Absolute urls, relative urls, and…?

问题

I am writing some documentation and I have a little vocabulary problem:

http://www.example.com/en/public/img/logo.gif is called an \"absolute\" url, right?
../../public/img/logo.gif is called a \"relative\" url, right?
so how do you call this: /en/public/img/logo.gif ?

Is it also considered an \"absolute url\", although without the protocol and domain parts?

Or is it considered a relative url, but relative to the root of the domain?

I googled a bit and some people categorize this as absolute, and others as relative.

What should I call it? A \"semi-absolute url\"? Or \"semi-relative\"? Is there another word?

回答1:

Here are the URL components:

http://www.example.com/en/public/img/logo.gif
\__/   \_____________/\_____________________/
 #1     #2             #3

scheme/protocol
host
path

A URL is called an absolute URL if it begins with the scheme and scheme specific part (here // after http:). Anything else is a relative URL.

A URL path is called an absolute URL path if it begins with a /. Any other URL path is called a relative URL path.

Thus:

http://www.example.com/en/public/img/logo.gif is a absolute URL,
../../public/img/logo.gif is a relative URL with a relative URL path and
/en/public/img/logo.gif is a relative URL with an absolute URL path.

Note: The current definition of URI (RFC 3986) is different from the old URL definition (RFC 1738 and RFC 1808).

The three examples with URI terms:

http://www.example.com/en/public/img/logo.gif is a URI,
../../public/img/logo.gif is a relative reference with just a relative path and
/en/public/img/logo.gif is a relative reference with just an absolute path.

回答2:

It is sometimes called a virtual url, for example in SSI:

<!--#include virtual = "/lib/functions.js" -->

回答3:

From the Microsoft's documentation about Absolute and Relative URLs

A URL specifies the location of a target stored on a local or networked computer. The target can be a file, directory, HTML page, image, program, and so on.

An absolute URL contains all the information necessary to locate a resource.

A relative URL locates a resource using an absolute URL as a starting point. In effect, the "complete URL" of the target is specified by concatenating the absolute and relative URLs.

An absolute URL uses the following format: scheme://server/path/resource

A relative URL typically consists only of the path, and optionally, the resource, but no scheme or server. The following tables define the individual parts of the complete URL format.

scheme - Specifies how the resource is to be accessed.

server - Specifies the name of the computer where the resource is located.

path - Specifies the sequence of directories leading to the target. If resource is omitted, the target is the last directory in path.

resource - If included, resource is the target, and is typically the name of a file. It may be a simple file, containing a single binary stream of bytes, or a structured document, containing one or more storages and binary streams of bytes.

回答4:

Keep in mind just how many segments of the URL can be omited, making them relative (note: its all of them, just about). These are all valid URLs:

http://example.com/bar?baz
?qoo=qalue
/bar2
dat/sly
//auth.example.com (most people are surprised by this one! Will use http or https, depending on the current resource)
#anchor

回答5:

I have seen it called a root relative URL.

回答6:

Facebook would call /en/public/img/logo.gif a protocol-relative URL (see their batch API).

来源：https://stackoverflow.com/questions/904046/absolute-urls-relative-urls-and

标签

url

terminology

relative-url