地址
UDPServer 建立UDP協定的套接字流
🎜我們有了套接字流對象，還需要一個請求處理類別。 SocketServer模組提供了請求處理類別有BaseRequestHandler，以及它的衍生類別StreamRequestHandler和DatagramRequestHandler。所以只要繼承這3個類別中的一個，然後重寫handle函數，此函數將用來處理接收到的請求。下面看一個服務端的程式碼範例🎜import SocketServer
class MyTCPHandler(SocketServer.StreamRequestHandler):
"""创建请求处理类，重写handle方法。此外也可以重写setup()和finish()来做一些请求处理前和处理后的一些工作"""
def handle(self):
# self.request is the TCP socket connected to the client
self.data = self.request.recv(1024).strip()
print "{} wrote:".format(self.client_address[0])
print self.data
# just send back the same data, but upper-cased
self.request.sendall(self.data.upper())
if __name__ == "__main__":
HOST, PORT = "localhost", 10000
server = SocketServer.TCPServer((HOST, PORT), MyTCPHandler)
# Activate the server; this will keep running until you
# interrupt the program with Ctrl-C
# server.shutdown()
server.serve_forever() # 一直循环接收请求
# server.handle_request() # 只处理一次请求就退出看着是不是代码简单了很多，而且SocketServer模块内部使用了多路复用IO技术，可以实现更好的连接性能。看serve_forever函数的源代码用到了select模块。通过传入socket对象调用select.select()来监听socket对象的文件描述符，一旦发现socket对象就绪，就通知应用程序进行相应的读写操作。源代码如下：
def serve_forever(self, poll_interval=0.5):
"""Handle one request at a time until shutdown.
Polls for shutdown every poll_interval seconds. Ignores
self.timeout. If you need to do periodic tasks, do them in
another thread.
"""
self.__is_shut_down.clear()
try:
while not self.__shutdown_request:
# XXX: Consider using another file descriptor or
# connecting to the socket to wake this up instead of
# polling. Polling reduces our responsiveness to a
# shutdown request and wastes cpu at all other times.
r, w, e = _eintr_retry(select.select, [self], [], [],
poll_interval)
if self in r:
self._handle_request_noblock()
finally:
self.__shutdown_request = False
self.__is_shut_down.set()即使使用了select技术，TCPServer，UDPServer处理请求仍然是同步的，意味着一个请求处理完，才能处理下一个请求。但SocketServer模块提供了另外2个类用来支持异步的模式。
ForkingMixIn 利用多进程实现异步
ThreadingMixIn 利用多线程实现异步
看名字就知道使用了mixin模式。而mixin模式可以通过多继承来实现，所以通过对网络服务类进行多继承的方式就可以实现异步模式
class ThreadedTCPServer(SocketServer.ThreadingMixIn, SocketServer.TCPServer):
pass针对ThreadindMixIn,实现异步的原理也就是在内部对每个请求创建一个线程来处理。看源码
def process_request(self, request, client_address):
"""Start a new thread to process the request."""
t = threading.Thread(target = self.process_request_thread,
args = (request, client_address))
t.daemon = self.daemon_threads
t.start()下面提供一个异步模式的示例
import socket
import threading
import SocketServer
class ThreadedTCPRequestHandler(SocketServer.BaseRequestHandler):
def handle(self):
data = self.request.recv(1024)
cur_thread = threading.current_thread()
response = "{}: {}".format(cur_thread.name, data)
self.request.sendall(response)
class ThreadedTCPServer(SocketServer.ThreadingMixIn, SocketServer.TCPServer):
pass
def client(ip, port, message):
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect((ip, port))
try:
sock.sendall(message)
response = sock.recv(1024)
print "Received: {}".format(response)
finally:
sock.close()
if __name__ == "__main__":
# Port 0 means to select an arbitrary unused port
HOST, PORT = "localhost", 0
server = ThreadedTCPServer((HOST, PORT), ThreadedTCPRequestHandler)
ip, port = server.server_address
# Start a thread with the server -- that thread will then start one
# more thread for each request
server_thread = threading.Thread(target=server.serve_forever)
# Exit the server thread when the main thread terminates
server_thread.daemon = True
server_thread.start()
print "Server loop running in thread:", server_thread.name
client(ip, port, "Hello World 1")
client(ip, port, "Hello World 2")
client(ip, port, "Hello World 3")
server.shutdown()
server.server_close()以上是本人对socket相关的理解，有什么不当或错误之处，还请指出。
