python 網(wǎng)絡(luò)編程要點(diǎn)總結(jié)
應(yīng)表會(huì)傳網(wǎng)數(shù)物:
應(yīng)用層、表示層、會(huì)話層: (這三層又可以合并為應(yīng)用層,這樣就是五層網(wǎng)絡(luò)協(xié)議【osi五層協(xié)議】) python ’你好’.encoding(’utf-8’)
傳輸層: 預(yù)備如何傳輸、使用的端口 (port,tcp,udp); 四層路由器、四層交換機(jī)
網(wǎng)絡(luò)層: ip(ipv4 ipv6); 路由器、三層交換機(jī)
數(shù)據(jù)鏈路層: mac(mac, arp協(xié)議:可以通過ip找到mac); 二層交換機(jī)、網(wǎng)卡(單播、廣播、組播,arp用到單播和廣播)
物理層 : 轉(zhuǎn)成電信號(hào)
2,TCP/UDPtcp需要先建立連接,然后才能夠通信(類似于打電話)
占用連接,可靠(消息不會(huì)丟失),實(shí)時(shí)性高,慢(效率低、面向連接、可靠、全雙工) 三次握手 客戶端向服務(wù)器端發(fā)送syn請(qǐng)求服務(wù)端回復(fù)ack并發(fā)送syn請(qǐng)求客戶端接收到請(qǐng)求后再回復(fù)ack,連接建立 在socket中是由 客戶端connect() 和 服務(wù)端accept()兩個(gè)命令完成的 四次揮手 客戶端向服務(wù)端發(fā)送fin請(qǐng)求服務(wù)端回復(fù)ack確認(rèn)服務(wù)端向客戶端發(fā)送fin請(qǐng)求客戶端回復(fù)ack確認(rèn) 在socket中是由 客戶端sk.close() 和 服務(wù)端 conn.close()兩個(gè)命令完成的 揮手時(shí)服務(wù)端的ack和fin不能同時(shí)發(fā)送,因?yàn)榭蛻舳税l(fā)送完所有信息時(shí),服務(wù)端不一定完成了所有信息的發(fā)送udp不需要建立連接,就可以通信(類似于發(fā)信息)
不占用連接,不夠可靠(消息因?yàn)榫W(wǎng)絡(luò)不穩(wěn)定可能丟失),實(shí)時(shí)性不高(效率高、無連接的、不可靠的)
3,例子’’’------------------------------TCP協(xié)議------------------------------’’’’’’server’’’import socketsk = socket.socket()sk.bind((’127.0.0.1’, 6000))sk.listen()conn, addr = sk.accept()conn.send(’你好’.encode(’utf-8’))msg = conn.recv(1024)print(msg.decode(’utf-8’))conn.close()sk.close()’’’client’’’import socketsk = socket.socket()sk.connect((’127.0.0.1’, 6000))msg = sk.recv(1024)print(msg.decode(’utf-8’))sk.send(’再見’.encode(’utf-8’))sk.close()’’’------------------------------UDP協(xié)議------------------------------’’’’’’server’’’import socketsk = socket.socket(type=socket.SOCK_DGRAM) #SOCK_DGRAM udp default tcpsk.bind((’127.0.0.1’, 6000))# msg = sk.recv(1024)# print(msg.decode(’utf-8’))while True: msg = sk.recvfrom(1024) print(msg) print(msg[0].decode(’utf-8’)) if msg[0].decode(’utf-8’) == ’對(duì)方和你斷開了連接’:continue msgSend = input(’>>>’) sk.sendto(msgSend.encode(’utf-8’), msg[1])’’’client’’’import socketsk = socket.socket(type=socket.SOCK_DGRAM)server = (’127.0.0.1’, 6000)while True: msgSend = input(’>>>’) if msgSend.upper() == ’Q’:sk.sendto(’對(duì)方和你斷開了連接’.encode(’utf-8’), server)break sk.sendto(msgSend.encode(’utf-8’), server) msg = sk.recv(1024).decode(’utf-8’) if msg.upper() == ’Q’:print(’對(duì)方和你斷開了連接’)break print(msg)4,粘包
只出現(xiàn)在tcp協(xié)議中,因?yàn)閠cp協(xié)議中多條消息之間沒有邊界,并且還有各種優(yōu)化算法,因此會(huì)導(dǎo)致發(fā)送端和接收端都存在粘包現(xiàn)象:
發(fā)送端:兩條消息很短,而且發(fā)送的間隔時(shí)間也很短
接收端:多條消息沒有及時(shí)接收,而在接收方的緩存堆在一起導(dǎo)致粘包
’’’server’’’import socketsk = socket.socket()sk.bind((’127.0.0.1’, 6000))sk.listen()conn, addr = sk.accept()conn.send(b’hello’)conn.send(b’byebye’)conn.close()sk.close()’’’client’’’import timeimport socketsk = socket.socket()sk.connect((’127.0.0.1’, 6000))time.sleep(0.1)msg = sk.recv(5)print(msg)msg = sk.recv(4)print(msg)sk.close()
解決粘包問題的本質(zhì):設(shè)置邊界(發(fā)送長(zhǎng)度、發(fā)送消息,交替進(jìn)行)
1,自定義協(xié)議
’’’server’’’import socketsk = socket.socket()sk.bind((’127.0.0.1’, 6000))sk.listen()conn, addr = sk.accept()msg1 = input(’>>>’).encode(’utf-8’)msg2 = input(’>>>’).encode(’utf-8’)def sendFunc(msg): num = str(len(msg)) ret = num.zfill(4) conn.send(ret.encode(’utf-8’)) conn.send(msg)sendFunc(msg1)sendFunc(msg2)conn.close()sk.close()’’’client’’’import socketsk = socket.socket()sk.connect((’127.0.0.1’, 6000))def receiveFunc(): num = sk.recv(4).decode(’utf-8’) msg = sk.recv(int(num)) print(msg.decode(’utf-8’))receiveFunc()receiveFunc()sk.close()
2,struct模塊
import struct’’’~2**32, 排除符號(hào)位,相當(dāng)于1G的數(shù)據(jù)的長(zhǎng)度’’’num1 = 1231341234num2 = 1342342num3 = 12ret1 = struct.pack(’i’, num1)print(ret1)print(len(ret1))ret2 = struct.pack(’i’, num2)print(ret2)print(len(ret2))ret3 = struct.pack(’i’, num3)print(ret3)print(len(ret3))ret11 = struct.unpack(’i’, ret1)print(ret11)print(type(ret11[0]))
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