[Turn] Python implements a simple web server

Link: https://www.shiyanlou.com/courses/552


#-*- coding:utf-8 -*-
import sys, os, BaseHTTPServer, subprocess

#-------------------------------------------------------------------------------

class ServerException(Exception):
     ''' Server internal error ''' 
    pass

#-------------------------------------------------------------------------------

class base_case(object):
     ''' Condition processing base class '''

    def handle_file(self, handler, full_path):
        try:
            with open(full_path, 'rb') as reader:
                content = reader.read()
            handler.send_content(content)
        except IOError as msg:
            msg = "'{0}' cannot be read: {1}".format(full_path, msg)
            handler.handle_error(msg)

    def index_path(self, handler):
        return os.path.join(handler.full_path, 'index.html')

    def test(self, handler):
        assert False, 'Not implemented.'

    def act(self, handler):
        assert False, 'Not implemented.'

#-------------------------------------------------------------------------------

class case_no_file(base_case):
     ''' file or directory does not exist '''

    def test(self, handler):
        return not os.path.exists(handler.full_path)

    def act(self, handler):
        raise ServerException("'{0}' not found".format(handler.path))

#-------------------------------------------------------------------------------

class case_cgi_file(base_case):
     ''' executable script '''

    def run_cgi(self, handler):
        data = subprocess.check_output(["python", handler.full_path])
        handler.send_content(data)

    def test(self, handler):
        return os.path.isfile(handler.full_path) and \
               handler.full_path.endswith('.py')

    def act(self, handler):
        self.run_cgi(handler)

#-------------------------------------------------------------------------------

class case_existing_file(base_case):
     ''' if the file exists '''

    def test(self, handler):
        return os.path.isfile(handler.full_path)

    def act(self, handler):
        self.handle_file(handler, handler.full_path)

#-------------------------------------------------------------------------------

class case_directory_index_file(base_case):
     ''' Return to the homepage file in the root path '''

    def test(self, handler):
        return os.path.isdir(handler.full_path) and \
               os.path.isfile(self.index_path(handler))

    def act(self, handler):
        self.handle_file(handler, self.index_path(handler))

#-------------------------------------------------------------------------------

class case_always_fail(base_case):
     ''' default processing '''

    def test(self, handler):
        return True

    def act(self, handler):
        raise ServerException("Unknown object '{0}'".format(handler.path))

#-------------------------------------------------------------------------------

class RequestHandler(BaseHTTPServer.BaseHTTPRequestHandler):
    '''
    If the request path is legal, it will return the corresponding processing
    Otherwise return an error page
    '''

    Cases = [case_no_file(),
             case_cgi_file(),
             case_existing_file(),
             case_directory_index_file(),
             case_always_fail()]

    #Error page template 
    Error_Page = """ \
        <html>
        <body>
        <h1>Error accessing {path}</h1>
        <p>{msg}</p>
        </body>
        </html>
        """

    def do_GET(self):
        try:

            #Get the full request path 
            self.full_path = os.getcwd() + self.path

            # Loop through all cases and handle 
            for case in self.Cases:
                 if case.test(self):
                    case.act(self)
                    break

        #Handle exception 
        except Exception as msg:
            self.handle_error(msg)

    def handle_error(self, msg):
        content = self.Error_Page.format(path=self.path, msg=msg)
        self.send_content(content, 404)

    #Send data to the client 
    def send_content(self, content, status=200 ):
        self.send_response(status)
        self.send_header("Content-type", "text/html")
        self.send_header("Content-Length", str(len(content)))
        self.end_headers()
        self.wfile.write(content)

#-------------------------------------------------------------------------------

if __name__ == '__main__':
    serverAddress = ('', 8080)
    server = BaseHTTPServer.HTTPServer(serverAddress, RequestHandler)
    server.serve_forever()

plain.html

<html>
<head>
<title>Plain Page</title>
</head>
<body>
<h1>Plain Page</h1>
<p>Nothin' but HTML.</p>
</body>
</html>

index.html

<html>
<head>
<title>Index Page</title>
</head>
<body>
<h1>Index Page</h1>
<p>Welcome to my home.</p>
</body>
</html>

showtime.py

from datetime import datetime
print '''\
<html>
<body>
<p>Generated {0}</p>
</body>
</html>'''.format(datetime.now())

[Turn] Python implements a simple web server

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