Python Socket TypeError: a bytes-like object is required, not 'str' 錯誤提示

在學習socket編程時，遇到代碼返回如下錯誤： TypeError: a bytes-like object is required, not 'str' 
發現這里python3.5和Python2.7在套接字返回值解碼上有區別。 

首先可以明確，在python3中默認的編碼方式是unicode。unicode 分為 utf-32(占4個字節),utf-16(占兩個字節)，utf-8(占1-4個字節)，因此 utf-16就是現在最常用的unicode版本。 不過考慮到utf8省空間，在文件里存的還是utf-8。

書中示例

服務端

#coding=utf-8
#創建TCP服務器
from socket import *
from time import ctime

HOST=''
PORT=21567
BUFSIZ=1024
ADDR=(HOST,PORT)

tcpSerSock=socket(AF_INET,SOCK_STREAM) #創服務器套接字
tcpSerSock.bind(ADDR) #套接字與地址綁定
tcpSerSock.listen(5)  #監聽連接,傳入連接請求的最大數

while True:
    print('waiting for connection...')
    tcpCliSock,addr =tcpSerSock.accept()
    print('...connected from:',addr)

    while True:
        data =tcpCliSock.recv(BUFSIZ)
        #print('date=',data)
        if not data:
            break
        tcpCliSock.send(('[%s] %s' %(ctime(),data)))

    tcpCliSock.close()
tcpSerSock.close()

客戶端

#coding=utf-8

from socket import *

HOST = 'localhost' #  or 'localhost'
PORT = 21567
BUFSIZ = 1024
ADDR=(HOST,PORT)

tcpCliSock = socket(AF_INET,SOCK_STREAM)
tcpCliSock.connect(ADDR)

while True:
    data = input('> ')
    print('data=',data);
    if not data:
        break
    tcpCliSock.send(data)
    data = tcpCliSock.recv(BUFSIZ)
    if not data:
        break
    print(data)

tcpCliSock.close() 

返回的錯誤提示： 
TypeError: a bytes-like object is required, not ‘str’ 

輸入信息時，在客戶端輸入的是字符串(str類型)，而代碼中需要的是bytes類型，帶着疑問去查原因，最終在StackOverflow上發現有人也出現同樣的問題，且一個叫Scharron的人給出了解答：  

    In python 3, bytes strings and unicodestrings are now two different types. Since sockets are not aware of string encodings, they are using raw bytes strings, that have a slightly differentinterface from unicode strings.

So, now, whenever you have a unicode string that you need to use as a byte string, you need to encode() it. And whenyou have a byte string, you need to decode it to use it as a regular(python 2.x) string.

Unicode strings are quotes enclosedstrings. Bytes strings are being enclosed strings.

When you use client_socket.send(data),replace it by client_socket.send(data.encode()). When you get datausing data = client_socket.recv(512), replace it by data =client_socket.recv(512).decode()

因此，客戶端傳輸信息時需要解碼把  str類型  轉換 bytes類型 用於傳輸，在接收到服務端信息后，需要進行編碼，再把 bytes類型 轉換成 str類型

以下為修改后的代碼：

服務端

#coding=utf-8
#創建TCP服務器
from socket import *
from time import ctime

HOST=''
PORT=21567
BUFSIZ=1024
ADDR=(HOST,PORT)

tcpSerSock=socket(AF_INET,SOCK_STREAM) #創服務器套接字
tcpSerSock.bind(ADDR) #套接字與地址綁定
tcpSerSock.listen(5)  #監聽連接,傳入連接請求的最大數

while True:
    print('waiting for connection...')
    tcpCliSock,addr =tcpSerSock.accept()
    print('...connected from:',addr)

    while True:
        data =tcpCliSock.recv(BUFSIZ).decode()
        print('date=',data)
        if not data:
            break
        tcpCliSock.send(('[%s] %s' %(ctime(),data)).encode())

    tcpCliSock.close()
tcpSerSock.close()

客戶端

#coding=utf-8
#創建TCP服務器
from socket import *
from time import ctime

HOST=''
PORT=21567
BUFSIZ=1024
ADDR=(HOST,PORT)

tcpSerSock=socket(AF_INET,SOCK_STREAM) #創服務器套接字
tcpSerSock.bind(ADDR) #套接字與地址綁定
tcpSerSock.listen(5)  #監聽連接,傳入連接請求的最大數

while True:
    print('waiting for connection...')
    tcpCliSock,addr =tcpSerSock.accept()
    print('...connected from:',addr)

    while True:
        data =tcpCliSock.recv(BUFSIZ).decode()
        print('date=',data)
        if not data:
            break
        tcpCliSock.send(('[%s] %s' %(ctime(),data)).encode())

    tcpCliSock.close()
tcpSerSock.close()

歡迎各位指正問題