Difference between URI and URL

URI Uniform resource identifiers ： Used to identify Web Any type of resource accessible on （HTML, video ·, Audio , Program ）

For example, there is a need to find a book in a city library （ Books are also resources ）： The location of this book is “ Building the fourth floor of the third bookshelf in the literature area of luhaowu library 《XXX》”

“《XXX》” be relative to “ The fourth floor of the third bookshelf in the literature area “ It's an identifier
“ On the fourth floor of the third bookshelf in the literature section 《XXX》“ be relative to “ Build the road good things library ” It's an identifier

The unique resource identifier is not fixed , It's relative . Its main function is to distinguish it from other resources .

URI It's made up of three parts ：

1： The naming mechanism for accessing resources ： such as ：com（ company ）、gov（ government organs ）、edu（ educational services ）

2： Host name of the resource （ The computer IP Number ）

3： Identify the path of the resource itself

URL Uniform resource locator ： yes Internet The address of the resource , The string used to define the reference address , Used to locate the location of a resource and the protocol it uses

We visit a website on a browser , The contents of a string entered above , such as “http://www.baidu.com” It's just one. URL

URL The protocol is described in , Used to retrieve resources and resource names . If it is web Resources on , The protocol used is http perhaps https. If the resource is of file type , Then the protocol used is ftp. If the resource is mail type , The protocol used is mailto

URL It consists of seven parts :

1： The protocol used （http,ftp）

2： Location of the server （IP Number ）

3： Port number on the server （0~65535）

4： Path where the resource is located

5： Parameters （ Access the parameters of the resource ）

6： fragment （ issue http Server data ）

URI And URL The difference between ：

1：URI yes URL A parent class of ,URL yes URI A subset of .

2： It's not an inclusion relationship , But similar to java An inheritance relationship in （ Inherit ： The subclass has the properties and methods defined by the parent class within the allowed range , And can be extended on this basis ）