python---wsgiref初探
wsgiref使用
from wsgiref.simple_server import make_server from urls import URLS def RunServer(environ, start_respone): start_respone('200 OK',[('Content-Type','text/html')]); url = environ['PATH_INFO'] #用户访问路径 ret = "<h1 style='color:red;'>404</h1>" return ret def run(): httpd=make_server('',8080,RunServer) httpd.serve_forever()
探究make_server以及serve_forever和自定义处理函数RunServer之间的关系
def RunServer(environ, start_respone): start_respone('200 OK',[('Content-Type','text/html')]); return '<h1>Hello World</h1>' if __name__ == "__main__": httpd=make_server('',8080,RunServer) httpd.serve_forever()
首先追踪make_server:发现返回WSGIServer对象，其中WSGIServer与WSGIRequestHandler存在联系（一个用于客户端连接，一个用于调用自定义函数处理数据），那他们是如何关联和调用自定义函数是今天所需要探讨的
def make_server( host, port, app, server_class=WSGIServer, handler_class=WSGIRequestHandler ): server = server_class((host, port), handler_class) server.set_app(app) return server
1.开始追踪WSGIServer类
server = server_class((host, port), handler_class) #因为server_class=WSGIServer所有开始向上查找构造函数 class WSGIServer(HTTPServer): class HTTPServer(socketserver.TCPServer): class TCPServer(BaseServer): def __init__(self, server_address, RequestHandlerClass, bind_and_activate=True): //上面handler_class BaseServer.__init__(self, server_address, RequestHandlerClass)
在父类TCPServer中找到构造函数，也发现了与WSGIRequestHandler的联系，继续查找父类BaseServer
class BaseServer: def __init__(self, server_address, RequestHandlerClass): def serve_forever(self, poll_interval=0.5): if ready: self._handle_request_noblock() def _handle_request_noblock(self): try: self.process_request(request, client_address) except: def process_request(self, request, client_address): self.finish_request(request, client_address) def finish_request(self, request, client_address): 注 self.RequestHandlerClass(request, client_address, self)
最终我们会调用这里面的serve_forever函数，而这里我们调用到（注）处的处理类，并且进行了构造
2.可以开始追踪handler_class=WSGIRequestHandler类，看是如何处理数据，对于上面（注）处调用初始化开始
此处对应上面的注处 class BaseHTTPRequestHandler(socketserver.StreamRequestHandler)://中含有构造函数 def __init__(self, request, client_address, server): self.request = request self.client_address = client_address self.server = server self.setup() try: self.handle() finally: self.finish()
发现需要找到handle函数，而我们在WSGIServer对象中进行使用的类是其子类，
handler_class=WSGIRequestHandler
所有向先寻找handle函数，最后一次在子类中出现位置是在WSGIRequestHandler中
class WSGIRequestHandler(BaseHTTPRequestHandler): def handle(self): handler = ServerHandler( self.rfile, stdout, self.get_stderr(), self.get_environ() ) handler.run(self.server.get_app())
他又构造了ServerHandler对象，并且向其中传入了自己的数据进行构造，运行了ServerHandler对象中的run方法
先向上查找构造方法
class ServerHandler(SimpleHandler): #在父类中找到 class SimpleHandler(BaseHandler): def __init__(self,stdin,stdout,stderr,environ, multithread=True, multiprocess=False ): self.stdin = stdin self.stdout = stdout self.stderr = stderr self.base_env = environ self.wsgi_multithread = multithread self.wsgi_multiprocess = multiprocess
开始查找run方法，发现在父类BaseHandler中
class BaseHandler: def run(self, application): self.setup_environ() self.result = application(self.environ, self.start_response) def setup_environ(self) env = self.environ = self.os_environ.copy() self.add_cgi_vars() env['wsgi.input'] = self.get_stdin() env['wsgi.errors'] = self.get_stderr() env['wsgi.version'] = self.wsgi_version env['wsgi.run_once'] = self.wsgi_run_once env['wsgi.url_scheme'] = self.get_scheme() env['wsgi.multithread'] = self.wsgi_multithread env['wsgi.multiprocess'] = self.wsgi_multiprocess if self.wsgi_file_wrapper is not None: env['wsgi.file_wrapper'] = self.wsgi_file_wrapper if self.origin_server and self.server_software: env.setdefault('SERVER_SOFTWARE',self.server_software) def start_response(self, status, headers,exc_info=None): """'start_response()' callable as specified by PEP 3333""" if exc_info: try: if self.headers_sent: # Re-raise original exception if headers sent raise exc_info[0](exc_info[1]).with_traceback(exc_info[2]) finally: exc_info = None # avoid dangling circular ref elif self.headers is not None: raise AssertionError("Headers already set!") self.status = status self.headers = self.headers_class(headers) status = self._convert_string_type(status, "Status") assert len(status)>=4,"Status must be at least 4 characters" assert status[:3].isdigit(), "Status message must begin w/3-digit code" assert status[3]==" ", "Status message must have a space after code" if __debug__: for name, val in headers: name = self._convert_string_type(name, "Header name") val = self._convert_string_type(val, "Header value") assert not is_hop_by_hop(name),"Hop-by-hop headers not allowed" return self.write
最终运行了函数application，而application则是我们传入的自定义函数RunServer
def make_server( host, port, app, server_class=WSGIServer, handler_class=WSGIRequestHandler ): """Create a new WSGI server listening on `host` and `port` for `app`""" server = server_class((host, port), handler_class) server.set_app(app) return server #app为传入函数
class WSGIServer(HTTPServer): def set_app(self,application): self.application = application
而WSGServer则是server_class=WSGIServer中的父类
所以最终数据都传入到了
server = server_class((host, port), handler_class)
server对象中返回给用户调用
而且由上面
self.result = application(self.environ, self.start_response)
我们可以知道自定义函数RunServer(environ,start_response)中的两个参数必须加上，其各自代表了
env['wsgi.input'] = self.get_stdin() env['wsgi.errors'] = self.get_stderr() env['wsgi.version'] = self.wsgi_version ...... 信息列表
以及
def start_response(self, status, headers,exc_info=None): 函数
