1、請自行了解HTTP協議

http://www.cnblogs.com/reboot51/p/8358129.html（點擊跳轉）

2、創建Socket服務，監聽指定IP和端口

3、以阻塞方式等待客戶端連接

4、讀取客戶端請求數據並進行解析

5、準備服務器運行上下文

6、處理客戶端請求數據

7、根據用戶請求路徑讀取文件

8、返回響應結果給客戶端

9、程序入口

10、目錄結構

11、運行

python wsgiserver.py app:run

12、源碼

a.wsgiserver.py文件

#encoding:utf-8

import socket
import StringIO
 
import sys
import logging
from datetime import datetime

logger = logging.getLogger(__name__)

class WSGIServer(object):

    address_family = socket.AF_INET
    socket_type = socket.SOCK_STREAM
    request_queue_size = 30
    recv_size = 1024

    def __init__(self, server_address):
        self._listen_socket 
 
= _listen_socket = socket.socket(self.address_family,
                                                         self.socket_type)       _listen_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR,1)       _listen_socket.bind(server_address)   
       _listen_socket.listen(self.request_queue_size)     
       _host, _port 
 
= _listen_socket.getsockname()
        self._server_name = socket.getfqdn(_host)
        self._server_port = _port
        self._headers_set = []
        self._application = None
        self._client = None
        self._request_data = None
        self._request_method = None
        self._path = None
        self._request_version = None
        self._start_response = None

    def set_application(self, application):
        self._application = application

    def server_forever(self):    
        _listen_socket = self._listen_socket
        logger.info(‘listen on %s:%s‘, self._server_name, self._server_port)      while 1:      
            try:
                self._client, _addr = _listen_socket.accept()
                self._handle_request(_addr)
            except KeyboardInterrupt as e:
                logger.info(‘interrupt‘)
                break
            except BaseException as e:
                logger.error(e)

    def _handle_request(self, client_addr):
        self._request_data = _request_data = self._client.recv(self.recv_size)
        self._parse_request_data(_request_data)       
        _env = self._get_environment(client_addr)   
        _result = self._application(_env, self.start_response)
        self._finish_response(_result)

    def _parse_request_data(self, request_data):    
        _request_line = str(request_data.splitlines()[0]).rstrip(‘\r\n‘)
        (self._request_method, self._path, self._request_version) = _request_line.split()

    def _get_environment(self, client_addr):     
        _env = {}        
        _env[‘wsgi.version‘] = (1, 0)        
        _env[‘wsgi.url_scheme‘] = ‘http‘
        _env[‘wsgi.input‘] = StringIO.StringIO(self._request_data)                _env[‘wsgi.errors‘] = sys.stderr       
        _env[‘wsgi.multithread‘] = False
        _env[‘wsgi.multiprocess‘] = False
        _env[‘wsgi.run_once‘] = False
        _env[‘REQUEST_METHOD‘] = self._request_method.upper()        
        _env[‘PATH_INFO‘] = self._path
        _env[‘SERVER_NAME‘] = self._server_name
        _env[‘SERVER_PORT‘] = self._server_port
        _env[‘HTTP_CLIENT_IP‘] = client_addr[0]

        logger.info(‘%s %s %s %s‘, _env[‘HTTP_CLIENT_IP‘], datetime.now().strftime(‘%Y-%m-%d %H:%M:%S‘), _env[‘REQUEST_METHOD‘], _env[‘PATH_INFO‘])

        return _env

    def start_response(self, status, response_headers, exc_info=None):            _server_headers = [
            (‘Date‘, ‘Sun, 7 Jun 2015 23:07:04 GMT‘),
            (‘Server‘, ‘WSGIServer 0.1‘)
            ]
        self._headers_set = [status, response_headers + _server_headers]

    def _finish_response(self, result):     
        _status, _response_headers = self._headers_set
        _response = ‘HTTP/1.1 {status}\r\n‘.format(status=_status)                for _header in _response_headers:       
        _response += ‘{0}:{1}\r\n‘.format(*_header)       
        _response += ‘\r\n‘
        for _data in result:            
            _response += _data

        self._client.sendall(_response)
        self._client.close()


def make_server(server_address, application):
    server = WSGIServer(server_address)
    server.set_application(application)
    return server
            
if __name__ == ‘__main__‘:
    logging.basicConfig(level=logging.DEBUG)

    server_addr= (‘0.0.0.0‘, 43002)

    app_path = sys.argv[1]
    module, application = app_path.split(‘:‘)
    module = __import__(module)
    application = getattr(module, application)
    httpd = make_server(server_addr, application)
    httpd.server_forever()

b.app.py文件

#encoding:utf-8

import os

class PageNotFoundException(BaseException):
    pass

def render(filename, dirname=‘html‘):
    _path = os.path.join(dirname, filename)
    if os.path.exists(_path):     
       with open(_path, ‘rb‘) as handler:      
           return handler.read()
               
   raise PageNotFoundException(‘file not found:%s‘ % _path)
   
def run(env, start_response):
    _path = env.get(‘PATH_INFO‘)
    response = ‘‘
    try:
        _path = ‘index.html‘ if _path == ‘/‘ else _path[1:]
        if _path.endswith(‘.css‘):
            start_response(‘200 OK‘, [(‘Content-Type‘, ‘text/css‘)])
        elif _path.endswith(‘.js‘):
           start_response(‘200 OK‘, [(‘Content-Type‘, ‘text/javascript‘)]
        elif _path.endswith(‘.html‘):
            start_response(‘200 OK‘, [(‘Content-Type‘, ‘text/html‘)])
        else:
            start_response(‘200 OK‘, [(‘Content-Type‘, ‘text/plain‘), (‘Content-Disposition‘, ‘attachment; filename=%s‘ % os.path.basename(_path))])
        response = render(_path) 
    except PageNotFoundException as e:
        response = render(‘404.html‘)    
    
    return [response, ‘\r\n‘]

Python實現簡易Web服務器