> [TOC]

# 1、浏览器发起HTTP请求的典型场景

![image-20220806144233998](assets/image-20220806144233998.png)

![image-20220806144244409](assets/image-20220806144244409.png)

# 2、HTTP协议

## 2.1、定义

​		一种无状态的、应用层的、以请求/应答方式运行的协议，它使用可扩展的语义和自描述消息格式，与基于网络的超文本信息系统灵活的互动

## 2.2、基于ABNF定义的HTTP消息

![image-20220806145420006](assets/image-20220806145420006.png)

![image-20220806145434440](assets/image-20220806145434440.png)

![image-20220807223707927](assets/image-20220807223707927.png)

![image-20220806145915215](assets/image-20220806145915215.png)

## 2.3、网络为什么要分层？

**OSI三次模型**

![image-20220806151123689](assets/image-20220806151123689.png)

* 应用层：HTTP，P2P实际所在的层次，解决业务问题
* 表示层：负责将网络消息转换为应用层可以读取的消息
* 会话层：建立session，建立会话和管理
* 传输层：进程之间的通讯，报文可达。TCP
* 网络层：广域网，IP协议
* 数据链路层：局域网中，二层路由器
* 物理层：物理介质。交换机

**TCP/IP协议**

![image-20220806151624737](assets/image-20220806151624737.png)

## 2.4、HTTP解决了什么问题？

![image-20220806154100285](assets/image-20220806154100285.png)

## 2.5、HTTP设计遵循的web架构原则

![image-20220806154143306](assets/image-20220806154143306.png)

![image-20220806155015178](assets/image-20220806155015178.png)

* a路径：代理+反向代理+服务器
* b路径：直接到达服务器
* c路径：代理+服务器

# 3、五类架构风格推到出HTTP的REST架构

## 3.1、架构风格

![image-20220806155335413](assets/image-20220806155335413.png)

### 3.1.1、数据流风格

![image-20220806155456202](assets/image-20220806155456202.png)

### 3.1.2、复制风格

![image-20220806162104407](assets/image-20220806162104407.png)

### 3.1.3、分层风格

![image-20220806162157828](assets/image-20220806162157828.png)

![image-20220806162335706](assets/image-20220806162335706.png)

### 3.1.4、移动代码风格

![image-20220806162518481](assets/image-20220806162518481.png)

### 3.1.5、点对点风格

![image-20220806162745010](assets/image-20220806162745010.png)

## 3.2、风格演化（LCODC$SS）

![image-20220806163012278](assets/image-20220806163012278.png)

# 4、URI的基本格式以及与URL的区别

## 4.1、什么是URI

![image-20220806202916858](assets/image-20220806202916858.png)

![image-20220806203014182](assets/image-20220806203014182.png)

## 4.2、URI的组成

![image-20220806204504063](assets/image-20220806204504063.png)

## 4.3、URI的格式

![image-20220806204606335](assets/image-20220806204606335.png)

![image-20220806204631447](assets/image-20220806204631447.png)

![image-20220806204759320](assets/image-20220806204759320.png)

## 4.4、相对URI

![image-20220806204828999](assets/image-20220806204828999.png)

## 4.5、URI编码

### 4.5.1、为什么要进行URI编码？

![image-20220806204928022](assets/image-20220806204928022.png)

![image-20220806205027008](assets/image-20220806205027008.png)

### 4.5.2、编码方式

![image-20220806205107975](assets/image-20220806205107975.png)

# 5、HTTP请求行

## 5.1、请求格式

![image-20220806205257838](assets/image-20220806205257838.png)

![image-20220806205305103](assets/image-20220806205305103.png)

![image-20220806205358329](assets/image-20220806205358329.png)

## 5.2、常见方法

![image-20220806205426999](assets/image-20220806205426999.png)

![image-20220806205908230](assets/image-20220806205908230.png)

# 6、HTTP响应

## 6.1、HTTP响应行

![image-20220806210436558](assets/image-20220806210436558.png)

## 6.2、HTTP响应码

![image-20220806210459359](assets/image-20220806210459359.png)

![image-20220806210505853](assets/image-20220806210505853.png)

![image-20220806210512198](assets/image-20220806210512198.png)

![image-20220806210521437](assets/image-20220806210521437.png)

![image-20220806210530673](assets/image-20220806210530673.png)

![image-20220806210540664](assets/image-20220806210540664.png)

![image-20220806210549017](assets/image-20220806210549017.png)

![image-20220806210558017](assets/image-20220806210558017.png)

![image-20220806210603899](assets/image-20220806210603899.png)

![image-20220806210609644](assets/image-20220806210609644.png)

![image-20220806210615289](assets/image-20220806210615289.png)

# 7、长连接与短连接

## 7.1、简单的短连接

![image-20220806213308581](assets/image-20220806213308581.png)

![image-20220806213250798](assets/image-20220806213250798.png)

## 7.2、持久的长连接

![image-20220806213257668](assets/image-20220806213257668.png)

## 7.3、connect注意事项

![image-20220806213614563](assets/image-20220806213614563.png)

![image-20220806213640171](assets/image-20220806213640171.png)

# 8、HOST头部

![image-20220807193047285](assets/image-20220807193047285.png)

## 8.1、如何传递IP地址到服务器？

![image-20220807193318110](assets/image-20220807193318110.png)

![image-20220807193522235](assets/image-20220807193522235.png)

# 9、请求与响应的上下文

## 9.1、User-Agent

![image-20220807193726574](assets/image-20220807193726574.png)

## 9.2、Referer

![image-20220807194722974](assets/image-20220807194722974.png)

## 9.3、From

![image-20220807194844430](assets/image-20220807194844430.png)

## 9.4、Server

![image-20220807194911574](assets/image-20220807194911574.png)

## 9.5、Allow 与Accept-Ranges

![image-20220807194934580](assets/image-20220807194934580.png)

# 10、内容协商

## 10.1、定义

![image-20220807195159024](assets/image-20220807195159024.png)

## 10.2、分类

![image-20220807195148845](assets/image-20220807195148845.png)

### 10.2.1、Proactive

![image-20220807195302609](assets/image-20220807195302609.png)

### 10.2.2、Reactive

![image-20220807195423426](assets/image-20220807195423426.png)

## 10.3、协商要素

![image-20220807195541807](assets/image-20220807195541807.png)

![image-20220807195553855](assets/image-20220807195553855.png)

![image-20220807195823150](assets/image-20220807195823150.png)

# 11、HTTP包体的传输方式

## 11.1、定义

![image-20220807200050541](assets/image-20220807200050541.png)

## 11.2、传输方式

### 11.2.1、方式一

![image-20220807200118145](assets/image-20220807200118145.png)

![image-20220807202245823](assets/image-20220807202245823.png)

### 11.2.2、方式二

![image-20220807200139017](assets/image-20220807200139017.png)

![image-20220807201551020](assets/image-20220807201551020.png)

![image-20220807202120503](assets/image-20220807202120503.png)

## 11.3、其他头部

![image-20220807202328521](assets/image-20220807202328521.png)

# 12、form表单提交协议

## 12.1、定义

![image-20220807202536077](assets/image-20220807202536077.png)

## 12.2、关键属性

![image-20220807220610447](assets/image-20220807220610447.png)

![image-20220807221107421](assets/image-20220807221107421.png)

![image-20220807221140643](assets/image-20220807221140643.png)

# 13、断点续传与多线程下载

## 13.1、实际场景

![image-20220807221816578](assets/image-20220807221816578.png)

## 13.2、HHTP Range规范

![image-20220807221953545](assets/image-20220807221953545.png)

![image-20220807222000149](assets/image-20220807222000149.png)

![image-20220807222012403](assets/image-20220807222012403.png)

> 若if-Range头部校验不通过，会返回0-end（end表示此次发送的结尾）这么多的数据
>
> 与if-match头部返回两次性能优化

## 13.3、服务器响应

![image-20220807222410199](assets/image-20220807222410199.png)

![image-20220807222417961](assets/image-20220807222417961.png)

![image-20220807223049652](assets/image-20220807223049652.png)

# 14、cookie的格式和约束

## 14.1、定义

![image-20220807223443923](assets/image-20220807223443923.png)

![image-20220807223729500](assets/image-20220807223729500.png)

![image-20220807223803887](assets/image-20220807223803887.png)

## 14.2、问题与限制

![image-20220807224009675](assets/image-20220807224009675.png)

![image-20220807224017199](assets/image-20220807224017199.png)

# 15、session

## 15.1、cookie与session

![image-20220807224428454](assets/image-20220807224428454.png)

![image-20220807224528081](assets/image-20220807224528081.png)

## 15.2、三方cookie

![image-20220807224812200](assets/image-20220807224812200.png)

# 16、浏览器的同源策略

## 16.1、为什么需要？

![image-20220807225300099](assets/image-20220807225300099.png)

![image-20220807225411779](assets/image-20220807225411779.png)

![image-20220807225446382](assets/image-20220807225446382.png)

![image-20220807225638474](assets/image-20220807225638474.png)

## 16.2、定义

![image-20220807225703603](assets/image-20220807225703603.png)

![image-20220807230346243](assets/image-20220807230346243.png)

## 16.3、CSRF

![image-20220807230932801](assets/image-20220807230932801.png)

**这个方式已经被破解，攻击者可以获取你的全部cookie**

![image-20220807231012250](assets/image-20220807231012250.png)

## 16.4、CORS简介

![image-20220808205400843](assets/image-20220808205400843.png)

![image-20220808205649293](assets/image-20220808205649293.png)

![image-20220808210506819](assets/image-20220808210506819.png)

![image-20220808210844828](assets/image-20220808210844828.png)

![image-20220808210851894](assets/image-20220808210851894.png)

# 17、条件请求

## 17.1、定义

![image-20220808211110446](assets/image-20220808211110446.png)

![image-20220808211349935](assets/image-20220808211349935.png)

## 17.2、验证

![image-20220808211457292](assets/image-20220808211457292.png)

![image-20220808211536423](assets/image-20220808211536423.png)

![image-20220808211547520](assets/image-20220808211547520.png)

![image-20220808211700742](assets/image-20220808211700742.png)

## 17.3、应用场景

### 17.3.1、缓存更新

![image-20220808211714562](assets/image-20220808211714562.png)

![image-20220808211843742](assets/image-20220808211843742.png)

### 17.3.2、增量更新

![image-20220808211853255](assets/image-20220808211853255.png)

![image-20220808211902719](assets/image-20220808211902719.png)

![image-20220808211908257](assets/image-20220808211908257.png)

![image-20220808212025760](assets/image-20220808212025760.png)

### 17.3.3、更新丢失

![image-20220808212342614](assets/image-20220808212342614.png)

![image-20220808212358728](assets/image-20220808212358728.png)

![image-20220808212410381](assets/image-20220808212410381.png)

![image-20220808212453408](assets/image-20220808212453408.png)

## 17.4、nginx模块如何条件验证

![image-20220808212552355](assets/image-20220808212552355.png)

# 18、HTTP缓存的工作原理

## 18.1、原理

![image-20220809211113345](assets/image-20220809211113345.png)

![image-20220809211144105](assets/image-20220809211144105.png)

![image-20220809211155084](assets/image-20220809211155084.png)

## 18.2、私有与共享缓存

![image-20220809211610966](assets/image-20220809211610966.png)

![image-20220809211653355](assets/image-20220809211653355.png)

## 18.3、缓存原理

![image-20220809211729845](assets/image-20220809211729845.png)

## 18.4、判断缓存是否过期

![image-20220809211845226](assets/image-20220809211845226.png)

![image-20220809212115550](assets/image-20220809212115550.png)

![image-20220809212151863](assets/image-20220809212151863.png)

## 18.5、Age 头部及 current_age 的计算

![image-20220809212244390](assets/image-20220809212244390.png)

![image-20220809212444480](assets/image-20220809212444480.png)

# 19、Cache-Control 头部

## 19.1、定义

![image-20220809212726752](assets/image-20220809212726752.png)

## 19.2、请求的含义

![image-20220809212911441](assets/image-20220809212911441.png)

## 19.3、响应的含义

![image-20220809212945172](assets/image-20220809212945172.png)

![image-20220809213116535](assets/image-20220809213116535.png)

# 20、什么样的响应会被缓存？

## 20.1、定义

![image-20220809213328323](assets/image-20220809213328323.png)

![image-20220809213537383](assets/image-20220809213537383.png)

## 20.2、使用条件

![image-20220809213601029](assets/image-20220809213601029.png)

![image-20220809213630731](assets/image-20220809213630731.png)

![image-20220809213645854](assets/image-20220809213645854.png)

## 20.3、如何缓存更新频率不同的资源

![image-20220809213823569](assets/image-20220809213823569.png)

![image-20220809213828831](assets/image-20220809213828831.png)

![image-20220809213958809](assets/image-20220809213958809.png)

![image-20220809214025329](assets/image-20220809214025329.png)

# 21、HTTP重定向

## 21.1、为什么需要 URI 重定向？

![image-20220809214131056](assets/image-20220809214131056.png)

## 21.2、重定向流程

![image-20220809214222467](assets/image-20220809214222467.png)

![image-20220809214241598](assets/image-20220809214241598.png)

## 21.3、重定向响应返回码

![image-20220809214319604](assets/image-20220809214319604.png)

![image-20220809214329100](assets/image-20220809214329100.png)

## 21.4、重定向循环

![image-20220809214753825](assets/image-20220809214753825.png)

# 22、Http Tunnel 隧道

## 22.1、目的

![image-20220811204734585](assets/image-20220811204734585.png)

## 22.2、请求行

![image-20220811205055394](assets/image-20220811205055394.png)

## 22.3、常见应用

![image-20220811205114071](assets/image-20220811205114071.png)

 ![image-20220811205128401](assets/image-20220811205128401.png)

# 23、网络爬虫

## 23.1、定义

![image-20220811205252126](assets/image-20220811205252126.png)

## 23.2、对待爬虫的态度

![image-20220811205447322](assets/image-20220811205447322.png)

![image-20220811205456536](assets/image-20220811205456536.png)

![image-20220811205505728](assets/image-20220811205505728.png)

![image-20220811205514497](assets/image-20220811205514497.png)

## 23.3、网络爬虫如何抓取数据？

![image-20220811205532682](assets/image-20220811205532682.png)

![image-20220811205626891](assets/image-20220811205626891.png)

![image-20220811205644784](assets/image-20220811205644784.png)

# 24、HTTP资源的认证

## 24.1、定义

![image-20220811211040737](assets/image-20220811211040737.png)

![image-20220811212654282](assets/image-20220811212654282.png)

## 24.2、响应

![image-20220811212738439](assets/image-20220811212738439.png)

# 25、DNS协议解析域名

## 25.1、定义

![image-20220811221104618](assets/image-20220811221104618.png)

## 25.2、结构

![image-20220811221123327](assets/image-20220811221123327.png)

![image-20220811221139774](assets/image-20220811221139774.png)

## 25.3、查询与响应

![image-20220811221236488](assets/image-20220811221236488.png)

![image-20220811221347329](assets/image-20220811221347329.png)

![image-20220811221516540](assets/image-20220811221516540.png)

![image-20220811221525905](assets/image-20220811221525905.png)