August 2018
Intermediate to advanced
230 pages
6h 42m
Chinese
Content preview from Flask Web开发：基于Python的Web应用开发实战（第2版）
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第 2 章
应用的基本结构
本章将带领你了解
Flask
应用各部分的作用，编写并运行第一个
Flask Web
应用。
2.1
初始化
所有
Flask
应用都必须创建一个
应用实例
。
Web
服务器使用一种名为
Web
服务器网关接口
（
WSGI
，
Web server gateway interface
，读作“
wiz-ghee
”）的协议，把接收自客户端的所有
请求都转交给这个对象处理。应用实例是 Flask 类的对象，通常由下述代码创建：
from flask import Flask
app = Flask(__name__)
Flask 类的构造函数只有一个必须指定的参数，即应用主模块或包的名称。在大多数应用
中，
Python
的 __name__ 变量就是所需的值。
传给
Flask
应用构造函数的
__name__
参数可能会让
Flask
开发新手心生困惑。
Flask
用这个参数确定应用的位置，进而找到应用中其他文件的位置，例如
图像和模板。
后文会介绍更复杂的应用初始化方式，不过对简单的应用来说，上面的代码足够了。
2.2
路由和视图函数
客户端（例如
Web
浏览器）把
请求
发送给
Web
服务器，
Web
服务器再把请求发送给
Flask
应用实例。应用实例需要知道对每个
URL
的请求要运行哪些代码，所以保存了一个
URL
7
8
｜
第
2
章
到
Python ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.