Web框架的引入

为什么会有web框架

有了上一篇内容，静态、动态web服务器的实现，已经掌握了客户端请求到服务器处理的机制。在动态资源处理中，根据请求 .py 导入模块应用，然后调用应用入口程序实现动态处理。但是在真实的项目中，肯定有很多应用（.py文件），按照这种处理机制（每个应用中都要写一个入口，设置状态码、headers）不符合架构设计原则，这一部分肯定是可以复用的，所用应用应该公用一个入口，这就引入一个概念web框架。

设计思路

• 把每个应用中入口 application(env,start_response) 提取到web服务器中，然后在入口中通过路由机制分发到各应用中处理。

代码如下：

- WebFramework.py

`
# coding:utf-8

import time
from MyWebServer import WebServer

HTML_ROOT_DIR = "./static"

class Application(object):
    '''自定义通用的web框架'''

    # 初始化路由信息
    def __init__(self,urls):
        self.urls = urls

    # 匹配路由
    def __call__(self, env, start_response):
        path = env.get("PATH_INFO", "/")
        # /static/index.html
        if path.startswith("/static"):
            file_name = path[7:]
            # 打开文件，读取内容
            try:
                file = open(HTML_ROOT_DIR + file_name, "rb")
            except IOError:
                # 代表未找到路由信息，404错误
                status = "404 Not Found"
                headers = []
                start_response(status, headers)
                return "not found"
            else:
                file_data = file.read()
                file.close()

                status = "200 OK"
                headers = []
                start_response(status, headers)
                return file_data.decode("utf-8")

        for url,handler in self.urls:
            if path == url:
                return handler(env,start_response)
        # 未匹配到
        status = '404 Not Found'
        headers = []
        start_response(status,headers)
        return 'not found'

def showtime(env,start_response):
    status = '200 OK'
    headers = [
        ('Content-Type', 'text/plain')
    ]
    start_response(status, headers)
    return str(time.time())

def sayhello(env,start_response):
    status = '200 OK'
    headers = [
        ('Content-Type','text/plain')
    ]
    start_response(status,headers)
    return 'say hello'

def helloworld(env,start_response):
    status = '200 OK'
    headers =[
        ('Content-Type','text/plain')
    ]
    start_response(status,headers)
    return 'hello world'

if __name__ == '__main__':
    urls = [
        ('/', showtime),
        ('/sayhello',sayhello),
        ('/helloworld',helloworld)
    ]
    app = Application(urls)

    webServer = WebServer(app)
    webServer.bind(8000)
    webServer.start()

`

- MyWebServer.py

`
# coding:utf-8

import socket
import re
import sys

from multiprocessing import Process

HTML_ROOT_DIR = './static'
WSGI_PY = './wsgipy'

class WebServer(object):
    '''
    简单的webserver
    '''

    def __init__(self,application):
        '''application：框架'''
        self.sock_server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        self.sock_server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
        self.app = application

    def start(self):
        self.sock_server.listen(128)
        while True:
            sock_client, addr = self.sock_server.accept()
            print('[%s,%s]用户已连接......' % addr)
            handle_client_process = Process(target=self.handle_client, args=(sock_client,))
            handle_client_process.start()
            sock_client.close()

    def start_response(self, status, headers):
        """
                 status = "200 OK"
            headers = [
                ("Content-Type", "text/plain")
            ]
            star
                """
        resp_headers = 'HTTP/1.1 ' + status + '\r\n'
        for header in headers:
            resp_headers += '%s: %s\r\n' % header

        self.resp_headers = resp_headers

    def handle_client(self, sock_client):
        '''处理客户端请求'''
        recv_data = sock_client.recv(1024)
        #print('请求数据：', recv_data)
        req_lines = recv_data.splitlines()
        #for line in req_lines:
        #    print(line)

        req_start_line = req_lines[0]
        #print(req_start_line.decode('utf-8'))
        file_name = re.match(r"\w+ +(/[^ ]*) ", req_start_line.decode("utf-8")).group(1)
        method = re.match(r"(\w+) +/[^ ]* ", req_start_line.decode("utf-8")).group(1)

        env = {
            "PATH_INFO": file_name,
            "METHOD": method
        }
        response_body = self.app(env, self.start_response)

        response = self.resp_headers + "\r\n" + response_body

        # 向客户端返回响应数据
        sock_client.send(bytes(response, "utf-8"))

        # 关闭客户端连接
        sock_client.close()

    def bind(self, port):
        self.sock_server.bind(('', port))

def main():
    sys.path.insert(1,WSGI_PY)
    webServer = WebServer()
    webServer.bind(8000)
    webServer.start()

if __name__ == '__main__':
    main()

`

启动

入口实在WebFramework.py 中，直接启动该文件，客户端请求指定路径即可看到效果。但是对于大多框架都是通过命令行启动，我们不可能在程序中这样启动，而且对于webserver来说始终是不变得，变的是web框架，所以改造成命令行启动，代码如下：

- WebFramework.py

`
# coding:utf-8

import time

HTML_ROOT_DIR = "./static"

class Application(object):
    '''自定义通用的web框架'''

    # 初始化路由信息
    def __init__(self,urls):
        self.urls = urls

    # 匹配路由
    def __call__(self, env, start_response):
        path = env.get("PATH_INFO", "/")
        # /static/index.html
        if path.startswith("/static"):
            file_name = path[7:]
            # 打开文件，读取内容
            try:
                file = open(HTML_ROOT_DIR + file_name, "rb")
            except IOError:
                # 代表未找到路由信息，404错误
                status = "404 Not Found"
                headers = []
                start_response(status, headers)
                return "not found"
            else:
                file_data = file.read()
                file.close()

                status = "200 OK"
                headers = []
                start_response(status, headers)
                return file_data.decode("utf-8")

        for url,handler in self.urls:
            if path == url:
                return handler(env,start_response)
        # 未匹配到
        status = '404 Not Found'
        headers = []
        start_response(status,headers)
        return 'not found'

def showtime(env,start_response):
    status = '200 OK'
    headers = [
        ('Content-Type', 'text/plain')
    ]
    start_response(status, headers)
    return str(time.time())

def sayhello(env,start_response):
    status = '200 OK'
    headers = [
        ('Content-Type','text/plain')
    ]
    start_response(status,headers)
    return 'say hello'

def helloworld(env,start_response):
    status = '200 OK'
    headers =[
        ('Content-Type','text/plain')
    ]
    start_response(status,headers)
    return 'hello world'

urls = [
    ('/', showtime),
    ('/sayhello',sayhello),
    ('/helloworld',helloworld)
]
app = Application(urls)
# if __name__ == '__main__':
#     urls = [
#         ('/', showtime),
#         ('/sayhello',sayhello),
#         ('/helloworld',helloworld)
#     ]
#     app = Application(urls)
#
#     webServer = WebServer(app)
#     webServer.bind(8000)
#     webServer.start()
`

- MyWebServer.py

`
# coding:utf-8

import socket
import re
import sys

from multiprocessing import Process

HTML_ROOT_DIR = './static'
WSGI_PY = './wsgipy'

class WebServer(object):
    '''
    简单的webserver
    '''

    def __init__(self,application):
        '''application：框架'''
        self.sock_server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        self.sock_server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
        self.app = application

    def start(self):
        self.sock_server.listen(128)
        while True:
            sock_client, addr = self.sock_server.accept()
            print('[%s,%s]用户已连接......' % addr)
            handle_client_process = Process(target=self.handle_client, args=(sock_client,))
            handle_client_process.start()
            sock_client.close()

    def start_response(self, status, headers):
        """
                 status = "200 OK"
            headers = [
                ("Content-Type", "text/plain")
            ]
            star
                """
        resp_headers = 'HTTP/1.1 ' + status + '\r\n'
        for header in headers:
            resp_headers += '%s: %s\r\n' % header

        self.resp_headers = resp_headers

    def handle_client(self, sock_client):
        '''处理客户端请求'''
        recv_data = sock_client.recv(1024)
        #print('请求数据：', recv_data)
        req_lines = recv_data.splitlines()
        #for line in req_lines:
        #    print(line)

        req_start_line = req_lines[0]
        #print(req_start_line.decode('utf-8'))
        file_name = re.match(r"\w+ +(/[^ ]*) ", req_start_line.decode("utf-8")).group(1)
        method = re.match(r"(\w+) +/[^ ]* ", req_start_line.decode("utf-8")).group(1)

        env = {
            "PATH_INFO": file_name,
            "METHOD": method
        }
        response_body = self.app(env, self.start_response)

        response = self.resp_headers + "\r\n" + response_body

        # 向客户端返回响应数据
        sock_client.send(bytes(response, "utf-8"))

        # 关闭客户端连接
        sock_client.close()

    def bind(self, port):
        self.sock_server.bind(('', port))

def main():
    sys.path.insert(1,WSGI_PY)
    if len(sys.argv) < 2:
        sys.exit("python MyWebServer.py Module:app")
    module_name, app_name = sys.argv[1].split(':')
    m = __import__(module_name)
    app = getattr(m,app_name)
    webServer = WebServer(app)
    webServer.bind(8000)
    webServer.start()

if __name__ == '__main__':
    main()
`

调用方式

在命令行中，执行如下命令即可启动webserver服务，模块名称：应用框架名， 其中这里的app指的是WebFramework.py中Application类的实例，其实也就是应用框架的实例。后续自定义框架的时候，直接调用即可。

`
python MyWebServer.py WebFramework:app
`

代码已上传到github：python 小程序