Python无依赖轻量级Web框架xweb：低于500行代码如何实现？

这个xweb框架的实现思路挺有意思的。核心就是基于Python标准库，用最少的代码实现基本的路由和请求处理。

下面是一个简化版的实现，大概100多行就能跑起来：

import socket
import re
from urllib.parse import parse_qs, urlparse
from http.server import BaseHTTPRequestHandler
from io import BytesIO

class Request:
    def __init__(self, method, path, headers, body):
        self.method = method
        self.path = path
        self.headers = headers
        self.body = body
        self.query = {}
        if '?' in path:
            self.path, query_string = path.split('?', 1)
            self.query = parse_qs(query_string)

class Response:
    def __init__(self, body='', status=200, content_type='text/html'):
        self.body = body
        self.status = status
        self.content_type = content_type

class XWeb:
    def __init__(self):
        self.routes = {}
        self.middlewares = []
    
    def route(self, path, methods=['GET']):
        def decorator(handler):
            for method in methods:
                self.routes[(method.upper(), path)] = handler
            return handler
        return decorator
    
    def add_middleware(self, middleware):
        self.middlewares.append(middleware)
    
    def handle_request(self, request):
        # 中间件处理
        for middleware in self.middlewares:
            request = middleware(request)
        
        # 路由匹配
        handler = self.routes.get((request.method, request.path))
        if handler:
            return handler(request)
        return Response('Not Found', 404)
    
    def run(self, host='127.0.0.1', port=8000):
        with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as server:
            server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
            server.bind((host, port))
            server.listen(5)
            print(f"Server running on http://{host}:{port}")
            
            while True:
                conn, addr = server.accept()
                with conn:
                    data = conn.recv(1024)
                    if data:
                        # 解析HTTP请求
                        request_line, *headers_body = data.decode().split('\r\n', 1)
                        method, path, _ = request_line.split()
                        
                        # 解析headers
                        headers_part, body_part = headers_body[0].split('\r\n\r\n', 1) if '\r\n\r\n' in headers_body[0] else (headers_body[0], '')
                        headers = {}
                        for line in headers_part.split('\r\n'):
                            if ': ' in line:
                                key, value = line.split(': ', 1)
                                headers[key] = value
                        
                        request = Request(method, path, headers, body_part)
                        response = self.handle_request(request)
                        
                        # 构建HTTP响应
                        response_headers = f"HTTP/1.1 {response.status} OK\r\n"
                        response_headers += f"Content-Type: {response.content_type}\r\n"
                        response_headers += f"Content-Length: {len(response.body)}\r\n"
                        response_headers += "\r\n"
                        
                        conn.sendall(response_headers.encode() + response.body.encode())

# 使用示例
app = XWeb()

@app.route('/')
def home(request):
    return Response('<h1>Hello XWeb!</h1>')

@app.route('/api/data', methods=['GET', 'POST'])
def api_data(request):
    if request.method == 'GET':
        return Response('{"status": "ok"}', content_type='application/json')
    else:
        return Response('{"status": "created"}', 201, 'application/json')

if __name__ == '__main__':
    app.run()

关键实现点：

1. 直接使用socket处理TCP连接，避免依赖
2. 手动解析HTTP请求头，实现基本的路由匹配
3. 用装饰器注册路由处理函数
4. 支持中间件链式处理

要压缩到500行内，就得砍掉高级功能，只保留核心的路由和请求响应循环。真正的xweb可能还加了模板渲染、静态文件这些，但基本原理就这么简单。

总结：用标准库造轮子挺练手的。

我可不乐意写那些兼容 python2 的代码

建议去完善 sanic ，而不是再造一个轮子