什么叫做黏包？
先写一个小补充：
encode()函数、decode()函数:
encode() 是将数据类型转换成bytes类型
decode()是将bytes类型转换成其他类型
encode() 叫做编码， decode( ) 叫做解码
通过一段代码来引出黏包现象（基于TCP的网络通信）
sever端
import socket sk = socket.socket() sk.bind(('127.0.0.1', 8080)) sk.listen() conn, addr = sk.accept() while True: cmd = input('>>>') conn.send((cmd.encode('utf-8'))) # 将输入的数据转换层(utf-8)的bytes类型，用于网络传输 ret = conn.recv(1024).decode('utf-8') # 将接收到的数据(utf-8)的bytes类型数据，解码成本身的数据类型 print(ret) conn.close() sk.close()
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import socket
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sk = socket.socket()
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sk.bind(('127.0.0.1', 8080))
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sk.listen()
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conn, addr = sk.accept()
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while True:
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cmd = input('>>>')
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conn.send((cmd.encode('utf-8'))) # 将输入的数据转换层(utf-8)的bytes类型，用于网络传输
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ret = conn.recv(1024).decode('utf-8') # 将接收到的数据(utf-8)的bytes类型数据，解码成本身的数据类型
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print(ret)
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conn.close()
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sk.close()
client端
import socket import subprocess sk = socket.socket() sk.connect(('127.0.0.1', 8080)) while True: cmd = sk.recv(1024).decode('utf-8') ret = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE) std_out = 'stdout :' + (ret.stdout.read()).decode('gbk') std_err = 'stderr :' + (ret.stderr.read()).decode('gbk') print(std_out) print(std_err) sk.send(std_out.encode('utf-8')) sk.send(std_err.encode('utf-8')) sk.close()
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import socket
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import subprocess
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sk = socket.socket()
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sk.connect(('127.0.0.1', 8080))
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while True:
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cmd = sk.recv(1024).decode('utf-8')
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ret = subprocess.Popen(cmd, shell=True,
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stdout=subprocess.PIPE,
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stderr=subprocess.PIPE)
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std_out = 'stdout :' + (ret.stdout.read()).decode('gbk')
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std_err = 'stderr :' + (ret.stderr.read()).decode('gbk')
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print(std_out)
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print(std_err)
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sk.send(std_out.encode('utf-8'))
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sk.send(std_err.encode('utf-8'))
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sk.close()
仔细观察控制台这个时候会发现基于TCP连接从server端发送指令时，会接收一些并不完整的数据，在一次从server端发送指令时，client端会发送上一次断点的数据给server端，我们把这种现象叫做黏包！
基于UDP协议的黏包现象（ps：不存在）
udp_server
import socket sk = socket.socket(type=socket.SOCK_DGRAM) sk.bind(('127.0.0.1', 8091)) msg, addr = sk.recvfrom(1024) while True: cmd = input('>>>') if cmd == 'q': break sk.sendto(cmd.encode('utf-8'), addr) msg, addr = sk.recvfrom(1024) # 两次发送、两次接收 print(msg.decode('utf-8')) msg, addr = sk.recvfrom(1024) print(msg.decode('utf-8')) sk.close()
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import socket
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sk = socket.socket(type=socket.SOCK_DGRAM)
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sk.bind(('127.0.0.1', 8091))
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msg, addr = sk.recvfrom(1024)
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while True:
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cmd = input('>>>')
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if cmd == 'q':
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break
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sk.sendto(cmd.encode('utf-8'), addr)
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msg, addr = sk.recvfrom(1024) # 两次发送、两次接收
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print(msg.decode('utf-8'))
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msg, addr = sk.recvfrom(1024)
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print(msg.decode('utf-8'))
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sk.close()
udp_client
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import socket
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import subprocess
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sk = socket.socket(type=socket.SOCK_DGRAM)
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addr = ('127.0.0.1', 8091)
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sk.sendto('吃了吗？'.encode('utf-8'), addr)
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while True:
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cmd, addr = sk.recvfrom(1024)
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ret = subprocess.Popen(cmd.decode('gbk'), # 这里转码与解码的方式前后不一致，但发送过来的数据是英文。所以无妨！
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shell=True,
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stdout=subprocess.PIPE,
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stderr=subprocess.PIPE
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)
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std_out = 'stdout: ' + (ret.stdout.read()).decode('gbk')
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std_err = 'stderr: ' + (ret.stderr.read()).decode('gbk')
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print(std_out)
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print(std_err)
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sk.sendto(std_out.encode('utf-8'), addr)
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sk.sendto(std_err.encode('utf-8'), addr)
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sk.close()
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