Python Web Development: A Quick Start with the Lightweight Flask Framework
This article introduces the basic content of Flask, a lightweight Python web framework, including: **Definition and Features**: Flask is a lightweight and flexible Python framework that encapsulates repetitive tasks (such as HTTP handling and route management). It has a low learning curve, strong scalability, and is suitable for quickly developing small websites or APIs. **Environment Setup**: Install it via `pip install flask` and verify the version with `flask --version`. **First Application**: Create `app.py` to instantiate Flask, define the root route with `@app.route('/')`, and start the server with `app.run(debug=True)`. Accessing `http://127.0.0.1:5000` will display "Hello, Flask!". **Routes and View Functions**: Support basic routes (e.g., `/about`) and dynamic parameters (e.g., `/user/<username>`). Parameter types include integers, paths, etc. (e.g., `/post/<int:post_id>`). **Templates and Static Files**: Use the Jinja2 template engine for dynamic rendering of variables, loops, and conditions (in the `templates` folder); static resources (CSS/JS) are placed in the `static` folder, accessed via `url_for('static', filename='...')`.
Read MoreHTTP Requests and Responses: Fundamental Core Concepts in Python Web Development
In Python web development, HTTP is the core for communication between the client (e.g., a browser) and the server, based on the "request-response" mechanism. The client generates an HTTP request, which includes methods (GET/POST, etc.), URLs, header information (e.g., User-Agent, Cookie), and a request body (POST data). After processing, the server returns an HTTP response, which contains a status code (e.g., 200 for success, 404 for not found), response headers (e.g., Content-Type), and a response body (web pages/data). The process is: client sends a request → server parses and processes it → returns a response → client renders the response (e.g., HTML to render a web page). Python frameworks (e.g., Flask) simplify this process. In the example, Flask uses `request` to access the request and `return` to directly send back the response content. Understanding this mechanism is fundamental to web development and lays the foundation for advanced studies such as HTTPS and Cookies.
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