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python简易web服务器学习笔记(二)

时间:2017-03-19 14:12:15      阅读:247      评论:0      收藏:0      [点我收藏+]

标签:inf   它的   return   text   something   with   imp   isp   hand   

import BaseHTTPServer

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

class RequestHandler(BaseHTTPServer.BaseHTTPRequestHandler):
    ‘‘‘Respond to HTTP requests with info about the request.‘‘‘

    # Template for page to send back.
    Page = ‘‘‘<html>
<body>
<table>
<tr>  <td>Header</td>         <td>Value</td>          </tr>
<tr>  <td>Date and time</td>  <td>{date_time}</td>    </tr>
<tr>  <td>Client host</td>    <td>{client_host}</td>  </tr>
<tr>  <td>Client port</td>    <td>{client_port}s</td> </tr>
<tr>  <td>Command</td>        <td>{command}</td>      </tr>
<tr>  <td>Path</td>           <td>{path}</td>         </tr>
</table>
</body>
</html>
‘‘‘

    # Handle a request by constructing an HTML page that echoes the
    # request back to the caller.
    def do_GET(self):
        page = self.create_page()
        self.send_page(page)

    # Create an information page to send.
    def create_page(self):
        values = {
            ‘date_time‘   : self.date_time_string(),
            ‘client_host‘ : self.client_address[0],
            ‘client_port‘ : self.client_address[1],
            ‘command‘     : self.command,
            ‘path‘        : self.path
        }
        page = self.Page.format(**values)
        return page

    # Send the created page.
    def send_page(self, page):
        self.send_response(200)
        self.send_header("Content-type", "text/html")
        self.send_header("Content-Length", str(len(page)))
        self.end_headers()
        self.wfile.write(page)

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

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

上述代码可以输出调试信息。

下一步我们需要让服务器能够提供静态文件。首先我们要做的,是异常处理

import sys, os, BaseHTTPServer

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

class ServerException(Exception):
    ‘‘‘For internal error reporting.‘‘‘
    pass

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

class RequestHandler(BaseHTTPServer.BaseHTTPRequestHandler):
    ‘‘‘
    If the requested path maps to a file, that file is served.
    If anything goes wrong, an error page is constructed.
    ‘‘‘

    # How to display an error.
    Error_Page = """        <html>
        <body>
        <h1>Error accessing {path}</h1>
        <p>{msg}</p>
        </body>
        </html>
        """

    # Classify and handle request.
    def do_GET(self):
        try:

            # Figure out what exactly is being requested.
            full_path = os.getcwd() + self.path

            # It doesn‘t exist...
            if not os.path.exists(full_path):
                raise ServerException("‘{0}‘ not found".format(self.path))

            # ...it‘s a file...
            elif os.path.isfile(full_path):
                self.handle_file(full_path)

            # ...it‘s something we don‘t handle.
            else:
                raise ServerException("Unknown object ‘{0}‘".format(self.path))

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

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

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

    # Send actual content.
    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()

 假设程序允许使用该目录下的任何文件提供服务,它会结合url提供的路径(以‘/‘开始,BaseHTTPServer会自动将它放入self.path),以获取用户想要的文件路径。若文件不存在,或者路径并不指向文件,上述方法将通过获取并抛出异常来报告错误。若匹配到文件,do_GET方法将调用handfile来读取并返回内容,然后调用send_content将文件内容返回给客户端。哇,显然我们是以二进制方式打开的文件(由‘rb‘和‘b‘标识),并把整个文件读到中的呢,所以这样的方法不能处理大型程序喔

其中的细节在于,其中的hand_error,如果我们直接send_content(content)一个错误页面,则返回码是200。这样的错误信息不好判别:hand_error处理的是页面找不到的情况,应该返回404才对。

os是python的基础模块,上述代码中用来获取文件路径。raise就是用抛出异常的。具体用发是和try,except配合使用。若print一些调试信息,就能清楚的看到它的过程了

 

python简易web服务器学习笔记(二)

标签:inf   它的   return   text   something   with   imp   isp   hand   

原文地址:http://www.cnblogs.com/bitch1319453/p/6579574.html

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