palletsprojects.com/p/jinja/] template engine and the Werkzeug [https://www.palletsprojects.com/p/werkzeug/] WSGI toolkit. The documentation for these libraries can be found at: Jinja documentation [http://jinja Accessing Request Data Redirects and Errors About Responses Sessions Message Flashing Logging Hooking in WSGI Middleware Using Flask Extensions Deploying to a Web Server Tutorial Project Layout Application non-relational data persistence as appropriate, and take advantage of framework-agnostic tools built for WSGI, the Python web interface. Flask includes many hooks to customize its behavior. Should you need more

a full reference in the API section. Flask depends on the Jinja template engine and the Werkzeug WSGI toolkit. The documentation for these libraries can be found at: • Jinja documentation • Werkzeug non-relational data persistence as appropriate, and take advantage of framework-agnostic tools built for WSGI, the Python web interface. Flask includes many hooks to customize its behavior. Should you need more These distributions will be installed automatically when installing Flask. • Werkzeug implements WSGI, the standard Python interface between applications and servers. • Jinja is a template language that

Star 数量最多的 Python Web 框架，没有之一。 Flask 是典型的微框架，作为 Web 框架来说，它仅保留了核心功能：请求响应处理 和模板渲染。这两类功能分别由 Werkzeug（WSGI 工具库）完成和 Jinja（模板渲 染库）完成，因为 Flask 包装了这两个依赖，我们暂时不用深入了解它们。 主页 这一章的主要任务就是为我们的程序编写一个简单的主页。主页的 URL 一般就是 production WARNING: Do not use the development server in a production env ironment. Use a production WSGI server instead. * Debug mode: off * Running on http://127.0.0.1:5000/ (Press CTRL+C to quit) 现在打开浏览器，访问 如果你把上面的程序保存成其他的名字，比如 hello.py，接着执行 flask run 命 令会返回一个错误提示。这是因为 Flask 默认会假设你把程序存储在名为 app.py 或 wsgi.py 的文件中。如果你使用了其他名称，就要设置系统环境变量 FLASK_APP 来告诉 Flask 你要启动哪个程序。 Flask 通过读取这个文件对应的模块寻找要运行的程序实例，你可以把它设置成下