HTTP
什么是http
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HTTP：超文本传输协议，是一个简单的请求-相应协议
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超文本：图片、视频、音乐、定位
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默认端口：80
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HTTPS：以安全为目标的HTTP通道，在HTTP的基础上加入了SSL，保证了传输过程的安全性
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默认端口：443
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HTTP的两个时代：
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http1.0
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http/1.0：客户端与web服务器连接后，只能获得一个web资源，然后断开连接
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http2.0
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http/2.0：客户端与服务器连接后，可以获得多个web资源
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请求与相应
以访问百度为例
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常规
请求 URL: https://www.baidu.com/ 请求方法: GET 状态代码: 200 OK 远程地址: 110.242.68.4:443 引用者策略: strict-origin-when-cross-origin
响应头
Bdpagetype: 2
Bdqid: 0xba83753500003c54
Cache-Control: private --- 缓存控制
Connection: keep-alive --- 连接
Content-Encoding: gzip --- 编码
Content-Type: text/html;charset=utf-8
Date: Mon, 10 Oct 2022 07:09:05 GMT
Expires: Mon, 10 Oct 2022 07:09:05 GMT
Isprivate: 1
Server: BWS/1.1
Set-Cookie: BDSVRTM=368; path=/
Set-Cookie: BD_HOME=1; path=/
Set-Cookie: H_PS_PSSID=37378_36560_37561_37357_37300_36884_37403_37404_36789_37498_26350_37489_37372_37466; path=/; domain=.baidu.com
Strict-Transport-Security: max-age=172800
Traceid: 1665385745235747149813439714583497423956
Transfer-Encoding: chunked
X-Frame-Options: sameorigin
X-Ua-Compatible: IE=Edge,chrome=1比较重要的：
Cache-Control: private --- 缓存控制 Connection: keep-alive --- 连接 Content-Encoding: gzip --- 编码 Content-Type: text/html;charset=utf-8 --- 类型
响应状态码
200：请求成功 200
3xx：请求重定向，即重新定位，
4xx：找不到资源 404
5xx：服务器代码错误 500 502：网关错误
重定向：比如微博，如果你去请求一个不存在的资源：12354568.html，它会自动给你跳转到
2F132156dfsf.html，状态码是302，即重定向
具有重定向的网站会进行重定向，不具有重定向的网站则会报出Not Found，状态码是404
请求头
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
Accept-Encoding: gzip, deflate, br
Accept-Language: zh-CN,zh;q=0.9,en;q=0.8,en-GB;q=0.7,en-US;q=0.6
Cache-Control: max-age=0
Connection: keep-alive
Cookie: BDUSS=hESUJFSjE1SUhQYVlKWGppM0U1emd6aEQ3bXA0bWgxckRYSm1RWHI3b0xYN1JpRVFBQUFBJCQAAAAAAAAAAAEAAABglJtNuf4xMTIyNQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAvSjGIL0oxiVm; BDUSS_BFESS=hESUJFSjE1SUhQYVlKWGppM0U1emd6aEQ3bXA0bWgxckRYSm1RWHI3b0xYN1JpRVFBQUFBJCQAAAAAAAAAAAEAAABglJtNuf4xMTIyNQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAvSjGIL0oxiVm; BAIDUID=210604ED9BD399558DAD689C6364778D:FG=1; BIDUPSID=210604ED9BD399558DAD689C6364778D; PSTM=1654758697; BD_UPN=12314753; newlogin=1; ispeed=1; BAIDUID_BFESS=210604ED9BD399558DAD689C6364778D:FG=1; ZFY=kPWtjQDnAB:BFaNV4diq436h8vE0ztKlQ:B4l0nVJlBYI:C; ispeed_lsm=35; delPer=0; BD_CK_SAM=1; PSINO=2; H_PS_PSSID=37378_36560_37561_37357_37300_36884_37403_37404_36789_37498_26350_37489_37372_37466; B64_BOT=1; BA_HECTOR=80ah2h2l85810g84a50l505d1hk7gtb1b; RT="z=1&dm=baidu.com&si=wkpqgm95n&ss=l92fgk8t&sl=3&tt=88a&bcn=https%3A%2F%2Ffclog.baidu.com%2Flog%2Fweirwood%3Ftype%3Dperf&ld=dp3&ul=27ye&hd=281x"; BD_HOME=1; H_PS_645EC=38a9LNYfk1nluIg7d10OwgYiy82vo6lBzGes5XFnxGPc%2B0mzGgQNZlhNNB4; sugstore=0
Host: www.baidu.com
sec-ch-ua: "Chromium";v="106", "Microsoft Edge";v="106", "Not;A=Brand";v="99"
sec-ch-ua-mobile: ?0
sec-ch-ua-platform: "Windows"
Sec-Fetch-Dest: document
Sec-Fetch-Mode: navigate
Sec-Fetch-Site: cross-site
Sec-Fetch-User: ?1
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/106.0.0.0 Safari/537.36 Edg/106.0.1370.34比较重要的：
Accept-Encoding: gzip, deflate, br Accept-Language: zh-CN,zh;q=0.9,en;q=0.8,en-GB;q=0.7,en-US;q=0.6 Cache-Control: max-age=0 Connection: keep-alive
请求方式
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GET、POST、HEAD、DELETE、PUT、TRACT
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常用的有get和post
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get：请求能够携带的参数较少，大小有限制，会在浏览器的URL地址栏显示数据内容，不安全但高效
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post：请求能够携带的参数没有限制，大小没有限制，不会在浏览器的URL地址栏显示数据内容，安全但不高效，但现在网络今非昔比，所以可以忽略两者的效率差距
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