Interpretation of URL structure

URL(Uniform Resource Locator) Uniform resource locator , It is composed of a string of simple text characters . A standard URL Corresponding to a specific resource of the server ( Such as HTML page , A picture, etc ).

Scheme:

//

Login:[email protected]

Address

:port

/path/to/resource

?query_string

#fragment

According to the complete URL Structure definition of , Divided into the above 8 Parts of , Each part has certain characteristics , And some parts are necessary , Some are optional . The definition of standards is quite different from the implementation of these standards by browsers .

Scheme part ： The partial .

      The protocol name consists of a string Case insensitive letters form , With  :  As an end sign . The protocol represents the protocol that needs to be used to obtain the resource . Such as HTTP、HTTPS etc. . The browser will support some additional protocols , Such as data: and javascript: etc. .

// part ： Hierarchy URL Signs

      Basically every URL Will contain this symbol , Is constant ; It can be understood as a symbol that separates the protocol from the following information . Follow the instructions in the book , One advantage is Web Applications do not need to pay attention to the specific implementation of a protocol , Just focus on ’//’ Just point to the address after the symbol .

      But there are also non hierarchical URL： for example ,mailto: agreement . When using

mailto:[email protected]?.... When , The URL Will be able to deliver to the default mail client without additional parsing .

Login:[email protected] part ： Authentication

      In fact, we see less of this piece of information , This is an optional part , General agreement (http\https And so on ) Will use the default anonymous form for data acquisition , This section uses @ As the closing symbol of this part .

Address part ： Server address

      This is a key part , It's about which server you need to get resources from . What we see more is that this part is based on domain names (htc.org) In the form of , And Ipv4(220.181.111.188) Address rendering for . Of course, it can also be Ipv6 In the form of .

      According to the standard description, this part can only be used ： Numbers 、“.”、“-” form . But the browser will support more characters .

Port part ： Server port

      Here is the network port ,16 position , Therefore, it can be [0~2^16), The port here is not a physical port , It's a logical port ; As long as it is for data transmission when processing multiple processes , Ensure that the data in each process will not be disordered , It can be transmitted to the set in the corresponding process （ Reference resources ： port _ Baidu Encyclopedia ）

Different network protocols have their own specific port numbers ： Such as http 80

/path/to/resource： File path

      aforementioned URL It points to a unique resource , This point is to the full path of the resource （ That is, the storage location ）, It's usually used /  Hierarchical description .

?query_string： Query string

      The query string here is used to pass parameters to the server . But the standard does not have particularly strict provisions on this part . This part is based on  ?  Start as a sign , Now the general usage is similar to the following form ,?name=hello&id=5&… , And this usage is also called server-side language （ Such as PHP etc. ） Supported by the , Such as PHP The method to get the query value is ：

$_GET['id']
$_POST['id']

#fragment: fragment ID

      This part is similar to the above ? The essential difference between the following form information is that this part of the content will not be delivered to the server . Generally used for page anchors . There is a button to return to the top in the lower right foot of our common website , It is generally implemented with .