java.net

Class URI

java.lang.Object

java.net.URI

All Implemented Interfaces:

Comparable<URI>

public final class URI
extends Object
implements Comparable<URI>

A URI instance represents that defined by RFC3986, with some deviations.

At its highest level, a URI consists of:

[scheme:]scheme-specific-part [#fragment]

where # and : are literal characters, and those parts enclosed in square brackets are optional.

There are two main types of URI. An opaque URI is one which just consists of the above three parts, and is not further defined. An example of such a URI would be mailto: URI. In contrast, hierarchical URIs give further definition to the scheme-specific part, so as represent some part of a hierarchical structure.

[//authority][path] [?query]

with / and ? being literal characters. When server-based, the authority section is further subdivided into:

[user-info@]host [:port]

with @ and : as literal characters. Authority sections that are not server-based are said to be registry-based.

Hierarchical URIs can be either relative or absolute. Absolute URIs always start with a `/', while relative URIs don't specify a scheme. Opaque URIs are always absolute.

Each part of the URI may have one of three states: undefined, empty or containing some content. The former two of these are represented by null and the empty string in Java, respectively. The scheme-specific part may never be undefined. It also follows from this that the path sub-part may also not be undefined, so as to ensure the former.

Character Escaping and Quoting

The characters that can be used within a valid URI are restricted. There are two main classes of characters which can't be used as is within the URI:

1. Characters outside the US-ASCII character set. These have to be escaped in order to create an RFC-compliant URI; this means replacing the character with the appropriate hexadecimal value, preceded by a `%'.
2. Illegal characters (e.g. space characters, control characters) are quoted, which results in them being encoded in the same way as non-US-ASCII characters.

The set of valid characters differs depending on the section of the URI:

• Scheme: Must be an alphanumeric, `-', `.' or '+'.
• Authority:Composed of the username, host, port, `@' and `:'.
• Username: Allows unreserved or percent-encoded characters, sub-delimiters and `:'.
• Host: Allows unreserved or percent-encoded characters, sub-delimiters and square brackets (`[' and `]') for IPv6 addresses.
• Port: Digits only.
• Path: Allows the path characters and `/'.
• Query: Allows the path characters, `?' and '/'.
• Fragment: Allows the path characters, `?' and '/'.

These definitions reference the following sets of characters:

• Unreserved characters: The alphanumerics plus `-', `.', `_', and `~'.
• Sub-delimiters: `!', `$', `&', `(', `)', `*', `+', `,', `;', `=' and the single-quote itself.
• Path characters: Unreserved and percent-encoded characters and the sub-delimiters along with `@' and `:'.

The constructors and accessor methods allow the use and retrieval of URI components which contain non-US-ASCII characters directly. They are only escaped when the toASCIIString() method is used. In contrast, illegal characters are always quoted, with the exception of the return values of the non-raw accessors.

Since:

1.4

Author:

Ito Kazumitsu (ito.kazumitsu@hitachi-cable.co.jp), Dalibor Topic (robilad@kaffe.org), Michael Koch (konqueror@gmx.de), Andrew John Hughes (gnu_andrew@member.fsf.org)

Constructor Summary

Constructors

Constructor and Description
URI(String str) Creates an URI from the given string
URI(String scheme, String ssp, String fragment) Create an URI from the given components
URI(String scheme, String userInfo, String host, int port, String path, String query, String fragment) Create an URI from the given components
URI(String scheme, String host, String path, String fragment) Create an URI from the given components
URI(String scheme, String authority, String path, String query, String fragment) Create an URI from the given components

Method Summary

Modifier and Type	Method and Description
int	compareTo(URI uri) Compare the URI with another URI.
static URI	create(String str) Create an URI from the given string
boolean	equals(Object obj) Compares the URI with the given object for equality.
String	getAuthority() Returns the decoded authority part of this URI
String	getFragment() Returns the fragment of the URI
String	getHost() Returns the hostname of the URI
String	getPath() Returns the path of the URI
int	getPort() Returns the port number of the URI
String	getQuery() Returns the query of the URI
String	getRawAuthority() Returns the raw authority part of this URI
String	getRawFragment() Return the raw fragment part of this URI
String	getRawPath() Returns the raw path part of this URI
String	getRawQuery() Returns the raw query part of this URI
String	getRawSchemeSpecificPart() Returns the raw scheme specific part of this URI.
String	getRawUserInfo() Returns the raw user info part of this URI
String	getScheme() Returns the scheme of the URI
String	getSchemeSpecificPart() Returns the decoded scheme specific part of this URI.
String	getUserInfo() Returns the decoded user info part of this URI
int	hashCode() Computes the hashcode of the URI
boolean	isAbsolute() Tells whether this URI is absolute or not
boolean	isOpaque() Tell whether this URI is opaque or not
URI	normalize() Returns a normalized version of the URI.
URI	relativize(URI uri) Relativizes the given URI against this URI.
URI	resolve(String str) Resolves the given URI string against this URI
URI	resolve(URI uri) Resolves the given URI against this URI
String	toASCIIString() Returns the URI as US-ASCII string.
String	toString() Returns the URI as a String.

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

URI

public URI(String str)
    throws URISyntaxException

Creates an URI from the given string

Parameters:

str - The string to create the URI from

Throws:

URISyntaxException - If the given string violates RFC 2396

NullPointerException - If str is null

URI

public URI(String scheme,
           String ssp,
           String fragment)
    throws URISyntaxException

Create an URI from the given components

Parameters:

scheme - The scheme name

ssp - The scheme specific part

fragment - The fragment

Throws:

URISyntaxException - If the given string violates RFC 2396

URI

public URI(String scheme,
           String userInfo,
           String host,
           int port,
           String path,
           String query,
           String fragment)
    throws URISyntaxException

Create an URI from the given components

Parameters:

scheme - The scheme name

userInfo - The username and authorization info

host - The hostname

port - The port number

path - The path

query - The query

fragment - The fragment

Throws:

URISyntaxException - If the given string violates RFC 2396

URI

public URI(String scheme,
           String host,
           String path,
           String fragment)
    throws URISyntaxException

Create an URI from the given components

Parameters:

scheme - The scheme name

host - The hostname

path - The path

fragment - The fragment

Throws:

URISyntaxException - If the given string violates RFC 2396

URI

public URI(String scheme,
           String authority,
           String path,
           String query,
           String fragment)
    throws URISyntaxException

Create an URI from the given components

Parameters:

scheme - The scheme name

authority - The authority

path - The apth

query - The query

fragment - The fragment

Throws:

URISyntaxException - If the given string violates RFC 2396

Method Detail

compareTo

public int compareTo(URI uri)
              throws ClassCastException

Compare the URI with another URI. Undefined components are taken to be less than any other component. The following criteria are observed:

• Two URIs with different schemes are compared according to their scheme, regardless of case.
• A hierarchical URI is less than an opaque URI with the same scheme.
• For opaque URIs:
• URIs with differing scheme-specific parts are ordered according to the ordering of the scheme-specific part.
• URIs with the same scheme-specific part are ordered by the raw fragment.
• For hierarchical URIs:
• URIs are ordered according to their raw authority sections, if they are unequal.
• For registry-based authorities:
• they are ordered according to the ordering of the authority component.
• For server-based authorities:
• URIs are ordered according to the raw user information.
• URIs with the same user information are ordered by the host, ignoring case.
• URIs with the same host are ordered by the port.
• URIs with the same authority section are ordered by the raw path.
• URIs with the same path are ordered by their raw query.
• URIs with the same query are ordered by their raw fragments.

Specified by:

compareTo in interface Comparable<URI>

Parameters:

uri - The other URI to compare this URI with

Returns:

a negative integer, zero or a positive integer depending on whether this URI is less than, equal to or greater than that supplied, respectively.

Throws:

ClassCastException

create

public static URI create(String str)

Create an URI from the given string

Parameters:

str - The string to create the URI from

Throws:

IllegalArgumentException - If the given string violates RFC 2396

NullPointerException - If str is null

equals

public boolean equals(Object obj)

Compares the URI with the given object for equality. If the object is not a URI, then the method returns false. Otherwise, the following criteria are observed:

• The scheme of the URIs must either be null (undefined) in both cases, or equal, ignorant of case.
• The raw fragment of the URIs must either be null (undefined) in both cases, or equal, ignorant of case.
• Both URIs must be of the same type (opaque or hierarchial)
• For opaque URIs:
• The raw scheme-specific parts must be equal.
• For hierarchical URIs:
• The raw paths must be equal, ignorant of case.
• The raw queries are either both undefined or both equal, ignorant of case.
• The raw authority sections are either both undefined or:
• For registry-based authorities:
• they are equal.
• For server-based authorities:
• the hosts are equal, ignoring case
• the ports are equal
• the user information components are equal

Overrides:

equals in class Object

Parameters:

obj - the obj to compare the URI with.

Returns:

true if the objects are equal, according to the specification above.

getAuthority

public String getAuthority()

Returns the decoded authority part of this URI

getFragment

public String getFragment()

Returns the fragment of the URI

getHost

public String getHost()

Returns the hostname of the URI

getPath

public String getPath()

Returns the path of the URI

getPort

public int getPort()

Returns the port number of the URI

getQuery

public String getQuery()

Returns the query of the URI

getRawAuthority

public String getRawAuthority()

Returns the raw authority part of this URI

getRawFragment

public String getRawFragment()

Return the raw fragment part of this URI

getRawPath

public String getRawPath()

Returns the raw path part of this URI

getRawQuery

public String getRawQuery()

Returns the raw query part of this URI

getRawSchemeSpecificPart

public String getRawSchemeSpecificPart()

Returns the raw scheme specific part of this URI. The scheme-specific part is never undefined, though it may be empty

getRawUserInfo

public String getRawUserInfo()

Returns the raw user info part of this URI

getScheme

public String getScheme()

Returns the scheme of the URI

getSchemeSpecificPart

public String getSchemeSpecificPart()

Returns the decoded scheme specific part of this URI.

getUserInfo

public String getUserInfo()

Returns the decoded user info part of this URI

hashCode

public int hashCode()

Computes the hashcode of the URI

Overrides:

hashCode in class Object

isAbsolute

public boolean isAbsolute()

Tells whether this URI is absolute or not

isOpaque

public boolean isOpaque()

Tell whether this URI is opaque or not

normalize

public URI normalize()

Returns a normalized version of the URI. If the URI is opaque, or its path is already in normal form, then this URI is simply returned. Otherwise, the following transformation of the path element takes place:

1. All `.' segments are removed.
2. Each `..' segment which can be paired with a prior non-`..' segment is removed along with the preceding segment.
3. A `.' segment is added to the front if the first segment contains a colon (`:'). This is a deviation from the RFC, which prevents confusion between the path and the scheme.

The resulting URI will be free of `.' and `..' segments, barring those that were prepended or which couldn't be paired, respectively.

Returns:

the normalized URI.

relativize

public URI relativize(URI uri)

Relativizes the given URI against this URI. The following algorithm is used:

• If either URI is opaque, the given URI is returned.
• If the schemes of the URIs differ, the given URI is returned.
• If the authority components of the URIs differ, then the given URI is returned.
• If the path of this URI is not a prefix of the supplied URI, then the given URI is returned.
• If all the above conditions hold, a new URI is created using the query and fragment components of the given URI, along with a path computed by removing the path of this URI from the start of the path of the supplied URI.

Parameters:

uri - the URI to relativize agsint this URI

Returns:

the resulting URI

Throws:

NullPointerException - if the uri is null

resolve

public URI resolve(String str)
            throws IllegalArgumentException

Resolves the given URI string against this URI

Parameters:

str - The URI as string to resolve against this URI

Returns:

The resulting URI

Throws:

IllegalArgumentException - If the given URI string violates RFC 2396

NullPointerException - If uri is null

resolve

public URI resolve(URI uri)

Resolves the given URI against this URI

Parameters:

uri - The URI to resolve against this URI

Returns:

The resulting URI, or null when it couldn't be resolved for some reason.

Throws:

NullPointerException - if uri is null

toASCIIString

public String toASCIIString()

Returns the URI as US-ASCII string. This is the same as the result from toString() for URIs that don't contain any non-US-ASCII characters. Otherwise, the non-US-ASCII characters are replaced by their percent-encoded representations.

Returns:

a string representation of the URI, containing only US-ASCII characters.

toString

public String toString()

Returns the URI as a String. If the URI was created using a constructor, then this will be the same as the original input string.

Overrides:

toString in class Object

Returns:

a string representation of the URI.