简单的python 3 Web服务器在浏览器中显示图像

Question

I'm trying to make a simple http server that can get accessed through a web browser as the client, only using the sockets module from python 3. I already got some understanding of how the http response works with its headers. I actually confirmed through Chrome developer tool that the browser is able to comprehend my response, but the image fails to display (it only shows a black screen in the browser, meaning that there is a problem with the image). My guess is that I'm concatenating incorrectly the body of the image to the response String, or I'm encoding it incorrectly. Here is my code:

import socket
import base64
import os

HOST_N = socket.gethostname()
HOST, PORT = socket.gethostbyname(HOST_N), 10080

print(HOST)

listen_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM, socket.IPPROTO_IP) 
listen_socket.bind((HOST, PORT))
listen_socket.listen(1)
print('Serving HTTP on port %s ...' % PORT)
while True:
    client_connection, client_address = listen_socket.accept()
    request = client_connection.recv(1024)
    option = request.decode().split(' ')
    print(request)

    if option[1]:

        if option[1]=='/success.jpg':

            with open("success.jpg", "r+b") as image_file:
                encoded_string = base64.b64encode(image_file.read())
                size = str(os.path.getsize("success.jpg"))

                HTTP_RESPONSE = "HTTP/1.1 200 OK\r\n" + "Connection: close\r\n" + "Content-Type: image/jpg\r\n" + "Content-Lenght: "+ size + "\r\n\r\n" + str(encoded_string)

                print(HTTP_RESPONSE)
                client_connection.sendall(HTTP_RESPONSE.encode('ASCII'))



        else:

            with open("404.jpg", "r+b") as image_file:
                encoded_string = base64.b64encode(image_file.read())
                size = str(os.path.getsize("404.jpg"))

                HTTP_RESPONSE = "HTTP/1.1 200 OK\n" + "Connection: close\n" + "Content-Type: image/jpg\n" + "Content-Lenght: "+ size + "\n\n" + str(encoded_string)

                client_connection.sendto(HTTP_RESPONSE.encode('ASCII'), (HOST, PORT))

    else:
        pass    

    client_connection.close()

Currently using python 3.5.2 and elementary OS 0.4.1 Loki.

Answer 1

You have a typo in content length also could save cpu, no need for encoding since you announce a binary content with content type:

#
data = image_file.read()
HTTP_RESPONSE = b'\r\n'.join([
    b"HTTP/1.1 200 OK",
    b"Connection: close",
    b"Content-Type: image/jpg",
    bytes("Content-Length: %s" % len(data),'utf-8'),
    b'', data 
] )
client_connection.sendall(HTTP_RESPONSE) 
#

on a side note if you encode content, then you must announce size of encoded content ( in bytes ), not the size of source data (file).

Answer 2

what you need is the exact size of bytes sent, which actually is the file size and not its utf-8 representation you have got with len():

size = str(os.stat('404.jpg').st_size)

hope this helps.