Get and post are nothing more than TCP links in nature?

Warm up chapter want to master thoroughly h Some knowledge points that must be understood .

browser	Length limit
chrome（ Google ）	url The length limit exceeds 8182 Characters return the errors listed at the beginning of this article .
Microsoft Internet Explorer（IE browser ）	url The length limit is 2083（2K+53）, Beyond that limit , Then automatically cut off （ if form Submit does not work ）
firefox（ Firefox ）	url The length is limited to 65 536 character , But it works URL The maximum length is not less than 100,000 Characters .
Safari	Length limit is at least 80 000 character .
Opera browser	Of url The length is limited to 190 000 character .Opera 9 Enter... In the address field 190 000 Characters can still be edited normally .

Status Status code

Status code	explain
200	OK The request is successful , Commonly used in GET And request status
300	If the server itself already has the preferred feedback option , So in Location The URI; The browser may Location Value as the address for automatic redirection . Besides , Unless otherwise specified , Otherwise, the response is also cacheable .
301	The requested resource has been permanently moved to a new location , Be careful ： For some uses HTTP/1.0 Browser for protocol , When they send POST The request got a 301 Response , The next redirection request will be GET The way .
302	The requested resources are temporarily from different URI Response request . Because such redirection is temporary , The client should continue to send future requests to the original address . Only in Cache-Control or Expires When specified in , This response is cacheable .
400	Bad Request Syntax error in client request , Server does not understand
401	Unauthorized The customer requires the user's identity authentication
402	Payment RequIred Retain , Future use
403	Forbidden The server understands the request from the requesting client , But refused to execute the request
404	Not Found The server could not find the field according to the client's request ( Webpage ). By this code , Website
405	Method Not Allowed Method in client request is forbidden
415	For the currently requested method and requested resource , The entity submitted in the request is not a supported format in the server , So the request was rejected .
500	Internal Sarver Error Server internal error , Unable to complete request
501	Internal Implemented The server does not support the requested feature , Unable to complete request
502	Bad Gateay When a server working as a gateway or proxy attempts to execute a request , An invalid response was received from the remote server
504	Gateway Time-out Server acting as gateway or proxy , Get the request from the remote server in case of crisis
505	HTTPVersion not supprted The server does not support the requested HTTP Version of protocol , Unable to complete processing

There's no time to explain. Go straight to the hard goods ~~~

When we conduct joint debugging between the company and the back-end ,POST and GET This is our most commonly used request method .

But you really know POST and GET Request ？

	GET	POST
Record the cache	Requested parameters / The record will be retained by the browser ,GET It is harmless when the browser is backout	POST It's not saved, it's safer , Back off POST The request will be made again
Memory limit	because GET The request parameters will be in URL On display , It also says URL There are certain restrictions , So it will also affect GET It's a kind of reference	POST Requests are theoretically unlimited , It is mainly restricted by the background server , For example Tomcat Next cancel POST Size limit （Tomcat Default 2M）
Security	GET The request mode message cannot contain entity content ,, therefore GET When requesting, you can expose the parameters in URL above , If some private data is not secure enough	POST Request we can use Form Form method and JSON Pass on the reference
Bookmark collection	Can collect	Will not be collected
visibility	Parameters can be visible to everyone	Will not be shown in URL in
beautiful	GET If there are too many request parameters, it will be messy and difficult to understand	POST You can customize format fields and other information to make it easier to read
Parameter type	GET We only accept ASCII character	and POST There is no limit to .

high energy alert summary Please note that please pick up the paper towel ~~~

HTTP/HTTPS The agreement is based on IP/TCP, and POST and GET So is the bottom floor TCP/IP, You could say GET and POST All are TCP link , and GET and POST Everything you can do is the same , Do you want to GET add Request Body and POST close URL Parameters are technically feasible ~

summary :

• GET And POST Each has its own semantics , You can't mix them .
• GET Will produce a TCP Data packets ,POST Produce two TCP Data packets
• about GET Mode request , The browser will http Request and Data Send it together , Server response 200( Status code )
• and POST, Browser sends back first Header, Server response 100 Content, Browser sending Data, Server response 200( Status code ). Not all browsers will POST Send two packets in ,Firefox Just send it once .
• According to research , In a good network environment , The difference between the time to send a packet and the time to send two packets is negligible . And in the case of bad network environment , The two packages TCP On verifying packet integrity , It has great advantages .