Python网络爬虫

目录
项目一 Python 基础认知 ····················································································.1
任务一 Python 概述 ·······································································································.1
一、Python 简介 ······································································································.1
二、安装Python ······································································································.2
三、安装PyCharm ···································································································.6
四、Python 语法规范 ·······························································································.11
任务二 Python 命令的组成 ·····························································································.13
一、基本符号 ·········································································································.14
二、常量与变量 ······································································································.16
三、数据类型 ·········································································································.19
四、功能符号 ·········································································································.24
任务三 程序结构 ·········································································································.26
一、表达式语句 ······································································································.26
二、顺序结构 ·········································································································.27
三、选择结构 ·········································································································.28
四、循环结构 ·········································································································.30
五、条件表达式 ······································································································.31
六、程序的流程控制 ································································································.32
项目实战 ·····················································································································.33
实战 输出百度网址 ································································································.33
项目二 网络爬虫基础认知 ················································································.35
任务一 网络爬虫概述 ···································································································.35
一、网络爬虫的基本原理 ··························································································.36
二、网络爬虫系统框架 ·····························································································.37
三、爬行策略 ·········································································································.37
四、网络爬虫的分类 ································································································.38
五、开源网络爬虫框架/项目 ······················································································.39
任务二 HTTP ·············································································································.41
一、HTTP 的工作原理 ·····························································································.41
二、Urllib 模块库 ···································································································.42
三、URL 定义 ·······································································································.43
四、URL 编码设置 ·································································································.47
任务三 网页请求过程 ···································································································.50
一、发送请求报文 ··································································································.51
二、返回响应 ········································································································.52
三、HTTP 消息 ··········································································