February 2024
Intermediate to advanced
212 pages
3h 1m
Chinese
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第7章 验证码处理
验证码（CAPTCHA）的全称为全自动区分计算机和人类的公开图灵测试（Completely Automated Public Turing test to tell Computersand Humans Apart）。从其全称可以看出，验证码用于测试用户是否为真实人类。一个典型的验证码由扭曲的文本组成，此时计算机程序难以解析，但人类仍然可以（希望如此）阅读。
许多网站使用验证码来防御与其网站交互的机器人程序。比如许多银行网站强制每次登录时都需要输入验证码，这就令人十分痛苦。本章将介绍如何自动化处理验证码问题，首先使用光学字符识别（Optical Character Recognition，OCR），然后使用一个验证码处理API。
在本章中，我们将会介绍如下主题。
- 验证码处理；
- 使用验证码处理服务；
- 机器学习和验证码；
- 报告错误。
7.1 注册账号
在第6章处理表单时，我们使用手工创建的账号登录网站，而忽略了创建账号这一部分，这是因为注册表单需要输入验证码，如图7.1所示。
图7.1
请注意，每次加载表单时都会显示不同的验证码图像。为了了解表单需要哪些参数，我们可以复用上一章编写的parse_form()函数。
>>> import requests
>>> REGISTER_URL = 'http://example.python-scraping.com/user/register'
>>> session = requests.Session()
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