restframework api（基础2）

一 socket简介

1 最简单的socket

#################server
import socket
ip_port = ('127.0.0.1',9997)
sk = socket.socket()
sk.bind(ip_port)
sk.listen(5)

print('server waiting...')

conn,addr = sk.accept()
client_data = conn.recv(1024)
print(str(client_data,"utf8"))
conn.sendall(bytes('滚蛋!',encoding="utf-8"))

sk.close()


################client
import socket
ip_port = ('127.0.0.1',9997)

sk = socket.socket()
sk.connect(ip_port)


sk.sendall(bytes('俺喜欢你',encoding="utf8"))

server_reply = sk.recv(1024)
print (str(server_reply,"utf8"))

　　

上面主要就是服务器端启动，并监听端口等待客户端连接，客户端连接发送一个“俺喜欢你”，服务器回复“滚蛋”，这个是最简单的SOCKET的流程了。

2 socket的写一个简单的web应用

这里主要是使用浏览器模拟socket的客户端，server端自己实现。

# 对于所有的Web应用，本质上其实就是一个socket服务端，用户的浏览器其实就是一个socket客户端。

import socket

def handle_request(client):
    buf = client.recv(1024)  # 接收浏览器发送的内容
    print(buf)
    client.send('HTTP/1.1 201 OK 

'.encode('gbk')) # 向浏览器发送包头状态码
    client.send('<h1>你好，世界 ! </h1>'.encode('gbk'))  # 向浏览器发送内容

def main():
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    sock.bind(('localhost',8000))
    sock.listen(5)

    while True:
        # 这个conn是client的socket对象，相当于client主动和server建立了一条通道
        conn,add = sock.accept()
        handle_request(conn)
        conn.close()

if __name__ == '__main__':
    main()

　　

可以看到server端启动之后，会创建一个sock对象，然后绑定ip:port，进行监听浏览器的连接，这个先接收浏览器发送过来的内容，然后向浏览器发送一个包头，一个内容。这个包头浏览器可以自动识别。

所以这里可以看到web应用其实本质上是一个socket的server端，浏览器本质上是一个socket的client端。所有的其他都是基于这里来不断的进行丰富。

具体浏览器向我们server端发送了些什么

"E:softwarepython3.6install dirpython.exe" E:/workspace/django_flow/app01/tests.py
b'GET / HTTP/1.1
Host: localhost:8000
Connection: keep-alive
Cache-Control: max-age=0
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.36
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Accept-Encoding: gzip, deflate, sdch, br
Accept-Language: zh-CN,zh;q=0.8
HT-Ver: 1.1.2
HT-Sid: QR8okFW9-0F6VyaG0-VMYijoqf-eENDjuaW-qsT4qDpV-LWRAthtW-yqDF5U7/-vaL3Hjav

'
b'GET /favicon.ico HTTP/1.1
Host: localhost:8000
Connection: keep-alive
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.36
Accept: image/webp,image/*,*/*;q=0.8
Referer: http://localhost:8000/
Accept-Encoding: gzip, deflate, sdch, br
Accept-Language: zh-CN,zh;q=0.8
HT-Ver: 1.1.2
HT-Sid: QR8okFW9-0F6VyaG0-VMYijoqf-eENDjuaW-qsT4qDpV-LWRAthtW-yqDF5U7/-vaL3Hjav

'

　　

二 wsgiref源码分析

from wsgiref.simple_server import make_server

# python3默认str是unicode，这里需要bytes，所以需要encode转换一下
def application(environ,start_response):
    start_response('200 OK', [('Content-Type','text/html')])
    return ['<h1> 你好，世界！</h1>'.encode('gbk')]

httpd = make_server('localhost',8080,application)
print('Saving HTTP on port 8080')

httpd.serve_forever()

上面的代码运行之后就是一个web应用了。

下面对上面的代码进行分析。

1 首先执行   httpd = make_server('localhost',8080,application)

2 然后执行   httpd.serve_forever()

首先我们分析第一步，

def make_server(
    host, port, app, server_class=WSGIServer, handler_class=WSGIRequestHandler
):
    """Create a new WSGI server listening on `host` and `port` for `app`"""
    # 这里先执行WSGIServer类的初始化工作，其中handler_class=WSGIRequestHandler
    server = server_class((host, port), handler_class)
    server.set_app(app)
    return server

　

首先，make_server是一个函数，接收host,port,app等参数。看样子这个函数返回的是一个server对象。也就是WSGIServer类的对象。

这里使用server_class进行了类的初始化，(host,port)是一个数组，handler_class= WSGIRequestHandler是一个类，然后执行server.set_app(app)，这里的app就是上面的application。

server_class类

class WSGIServer(HTTPServer):

    """BaseHTTPServer that implements the Python WSGI protocol"""

    application = None

    def server_bind(self):
        """Override server_bind to store the server name."""
        HTTPServer.server_bind(self)
        self.setup_environ()

    def setup_environ(self):
        # Set up base environment
        env = self.base_environ = {}
        env['SERVER_NAME'] = self.server_name
        env['GATEWAY_INTERFACE'] = 'CGI/1.1'
        env['SERVER_PORT'] = str(self.server_port)
        env['REMOTE_HOST']=''
        env['CONTENT_LENGTH']=''
        env['SCRIPT_NAME'] = ''

    def get_app(self):
        return self.application

    def set_app(self,application):
        self.application = application

　

先来分析server实例化的过程：跑题了

1）WSGIServer类并没有__init__()，所以需要到HTTPServer类中进行查找

这里关于继承有2中查找方法：

经典类：深度优先

新式类：广度优先

好了，补充完毕，至于神马是经典类，神马是新式类。继承了object的类叫新式类，不继承的那就是经典类。简单吧

2）查看HTTPSserver类

class HTTPServer(socketserver.TCPServer):

    allow_reuse_address = 1    # Seems to make sense in testing environment

    def server_bind(self):
        """Override server_bind to store the server name."""
        socketserver.TCPServer.server_bind(self)
        host, port = self.server_address[:2]
        self.server_name = socket.getfqdn(host)
        self.server_port = port

　　

这里类也没有__init__()方法，继续查看TCPServer吧。好吧这类TCPServer类不但有__init__()，还需要执行父类的__init__()

　　

　

handler_class类

class WSGIRequestHandler(BaseHTTPRequestHandler):

    server_version = "WSGIServer/" + __version__

    def get_environ(self):
        env = self.server.base_environ.copy()
        env['SERVER_PROTOCOL'] = self.request_version
        env['SERVER_SOFTWARE'] = self.server_version
        env['REQUEST_METHOD'] = self.command
        if '?' in self.path:
            path,query = self.path.split('?',1)
        else:
            path,query = self.path,''

        env['PATH_INFO'] = urllib.parse.unquote(path, 'iso-8859-1')
        env['QUERY_STRING'] = query

        host = self.address_string()
        if host != self.client_address[0]:
            env['REMOTE_HOST'] = host
        env['REMOTE_ADDR'] = self.client_address[0]

        if self.headers.get('content-type') is None:
            env['CONTENT_TYPE'] = self.headers.get_content_type()
        else:
            env['CONTENT_TYPE'] = self.headers['content-type']

        length = self.headers.get('content-length')
        if length:
            env['CONTENT_LENGTH'] = length

        for k, v in self.headers.items():
            k=k.replace('-','_').upper(); v=v.strip()
            if k in env:
                continue                    # skip content length, type,etc.
            if 'HTTP_'+k in env:
                env['HTTP_'+k] += ','+v     # comma-separate multiple headers
            else:
                env['HTTP_'+k] = v
        return env

    def get_stderr(self):
        return sys.stderr

    def handle(self):
        """Handle a single HTTP request"""

        self.raw_requestline = self.rfile.readline(65537)
        if len(self.raw_requestline) > 65536:
            self.requestline = ''
            self.request_version = ''
            self.command = ''
            self.send_error(414)
            return

        if not self.parse_request(): # An error code has been sent, just exit
            return

        handler = ServerHandler(
            self.rfile, self.wfile, self.get_stderr(), self.get_environ()
        )
        handler.request_handler = self      # backpointer for logging
        handler.run(self.server.get_app())