Optional values and functions of the itemized contenttype parameter in the request header

Count in detail contentType Optional values and functions of parameters in the request header

There was an article that said http request-header Introduction of some parameters in , It's rough , I didn't say content-type, Today, let's take a look at this humble , But the important attribute .

Want to know what is Content-Type, First of all, understand what is Internet Media Type.Internet Media Type That is, the type of Internet media , It's also called MIME type , Use a two-part identifier to determine a type . stay HTTP In the protocol header , Use Content-Type To represent the media type information in the specific request , That is to say ,Content-Type yes Internet Media Type stay HTTP Nickname in the agreement .

Content-Type The format of

type/subtype(;parameter)? type

It's on it Content-Type The format of , It can be disassembled into three parts , They are the main types （type）、 subtypes （subtype） And parameters （parameter）.

Main type （type）

The main type can be any string , such as text. If it is * The number represents all types .

subtypes （subtype）

The subtype can be any string , such as html. If it is * The number represents all types .

Parameters （parameter）

Parameters are optional , Can be in Content-Type Add some special parameters to , such as Accept Parameters of request header , Common ones are used to set character encoding charset Parameters .

Content-Type: text/html;charset:utf-8;

The data type passed from the front end to the back end , Generally, there are files and pure data .

Word of the file , We use forms to upload . Data words , We use json Format upload . This is the most serious way to deal with it . Of course, there are browser native forms , Use XML Data transmission as encoding format .

Follow the order introduced in the previous paragraph , Let's introduce the corresponding parameters

1、multipart/form-data

It will process the data of the form into a message , Label as unit , Separate with separator . You can upload both key value pairs and files . Of course , Because it can append Multiple key values , So you can also upload multiple files

2、application/json

The transmission is json Formatted data , It's quite convenient to use

3、application/x-www-form-urlencoded

Browser native form Forms . Data submitted as per key1=val1&key2=val2 The way to code ,key and val It's all going on URL transcoding . Most server-side languages have good support for this approach .

4、text/xml

Compared with JSON,XML Not better for data exchange , It contains too much packaging , And it doesn't match the data model of most programming languages , To the surprise of most programmers ,XML It's data oriented ,JSON It's object-oriented and structured , The latter will give programmers a more cordial feeling .
Summary ：

Choose different content-type Property value , It will let the browser convert the data in a specific format and send it to the background , At the same time, inform the server of the parameter type . If the selection is improper , The backstage partner can't receive data