基于python select.select模塊通信的實(shí)例講解

要理解select.select模塊其實(shí)主要就是要理解它的參數(shù), 以及其三個(gè)返回值。
select()方法接收并監(jiān)控3個(gè)通信列表， 第一個(gè)是所有的輸入的data,就是指外部發(fā)過(guò)來(lái)的數(shù)據(jù)，第2個(gè)是監(jiān)控和接收所有要發(fā)出去的data(outgoing data),第3個(gè)監(jiān)控錯(cuò)誤信息在網(wǎng)上一直在找這個(gè)select.select的參數(shù)解釋, 但實(shí)在是沒(méi)有, 哎...自己硬著頭皮分析了一下。    
readable, writable, exceptional = select.select(inputs, outputs, inputs)
第一個(gè)參數(shù)就是服務(wù)器端的socket, 第二個(gè)是我們?cè)谶\(yùn)行過(guò)程中存儲(chǔ)的客戶端的socket, 第三個(gè)存儲(chǔ)錯(cuò)誤信息。
重點(diǎn)是在返回值, 第一個(gè)返回的是可讀的list, 第二個(gè)存儲(chǔ)的是可寫(xiě)的list, 第三個(gè)存儲(chǔ)的是錯(cuò)誤信息的list。
這個(gè)也不必深究, 看看代碼自己分析下就能有大概理解。
網(wǎng)上所有關(guān)于select.select的代碼都是差不多的, 但是有些不能運(yùn)行, 或是不全。我自己重新寫(xiě)了一份能運(yùn)行的程序, 做了很多注釋, 好好看看就能搞懂
服務(wù)器端：    
# coding: utf-8
import select
import socket
import Queue
from time import sleep
 
 
# Create a TCP/IP
server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server.setblocking(False)
 
# Bind the socket to the port
server_address = ('localhost', 8090)
print ('starting up on %s port %s' % server_address)
server.bind(server_address)
 
# Listen for incoming connections
server.listen(5)
 
# Sockets from which we expect to read
inputs = [server]
 
# Sockets to which we expect to write
# 處理要發(fā)送的消息
outputs = []
 
# Outgoing message queues (socket: Queue)
message_queues = {}
 
while inputs:
  # Wait for at least one of the sockets to be ready for processing
  print ('waiting for the next event')
  # 開(kāi)始select 監(jiān)聽(tīng), 對(duì)input_list 中的服務(wù)器端server 進(jìn)行監(jiān)聽(tīng)
  # 一旦調(diào)用socket的send, recv函數(shù)，將會(huì)再次調(diào)用此模塊
  readable, writable, exceptional = select.select(inputs, outputs, inputs)
 
  # Handle inputs
  # 循環(huán)判斷是否有客戶端連接進(jìn)來(lái), 當(dāng)有客戶端連接進(jìn)來(lái)時(shí)select 將觸發(fā)
  for s in readable:
    # 判斷當(dāng)前觸發(fā)的是不是服務(wù)端對(duì)象, 當(dāng)觸發(fā)的對(duì)象是服務(wù)端對(duì)象時(shí),說(shuō)明有新客戶端連接進(jìn)來(lái)了
    # 表示有新用戶來(lái)連接
    if s is server:
      # A "readable" socket is ready to accept a connection
      connection, client_address = s.accept()
      print ('connection from', client_address)
      # this is connection not server
      connection.setblocking(0)
      # 將客戶端對(duì)象也加入到監(jiān)聽(tīng)的列表中, 當(dāng)客戶端發(fā)送消息時(shí) select 將觸發(fā)
      inputs.append(connection)
 
      # Give the connection a queue for data we want to send
      # 為連接的客戶端單獨(dú)創(chuàng)建一個(gè)消息隊(duì)列，用來(lái)保存客戶端發(fā)送的消息
      message_queues[connection] = Queue.Queue()
    else:
      # 有老用戶發(fā)消息, 處理接受
      # 由于客戶端連接進(jìn)來(lái)時(shí)服務(wù)端接收客戶端連接請(qǐng)求，將客戶端加入到了監(jiān)聽(tīng)列表中(input_list), 客戶端發(fā)送消息將觸發(fā)
      # 所以判斷是否是客戶端對(duì)象觸發(fā)
      data = s.recv(1024)
      # 客戶端未斷開(kāi)
      if data != '':
        # A readable client socket has data
        print ('received "%s" from %s' % (data, s.getpeername()))
        # 將收到的消息放入到相對(duì)應(yīng)的socket客戶端的消息隊(duì)列中
        message_queues[s].put(data)
        # Add output channel for response
        # 將需要進(jìn)行回復(fù)操作socket放到output 列表中, 讓select監(jiān)聽(tīng)
        if s not in outputs:
          outputs.append(s)
      else:
        # 客戶端斷開(kāi)了連接, 將客戶端的監(jiān)聽(tīng)從input列表中移除
        # Interpret empty result as closed connection
        print ('closing', client_address)
        # Stop listening for input on the connection
        if s in outputs:
          outputs.remove(s)
        inputs.remove(s)
        s.close()
 
        # Remove message queue
        # 移除對(duì)應(yīng)socket客戶端對(duì)象的消息隊(duì)列
        del message_queues[s]
 
  # Handle outputs
  # 如果現(xiàn)在沒(méi)有客戶端請(qǐng)求, 也沒(méi)有客戶端發(fā)送消息時(shí), 開(kāi)始對(duì)發(fā)送消息列表進(jìn)行處理, 是否需要發(fā)送消息
  # 存儲(chǔ)哪個(gè)客戶端發(fā)送過(guò)消息
  for s in writable:
    try:
      # 如果消息隊(duì)列中有消息,從消息隊(duì)列中獲取要發(fā)送的消息
      message_queue = message_queues.get(s)
      send_data = ''
      if message_queue is not None:
        send_data = message_queue.get_nowait()
      else:
        # 客戶端連接斷開(kāi)了
        print "has closed "
    except Queue.Empty:
      # 客戶端連接斷開(kāi)了
      print "%s" % (s.getpeername())
      outputs.remove(s)
    else:
      # print "sending %s to %s " % (send_data, s.getpeername)
      # print "send something"
      if message_queue is not None:
        s.send(send_data)
      else:
        print "has closed "
      # del message_queues[s]
      # writable.remove(s)
      # print "Client %s disconnected" % (client_address)
 
  # # Handle "exceptional conditions"
  # 處理異常的情況
  for s in exceptional:
    print ('exception condition on', s.getpeername())
    # Stop listening for input on the connection
    inputs.remove(s)
    if s in outputs:
      outputs.remove(s)
    s.close()
 
    # Remove message queue
    del message_queues[s]
 
  sleep(1)

客戶端：    
# coding: utf-8
import socket
 
 
messages = ['This is the message ', 'It will be sent ', 'in parts ', ]
 
server_address = ('localhost', 8090)
 
# Create aTCP/IP socket
 
socks = [socket.socket(socket.AF_INET, socket.SOCK_STREAM), socket.socket(socket.AF_INET, socket.SOCK_STREAM), ]
 
# Connect thesocket to the port where the server is listening
 
print ('connecting to %s port %s' % server_address)
# 連接到服務(wù)器
for s in socks:
  s.connect(server_address)
 
for index, message in enumerate(messages):
  # Send messages on both sockets
  for s in socks:
    print ('%s: sending "%s"' % (s.getsockname(), message + str(index)))
    s.send(bytes(message + str(index)).decode('utf-8'))
  # Read responses on both sockets
 
for s in socks:
  data = s.recv(1024)
  print ('%s: received "%s"' % (s.getsockname(), data))
  if data != "":
    print ('closingsocket', s.getsockname())
    s.close()
寫(xiě)代碼過(guò)程中遇到了兩個(gè)問(wèn)題, 一是如何判斷客戶端已經(jīng)關(guān)閉了socket連接, 后來(lái)自己分析了下, 如果關(guān)閉了客戶端socket, 那么此時(shí)服務(wù)器端接收到的data就是'', 加個(gè)這個(gè)判斷。二是如果服務(wù)器端關(guān)閉了socket, 一旦在調(diào)用socket的相關(guān)方法都會(huì)報(bào)錯(cuò), 不管socket是不是用不同的容器存儲(chǔ)的(意思是說(shuō)list_1存儲(chǔ)了socket1, list_2存儲(chǔ)了socket1, 我關(guān)閉了socket1, 兩者都不能在調(diào)用這個(gè)socket了)
服務(wù)器端：

客戶端：

以上這篇基于python select.select模塊通信的實(shí)例講解就是小編分享給大家的全部?jī)?nèi)容了