第一步：打開瀏覽器，按鍵盤上的F12，出現如下界面：
第二步：點擊 Network， 點擊 docs 。
第三步：地址欄輸入baidu.com，按回車。
第四步：會看到這裏出現一個地址。
第五步：點擊就可以查看它的 headers（請求頭和響應頭）。
General：
Request URL: https://www.baidu.com/
Request Method: GET
Status Code: 200 OK
Remote Address: 14.215.177.38:443
Referrer Policy: no-referrer-when-downgrade
響應頭：（Response Headers）
HTTP/1.1 200 OK
Bdpagetype: 1
Bdqid: 0x8b78baf70015fe36
Cache-Control: private
Connection: keep-alive
Content-Encoding: gzip
Content-Type: text/html;charset=utf-8
Date: Fri, 20 Mar 2020 07:30:49 GMT
Expires: Fri, 20 Mar 2020 07:30:42 GMT
Server: BWS/1.1
Set-Cookie: BDSVRTM=0; path=/
Set-Cookie: BD_HOME=1; path=/
Set-Cookie: H_PS_PSSID=30972_1437_21113_30824_26350_30717; path=/; domain=.baidu.com
Strict-Transport-Security: max-age=172800
Traceid: 1584689449025470209010049988138498391606
X-Ua-Compatible: IE=Edge,chrome=1
Transfer-Encoding: chunked
請求頭：（Request Headers）
GET / HTTP/1.1
Host: www.baidu.com
Connection: keep-alive
Pragma: no-cache
Cache-Control: no-cache
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3987.149 Safari/537.36
Sec-Fetch-Dest: document
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
Sec-Fetch-Site: none
Sec-Fetch-Mode: navigate
Sec-Fetch-User: ?1
Accept-Encoding: gzip, deflate, br
Accept-Language: zh-CN,zh;q=0.9
Cookie: BAIDUID=CECCC47CE6725B83E83BDCAEFA2428F1:FG=1; BIDUPSID=CECCC47CE6725B83E83BDCAEFA2428F1; PSTM=1578380042; BD_UPN=12314753; COOKIE_SESSION=245279_0_9_5_7_38_0_0_5_6_9_3_490339_0_13_0_1584411493_0_1584411480%7C9%230_0_1584411480%7C1; BDORZ=B490B5EBF6F3CD402E515D22BCDA1598; H_PS_645EC=9daeWiR%2BzZNg1uwDBXRDQuFDlsQ9KA%2FjV%2B%2FGFTgoQz85jexVkwyN7SHpUKY