Python BaseHTTPRequestHandler服务器仅适用于第一个GET请求

Question

I'm working on trying create a super basic python webserver based on BaseHTTPRequestHandler. When I perform the GET request to the address 127.0.0.1/a for the first time, everything works well and I recover an image on my browser.

However, when I repeat this GET request a second time, I do not get anything. Tracing the code, I can see that the code itself is running through the entire do_GET(self) segment.

I'm really confused as to why the webserver would work the first time and not the next.

Any and all help is much appreciated.

from http.server import BaseHTTPRequestHandler, HTTPServer  
from os import curdir, sep


imagefile = "a.jpg"
imagepage =open(curdir+sep+imagefile, 'rb')

notfound = "File not found"

class webserverHandler(BaseHTTPRequestHandler):
    def do_OPTIONS(self):
        self.send_response(200)
        self.send_header('Access-Control-Allow-Origin', '*')                
        self.send_header('Access-Control-Allow-Methods', 'GET, POST, OPTIONS')
        self.send_header("Access-Control-Allow-Headers", "X-Requested-With") 

    def do_GET(self):
        if self.path == "/a":
            print("getting thg jpg file")
            self.send_response(200)
            self.send_header("Content-type","image/png")
            self.end_headers()
            self.wfile.write(imagepage.read())
    else:
        self.send_error(404, notfound) 

def main():
    try:
        port = 1234
        server = HTTPServer(('127.0.0.1', port), webserverHandler)
        print("Web server is running on port {}".format(port))
        server.serve_forever()

    except KeyboardInterrupt:
        print("^C entered, stopping web server...")

    finally:
        if server:
            print("closing server")
            server.socket.close()


if __name__ == '__main__':
    main()

Thank you!

Answer 1

def do_GET(self):
    notfound = "File not found"
    if self.path == "/a":
        print("getting thg jpg file")
        self.send_response(200)
        self.send_header("Content-type","image/png")
        self.end_headers()
        imagefile = "fig1.png"
        imagepage =open(curdir+sep+imagefile, 'rb')
        self.wfile.write(imagepage.read())
    else:
        self.send_error(404, notfound) 

Please read file in each request.

Why:
imagepage.read() make file seek to end of the image file, So, we cannot read any data with next imagepage.read() from second request.

---

Or
We can use imageContent = imagepage.read() at first,
and we can send imageContent every request from http.server import BaseHTTPRequestHandler, HTTPServer
from os import curdir, sep

imagefile = "fig1.png"
imagepage =open(curdir+sep+imagefile, 'rb')
imageContent = imagepage.read() # Read Image here

notfound = "File not found"

class webserverHandler(BaseHTTPRequestHandler):
    def do_OPTIONS(self):
        self.send_response(200)
        self.send_header('Access-Control-Allow-Origin', '*')                
        self.send_header('Access-Control-Allow-Methods', 'GET, POST, OPTIONS')
        self.send_header("Access-Control-Allow-Headers", "X-Requested-With") 

    def do_GET(self):
        if self.path == "/a":
            print("getting thg jpg file")
            self.send_response(200)
            self.send_header("Content-type","image/png")
            self.end_headers()
            self.wfile.write(imageContent)
        else:
            self.send_error(404, notfound) 

def main():
    try:
        port = 1234
        server = HTTPServer(('127.0.0.1', port), webserverHandler)
        print("Web server is running on port {}".format(port))
        server.serve_forever()

    except KeyboardInterrupt:
        print("^C entered, stopping web server...")

    finally:
        if server:
            print("closing server")
            server.socket.close()


if __name__ == '__main__':
    main()