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URI.java
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/*
* Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package java.net;
import java.io.IOException;
import java.io.InvalidObjectException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.CharsetDecoder;
import java.nio.charset.CharsetEncoder;
import java.nio.charset.CoderResult;
import java.nio.charset.CodingErrorAction;
import java.nio.charset.CharacterCodingException;
import java.text.Normalizer;
import sun.nio.cs.ThreadLocalCoders;
import java.lang.Character; // for javadoc
import java.lang.NullPointerException; // for javadoc
/**
* Represents a Uniform Resource Identifier (URI) reference.
*
* <p> Aside from some minor deviations noted below, an instance of this
* class represents a URI reference as defined by
* <a href="http://www.ietf.org/rfc/rfc2396.txt"><i>RFC 2396: Uniform
* Resource Identifiers (URI): Generic Syntax</i></a>, amended by <a
* href="http://www.ietf.org/rfc/rfc2732.txt"><i>RFC 2732: Format for
* Literal IPv6 Addresses in URLs</i></a>. The Literal IPv6 address format
* also supports scope_ids. The syntax and usage of scope_ids is described
* <a href="Inet6Address.html#scoped">here</a>.
* This class provides constructors for creating URI instances from
* their components or by parsing their string forms, methods for accessing the
* various components of an instance, and methods for normalizing, resolving,
* and relativizing URI instances. Instances of this class are immutable.
*
*
* <h3> URI syntax and components </h3>
*
* At the highest level a URI reference (hereinafter simply "URI") in string
* form has the syntax
*
* <blockquote>
* [<i>scheme</i><b>{@code :}</b>]<i>scheme-specific-part</i>[<b>{@code #}</b><i>fragment</i>]
* </blockquote>
*
* where square brackets [...] delineate optional components and the characters
* <b>{@code :}</b> and <b>{@code #}</b> stand for themselves.
*
* <p> An <i>absolute</i> URI specifies a scheme; a URI that is not absolute is
* said to be <i>relative</i>. URIs are also classified according to whether
* they are <i>opaque</i> or <i>hierarchical</i>.
*
* <p> An <i>opaque</i> URI is an absolute URI whose scheme-specific part does
* not begin with a slash character ({@code '/'}). Opaque URIs are not
* subject to further parsing. Some examples of opaque URIs are:
*
* <blockquote><table cellpadding=0 cellspacing=0 summary="layout">
* <tr><td>{@code mailto:[email protected]}<td></tr>
* <tr><td>{@code news:comp.lang.java}<td></tr>
* <tr><td>{@code urn:isbn:096139210x}</td></tr>
* </table></blockquote>
*
* <p> A <i>hierarchical</i> URI is either an absolute URI whose
* scheme-specific part begins with a slash character, or a relative URI, that
* is, a URI that does not specify a scheme. Some examples of hierarchical
* URIs are:
*
* <blockquote>
* {@code http://java.sun.com/j2se/1.3/}<br>
* {@code docs/guide/collections/designfaq.html#28}<br>
* {@code ../../../demo/jfc/SwingSet2/src/SwingSet2.java}<br>
* {@code file:///~/calendar}
* </blockquote>
*
* <p> A hierarchical URI is subject to further parsing according to the syntax
*
* <blockquote>
* [<i>scheme</i><b>{@code :}</b>][<b>{@code //}</b><i>authority</i>][<i>path</i>][<b>{@code ?}</b><i>query</i>][<b>{@code #}</b><i>fragment</i>]
* </blockquote>
*
* where the characters <b>{@code :}</b>, <b>{@code /}</b>,
* <b>{@code ?}</b>, and <b>{@code #}</b> stand for themselves. The
* scheme-specific part of a hierarchical URI consists of the characters
* between the scheme and fragment components.
*
* <p> The authority component of a hierarchical URI is, if specified, either
* <i>server-based</i> or <i>registry-based</i>. A server-based authority
* parses according to the familiar syntax
*
* <blockquote>
* [<i>user-info</i><b>{@code @}</b>]<i>host</i>[<b>{@code :}</b><i>port</i>]
* </blockquote>
*
* where the characters <b>{@code @}</b> and <b>{@code :}</b> stand for
* themselves. Nearly all URI schemes currently in use are server-based. An
* authority component that does not parse in this way is considered to be
* registry-based.
*
* <p> The path component of a hierarchical URI is itself said to be absolute
* if it begins with a slash character ({@code '/'}); otherwise it is
* relative. The path of a hierarchical URI that is either absolute or
* specifies an authority is always absolute.
*
* <p> All told, then, a URI instance has the following nine components:
*
* <blockquote><table summary="Describes the components of a URI:scheme,scheme-specific-part,authority,user-info,host,port,path,query,fragment">
* <tr><th><i>Component</i></th><th><i>Type</i></th></tr>
* <tr><td>scheme</td><td>{@code String}</td></tr>
* <tr><td>scheme-specific-part </td><td>{@code String}</td></tr>
* <tr><td>authority</td><td>{@code String}</td></tr>
* <tr><td>user-info</td><td>{@code String}</td></tr>
* <tr><td>host</td><td>{@code String}</td></tr>
* <tr><td>port</td><td>{@code int}</td></tr>
* <tr><td>path</td><td>{@code String}</td></tr>
* <tr><td>query</td><td>{@code String}</td></tr>
* <tr><td>fragment</td><td>{@code String}</td></tr>
* </table></blockquote>
*
* In a given instance any particular component is either <i>undefined</i> or
* <i>defined</i> with a distinct value. Undefined string components are
* represented by {@code null}, while undefined integer components are
* represented by {@code -1}. A string component may be defined to have the
* empty string as its value; this is not equivalent to that component being
* undefined.
*
* <p> Whether a particular component is or is not defined in an instance
* depends upon the type of the URI being represented. An absolute URI has a
* scheme component. An opaque URI has a scheme, a scheme-specific part, and
* possibly a fragment, but has no other components. A hierarchical URI always
* has a path (though it may be empty) and a scheme-specific-part (which at
* least contains the path), and may have any of the other components. If the
* authority component is present and is server-based then the host component
* will be defined and the user-information and port components may be defined.
*
*
* <h4> Operations on URI instances </h4>
*
* The key operations supported by this class are those of
* <i>normalization</i>, <i>resolution</i>, and <i>relativization</i>.
*
* <p> <i>Normalization</i> is the process of removing unnecessary {@code "."}
* and {@code ".."} segments from the path component of a hierarchical URI.
* Each {@code "."} segment is simply removed. A {@code ".."} segment is
* removed only if it is preceded by a non-{@code ".."} segment.
* Normalization has no effect upon opaque URIs.
*
* <p> <i>Resolution</i> is the process of resolving one URI against another,
* <i>base</i> URI. The resulting URI is constructed from components of both
* URIs in the manner specified by RFC 2396, taking components from the
* base URI for those not specified in the original. For hierarchical URIs,
* the path of the original is resolved against the path of the base and then
* normalized. The result, for example, of resolving
*
* <blockquote>
* {@code docs/guide/collections/designfaq.html#28}
*
* (1)
* </blockquote>
*
* against the base URI {@code http://java.sun.com/j2se/1.3/} is the result
* URI
*
* <blockquote>
* {@code https://docs.oracle.com/javase/1.3/docs/guide/collections/designfaq.html#28}
* </blockquote>
*
* Resolving the relative URI
*
* <blockquote>
* {@code ../../../demo/jfc/SwingSet2/src/SwingSet2.java} (2)
* </blockquote>
*
* against this result yields, in turn,
*
* <blockquote>
* {@code http://java.sun.com/j2se/1.3/demo/jfc/SwingSet2/src/SwingSet2.java}
* </blockquote>
*
* Resolution of both absolute and relative URIs, and of both absolute and
* relative paths in the case of hierarchical URIs, is supported. Resolving
* the URI {@code file:///~calendar} against any other URI simply yields the
* original URI, since it is absolute. Resolving the relative URI (2) above
* against the relative base URI (1) yields the normalized, but still relative,
* URI
*
* <blockquote>
* {@code demo/jfc/SwingSet2/src/SwingSet2.java}
* </blockquote>
*
* <p> <i>Relativization</i>, finally, is the inverse of resolution: For any
* two normalized URIs <i>u</i> and <i>v</i>,
*
* <blockquote>
* <i>u</i>{@code .relativize(}<i>u</i>{@code .resolve(}<i>v</i>{@code )).equals(}<i>v</i>{@code )} and<br>
* <i>u</i>{@code .resolve(}<i>u</i>{@code .relativize(}<i>v</i>{@code )).equals(}<i>v</i>{@code )} .<br>
* </blockquote>
*
* This operation is often useful when constructing a document containing URIs
* that must be made relative to the base URI of the document wherever
* possible. For example, relativizing the URI
*
* <blockquote>
* {@code https://docs.oracle.com/javase/1.3/docs/guide/index.html}
* </blockquote>
*
* against the base URI
*
* <blockquote>
* {@code http://java.sun.com/j2se/1.3}
* </blockquote>
*
* yields the relative URI {@code docs/guide/index.html}.
*
*
* <h4> Character categories </h4>
*
* RFC 2396 specifies precisely which characters are permitted in the
* various components of a URI reference. The following categories, most of
* which are taken from that specification, are used below to describe these
* constraints:
*
* <blockquote><table cellspacing=2 summary="Describes categories alpha,digit,alphanum,unreserved,punct,reserved,escaped,and other">
* <tr><th valign=top><i>alpha</i></th>
* <td>The US-ASCII alphabetic characters,
* {@code 'A'} through {@code 'Z'}
* and {@code 'a'} through {@code 'z'}</td></tr>
* <tr><th valign=top><i>digit</i></th>
* <td>The US-ASCII decimal digit characters,
* {@code '0'} through {@code '9'}</td></tr>
* <tr><th valign=top><i>alphanum</i></th>
* <td>All <i>alpha</i> and <i>digit</i> characters</td></tr>
* <tr><th valign=top><i>unreserved</i> </th>
* <td>All <i>alphanum</i> characters together with those in the string
* {@code "_-!.~'()*"}</td></tr>
* <tr><th valign=top><i>punct</i></th>
* <td>The characters in the string {@code ",;:$&+="}</td></tr>
* <tr><th valign=top><i>reserved</i></th>
* <td>All <i>punct</i> characters together with those in the string
* {@code "?/[]@"}</td></tr>
* <tr><th valign=top><i>escaped</i></th>
* <td>Escaped octets, that is, triplets consisting of the percent
* character ({@code '%'}) followed by two hexadecimal digits
* ({@code '0'}-{@code '9'}, {@code 'A'}-{@code 'F'}, and
* {@code 'a'}-{@code 'f'})</td></tr>
* <tr><th valign=top><i>other</i></th>
* <td>The Unicode characters that are not in the US-ASCII character set,
* are not control characters (according to the {@link
* java.lang.Character#isISOControl(char) Character.isISOControl}
* method), and are not space characters (according to the {@link
* java.lang.Character#isSpaceChar(char) Character.isSpaceChar}
* method) <i>(<b>Deviation from RFC 2396</b>, which is
* limited to US-ASCII)</i></td></tr>
* </table></blockquote>
*
* <p><a name="legal-chars"></a> The set of all legal URI characters consists of
* the <i>unreserved</i>, <i>reserved</i>, <i>escaped</i>, and <i>other</i>
* characters.
*
*
* <h4> Escaped octets, quotation, encoding, and decoding </h4>
*
* RFC 2396 allows escaped octets to appear in the user-info, path, query, and
* fragment components. Escaping serves two purposes in URIs:
*
* <ul>
*
* <li><p> To <i>encode</i> non-US-ASCII characters when a URI is required to
* conform strictly to RFC 2396 by not containing any <i>other</i>
* characters. </p></li>
*
* <li><p> To <i>quote</i> characters that are otherwise illegal in a
* component. The user-info, path, query, and fragment components differ
* slightly in terms of which characters are considered legal and illegal.
* </p></li>
*
* </ul>
*
* These purposes are served in this class by three related operations:
*
* <ul>
*
* <li><p><a name="encode"></a> A character is <i>encoded</i> by replacing it
* with the sequence of escaped octets that represent that character in the
* UTF-8 character set. The Euro currency symbol ({@code '\u005Cu20AC'}),
* for example, is encoded as {@code "%E2%82%AC"}. <i>(<b>Deviation from
* RFC 2396</b>, which does not specify any particular character
* set.)</i> </p></li>
*
* <li><p><a name="quote"></a> An illegal character is <i>quoted</i> simply by
* encoding it. The space character, for example, is quoted by replacing it
* with {@code "%20"}. UTF-8 contains US-ASCII, hence for US-ASCII
* characters this transformation has exactly the effect required by
* RFC 2396. </p></li>
*
* <li><p><a name="decode"></a>
* A sequence of escaped octets is <i>decoded</i> by
* replacing it with the sequence of characters that it represents in the
* UTF-8 character set. UTF-8 contains US-ASCII, hence decoding has the
* effect of de-quoting any quoted US-ASCII characters as well as that of
* decoding any encoded non-US-ASCII characters. If a <a
* href="../nio/charset/CharsetDecoder.html#ce">decoding error</a> occurs
* when decoding the escaped octets then the erroneous octets are replaced by
* {@code '\u005CuFFFD'}, the Unicode replacement character. </p></li>
*
* </ul>
*
* These operations are exposed in the constructors and methods of this class
* as follows:
*
* <ul>
*
* <li><p> The {@linkplain #URI(java.lang.String) single-argument
* constructor} requires any illegal characters in its argument to be
* quoted and preserves any escaped octets and <i>other</i> characters that
* are present. </p></li>
*
* <li><p> The {@linkplain
* #URI(java.lang.String,java.lang.String,java.lang.String,int,java.lang.String,java.lang.String,java.lang.String)
* multi-argument constructors} quote illegal characters as
* required by the components in which they appear. The percent character
* ({@code '%'}) is always quoted by these constructors. Any <i>other</i>
* characters are preserved. </p></li>
*
* <li><p> The {@link #getRawUserInfo() getRawUserInfo}, {@link #getRawPath()
* getRawPath}, {@link #getRawQuery() getRawQuery}, {@link #getRawFragment()
* getRawFragment}, {@link #getRawAuthority() getRawAuthority}, and {@link
* #getRawSchemeSpecificPart() getRawSchemeSpecificPart} methods return the
* values of their corresponding components in raw form, without interpreting
* any escaped octets. The strings returned by these methods may contain
* both escaped octets and <i>other</i> characters, and will not contain any
* illegal characters. </p></li>
*
* <li><p> The {@link #getUserInfo() getUserInfo}, {@link #getPath()
* getPath}, {@link #getQuery() getQuery}, {@link #getFragment()
* getFragment}, {@link #getAuthority() getAuthority}, and {@link
* #getSchemeSpecificPart() getSchemeSpecificPart} methods decode any escaped
* octets in their corresponding components. The strings returned by these
* methods may contain both <i>other</i> characters and illegal characters,
* and will not contain any escaped octets. </p></li>
*
* <li><p> The {@link #toString() toString} method returns a URI string with
* all necessary quotation but which may contain <i>other</i> characters.
* </p></li>
*
* <li><p> The {@link #toASCIIString() toASCIIString} method returns a fully
* quoted and encoded URI string that does not contain any <i>other</i>
* characters. </p></li>
*
* </ul>
*
*
* <h4> Identities </h4>
*
* For any URI <i>u</i>, it is always the case that
*
* <blockquote>
* {@code new URI(}<i>u</i>{@code .toString()).equals(}<i>u</i>{@code )} .
* </blockquote>
*
* For any URI <i>u</i> that does not contain redundant syntax such as two
* slashes before an empty authority (as in {@code file:///tmp/} ) or a
* colon following a host name but no port (as in
* {@code http://java.sun.com:} ), and that does not encode characters
* except those that must be quoted, the following identities also hold:
* <pre>
* new URI(<i>u</i>.getScheme(),
* <i>u</i>.getSchemeSpecificPart(),
* <i>u</i>.getFragment())
* .equals(<i>u</i>)</pre>
* in all cases,
* <pre>
* new URI(<i>u</i>.getScheme(),
* <i>u</i>.getUserInfo(), <i>u</i>.getAuthority(),
* <i>u</i>.getPath(), <i>u</i>.getQuery(),
* <i>u</i>.getFragment())
* .equals(<i>u</i>)</pre>
* if <i>u</i> is hierarchical, and
* <pre>
* new URI(<i>u</i>.getScheme(),
* <i>u</i>.getUserInfo(), <i>u</i>.getHost(), <i>u</i>.getPort(),
* <i>u</i>.getPath(), <i>u</i>.getQuery(),
* <i>u</i>.getFragment())
* .equals(<i>u</i>)</pre>
* if <i>u</i> is hierarchical and has either no authority or a server-based
* authority.
*
*
* <h4> URIs, URLs, and URNs </h4>
*
* A URI is a uniform resource <i>identifier</i> while a URL is a uniform
* resource <i>locator</i>. Hence every URL is a URI, abstractly speaking, but
* not every URI is a URL. This is because there is another subcategory of
* URIs, uniform resource <i>names</i> (URNs), which name resources but do not
* specify how to locate them. The {@code mailto}, {@code news}, and
* {@code isbn} URIs shown above are examples of URNs.
*
* <p> The conceptual distinction between URIs and URLs is reflected in the
* differences between this class and the {@link URL} class.
*
* <p> An instance of this class represents a URI reference in the syntactic
* sense defined by RFC 2396. A URI may be either absolute or relative.
* A URI string is parsed according to the generic syntax without regard to the
* scheme, if any, that it specifies. No lookup of the host, if any, is
* performed, and no scheme-dependent stream handler is constructed. Equality,
* hashing, and comparison are defined strictly in terms of the character
* content of the instance. In other words, a URI instance is little more than
* a structured string that supports the syntactic, scheme-independent
* operations of comparison, normalization, resolution, and relativization.
*
* <p> An instance of the {@link URL} class, by contrast, represents the
* syntactic components of a URL together with some of the information required
* to access the resource that it describes. A URL must be absolute, that is,
* it must always specify a scheme. A URL string is parsed according to its
* scheme. A stream handler is always established for a URL, and in fact it is
* impossible to create a URL instance for a scheme for which no handler is
* available. Equality and hashing depend upon both the scheme and the
* Internet address of the host, if any; comparison is not defined. In other
* words, a URL is a structured string that supports the syntactic operation of
* resolution as well as the network I/O operations of looking up the host and
* opening a connection to the specified resource.
*
*
* @author Mark Reinhold
* @since 1.4
*
* @see <a href="http://www.ietf.org/rfc/rfc2279.txt"><i>RFC 2279: UTF-8, a
* transformation format of ISO 10646</i></a>, <br><a
* href="http://www.ietf.org/rfc/rfc2373.txt"><i>RFC 2373: IPv6 Addressing
* Architecture</i></a>, <br><a
* href="http://www.ietf.org/rfc/rfc2396.txt"><i>RFC 2396: Uniform
* Resource Identifiers (URI): Generic Syntax</i></a>, <br><a
* href="http://www.ietf.org/rfc/rfc2732.txt"><i>RFC 2732: Format for
* Literal IPv6 Addresses in URLs</i></a>, <br><a
* href="URISyntaxException.html">URISyntaxException</a>
*/
public final class URI
implements Comparable<URI>, Serializable
{
// Note: Comments containing the word "ASSERT" indicate places where a
// throw of an InternalError should be replaced by an appropriate assertion
// statement once asserts are enabled in the build.
static final long serialVersionUID = -6052424284110960213L;
// -- Properties and components of this instance --
// Components of all URIs: [<scheme>:]<scheme-specific-part>[#<fragment>]
private transient String scheme; // null ==> relative URI
private transient String fragment;
// Hierarchical URI components: [//<authority>]<path>[?<query>]
private transient String authority; // Registry or server
// Server-based authority: [<userInfo>@]<host>[:<port>]
private transient String userInfo;
private transient String host; // null ==> registry-based
private transient int port = -1; // -1 ==> undefined
// Remaining components of hierarchical URIs
private transient String path; // null ==> opaque
private transient String query;
// The remaining fields may be computed on demand
private volatile transient String schemeSpecificPart;
private volatile transient int hash; // Zero ==> undefined
private volatile transient String decodedUserInfo = null;
private volatile transient String decodedAuthority = null;
private volatile transient String decodedPath = null;
private volatile transient String decodedQuery = null;
private volatile transient String decodedFragment = null;
private volatile transient String decodedSchemeSpecificPart = null;
/**
* The string form of this URI.
*
* @serial
*/
private volatile String string; // The only serializable field
// -- Constructors and factories --
private URI() { } // Used internally
/**
* Constructs a URI by parsing the given string.
*
* <p> This constructor parses the given string exactly as specified by the
* grammar in <a
* href="http://www.ietf.org/rfc/rfc2396.txt">RFC 2396</a>,
* Appendix A, <b><i>except for the following deviations:</i></b> </p>
*
* <ul>
*
* <li><p> An empty authority component is permitted as long as it is
* followed by a non-empty path, a query component, or a fragment
* component. This allows the parsing of URIs such as
* {@code "file:///foo/bar"}, which seems to be the intent of
* RFC 2396 although the grammar does not permit it. If the
* authority component is empty then the user-information, host, and port
* components are undefined. </p></li>
*
* <li><p> Empty relative paths are permitted; this seems to be the
* intent of RFC 2396 although the grammar does not permit it. The
* primary consequence of this deviation is that a standalone fragment
* such as {@code "#foo"} parses as a relative URI with an empty path
* and the given fragment, and can be usefully <a
* href="#resolve-frag">resolved</a> against a base URI.
*
* <li><p> IPv4 addresses in host components are parsed rigorously, as
* specified by <a
* href="http://www.ietf.org/rfc/rfc2732.txt">RFC 2732</a>: Each
* element of a dotted-quad address must contain no more than three
* decimal digits. Each element is further constrained to have a value
* no greater than 255. </p></li>
*
* <li> <p> Hostnames in host components that comprise only a single
* domain label are permitted to start with an <i>alphanum</i>
* character. This seems to be the intent of <a
* href="http://www.ietf.org/rfc/rfc2396.txt">RFC 2396</a>
* section 3.2.2 although the grammar does not permit it. The
* consequence of this deviation is that the authority component of a
* hierarchical URI such as {@code s://123}, will parse as a server-based
* authority. </p></li>
*
* <li><p> IPv6 addresses are permitted for the host component. An IPv6
* address must be enclosed in square brackets ({@code '['} and
* {@code ']'}) as specified by <a
* href="http://www.ietf.org/rfc/rfc2732.txt">RFC 2732</a>. The
* IPv6 address itself must parse according to <a
* href="http://www.ietf.org/rfc/rfc2373.txt">RFC 2373</a>. IPv6
* addresses are further constrained to describe no more than sixteen
* bytes of address information, a constraint implicit in RFC 2373
* but not expressible in the grammar. </p></li>
*
* <li><p> Characters in the <i>other</i> category are permitted wherever
* RFC 2396 permits <i>escaped</i> octets, that is, in the
* user-information, path, query, and fragment components, as well as in
* the authority component if the authority is registry-based. This
* allows URIs to contain Unicode characters beyond those in the US-ASCII
* character set. </p></li>
*
* </ul>
*
* @param str The string to be parsed into a URI
*
* @throws NullPointerException
* If {@code str} is {@code null}
*
* @throws URISyntaxException
* If the given string violates RFC 2396, as augmented
* by the above deviations
*/
public URI(String str) throws URISyntaxException {
new Parser(str).parse(false);
}
/**
* Constructs a hierarchical URI from the given components.
*
* <p> If a scheme is given then the path, if also given, must either be
* empty or begin with a slash character ({@code '/'}). Otherwise a
* component of the new URI may be left undefined by passing {@code null}
* for the corresponding parameter or, in the case of the {@code port}
* parameter, by passing {@code -1}.
*
* <p> This constructor first builds a URI string from the given components
* according to the rules specified in <a
* href="http://www.ietf.org/rfc/rfc2396.txt">RFC 2396</a>,
* section 5.2, step 7: </p>
*
* <ol>
*
* <li><p> Initially, the result string is empty. </p></li>
*
* <li><p> If a scheme is given then it is appended to the result,
* followed by a colon character ({@code ':'}). </p></li>
*
* <li><p> If user information, a host, or a port are given then the
* string {@code "//"} is appended. </p></li>
*
* <li><p> If user information is given then it is appended, followed by
* a commercial-at character ({@code '@'}). Any character not in the
* <i>unreserved</i>, <i>punct</i>, <i>escaped</i>, or <i>other</i>
* categories is <a href="#quote">quoted</a>. </p></li>
*
* <li><p> If a host is given then it is appended. If the host is a
* literal IPv6 address but is not enclosed in square brackets
* ({@code '['} and {@code ']'}) then the square brackets are added.
* </p></li>
*
* <li><p> If a port number is given then a colon character
* ({@code ':'}) is appended, followed by the port number in decimal.
* </p></li>
*
* <li><p> If a path is given then it is appended. Any character not in
* the <i>unreserved</i>, <i>punct</i>, <i>escaped</i>, or <i>other</i>
* categories, and not equal to the slash character ({@code '/'}) or the
* commercial-at character ({@code '@'}), is quoted. </p></li>
*
* <li><p> If a query is given then a question-mark character
* ({@code '?'}) is appended, followed by the query. Any character that
* is not a <a href="#legal-chars">legal URI character</a> is quoted.
* </p></li>
*
* <li><p> Finally, if a fragment is given then a hash character
* ({@code '#'}) is appended, followed by the fragment. Any character
* that is not a legal URI character is quoted. </p></li>
*
* </ol>
*
* <p> The resulting URI string is then parsed as if by invoking the {@link
* #URI(String)} constructor and then invoking the {@link
* #parseServerAuthority()} method upon the result; this may cause a {@link
* URISyntaxException} to be thrown. </p>
*
* @param scheme Scheme name
* @param userInfo User name and authorization information
* @param host Host name
* @param port Port number
* @param path Path
* @param query Query
* @param fragment Fragment
*
* @throws URISyntaxException
* If both a scheme and a path are given but the path is relative,
* if the URI string constructed from the given components violates
* RFC 2396, or if the authority component of the string is
* present but cannot be parsed as a server-based authority
*/
public URI(String scheme,
String userInfo, String host, int port,
String path, String query, String fragment)
throws URISyntaxException
{
String s = toString(scheme, null,
null, userInfo, host, port,
path, query, fragment);
checkPath(s, scheme, path);
new Parser(s).parse(true);
}
/**
* Constructs a hierarchical URI from the given components.
*
* <p> If a scheme is given then the path, if also given, must either be
* empty or begin with a slash character ({@code '/'}). Otherwise a
* component of the new URI may be left undefined by passing {@code null}
* for the corresponding parameter.
*
* <p> This constructor first builds a URI string from the given components
* according to the rules specified in <a
* href="http://www.ietf.org/rfc/rfc2396.txt">RFC 2396</a>,
* section 5.2, step 7: </p>
*
* <ol>
*
* <li><p> Initially, the result string is empty. </p></li>
*
* <li><p> If a scheme is given then it is appended to the result,
* followed by a colon character ({@code ':'}). </p></li>
*
* <li><p> If an authority is given then the string {@code "//"} is
* appended, followed by the authority. If the authority contains a
* literal IPv6 address then the address must be enclosed in square
* brackets ({@code '['} and {@code ']'}). Any character not in the
* <i>unreserved</i>, <i>punct</i>, <i>escaped</i>, or <i>other</i>
* categories, and not equal to the commercial-at character
* ({@code '@'}), is <a href="#quote">quoted</a>. </p></li>
*
* <li><p> If a path is given then it is appended. Any character not in
* the <i>unreserved</i>, <i>punct</i>, <i>escaped</i>, or <i>other</i>
* categories, and not equal to the slash character ({@code '/'}) or the
* commercial-at character ({@code '@'}), is quoted. </p></li>
*
* <li><p> If a query is given then a question-mark character
* ({@code '?'}) is appended, followed by the query. Any character that
* is not a <a href="#legal-chars">legal URI character</a> is quoted.
* </p></li>
*
* <li><p> Finally, if a fragment is given then a hash character
* ({@code '#'}) is appended, followed by the fragment. Any character
* that is not a legal URI character is quoted. </p></li>
*
* </ol>
*
* <p> The resulting URI string is then parsed as if by invoking the {@link
* #URI(String)} constructor and then invoking the {@link
* #parseServerAuthority()} method upon the result; this may cause a {@link
* URISyntaxException} to be thrown. </p>
*
* @param scheme Scheme name
* @param authority Authority
* @param path Path
* @param query Query
* @param fragment Fragment
*
* @throws URISyntaxException
* If both a scheme and a path are given but the path is relative,
* if the URI string constructed from the given components violates
* RFC 2396, or if the authority component of the string is
* present but cannot be parsed as a server-based authority
*/
public URI(String scheme,
String authority,
String path, String query, String fragment)
throws URISyntaxException
{
String s = toString(scheme, null,
authority, null, null, -1,
path, query, fragment);
checkPath(s, scheme, path);
new Parser(s).parse(false);
}
/**
* Constructs a hierarchical URI from the given components.
*
* <p> A component may be left undefined by passing {@code null}.
*
* <p> This convenience constructor works as if by invoking the
* seven-argument constructor as follows:
*
* <blockquote>
* {@code new} {@link #URI(String, String, String, int, String, String, String)
* URI}{@code (scheme, null, host, -1, path, null, fragment);}
* </blockquote>
*
* @param scheme Scheme name
* @param host Host name
* @param path Path
* @param fragment Fragment
*
* @throws URISyntaxException
* If the URI string constructed from the given components
* violates RFC 2396
*/
public URI(String scheme, String host, String path, String fragment)
throws URISyntaxException
{
this(scheme, null, host, -1, path, null, fragment);
}
/**
* Constructs a URI from the given components.
*
* <p> A component may be left undefined by passing {@code null}.
*
* <p> This constructor first builds a URI in string form using the given
* components as follows: </p>
*
* <ol>
*
* <li><p> Initially, the result string is empty. </p></li>
*
* <li><p> If a scheme is given then it is appended to the result,
* followed by a colon character ({@code ':'}). </p></li>
*
* <li><p> If a scheme-specific part is given then it is appended. Any
* character that is not a <a href="#legal-chars">legal URI character</a>
* is <a href="#quote">quoted</a>. </p></li>
*
* <li><p> Finally, if a fragment is given then a hash character
* ({@code '#'}) is appended to the string, followed by the fragment.
* Any character that is not a legal URI character is quoted. </p></li>
*
* </ol>
*
* <p> The resulting URI string is then parsed in order to create the new
* URI instance as if by invoking the {@link #URI(String)} constructor;
* this may cause a {@link URISyntaxException} to be thrown. </p>
*
* @param scheme Scheme name
* @param ssp Scheme-specific part
* @param fragment Fragment
*
* @throws URISyntaxException
* If the URI string constructed from the given components
* violates RFC 2396
*/
public URI(String scheme, String ssp, String fragment)
throws URISyntaxException
{
new Parser(toString(scheme, ssp,
null, null, null, -1,
null, null, fragment))
.parse(false);
}
/**
* Creates a URI by parsing the given string.
*
* <p> This convenience factory method works as if by invoking the {@link
* #URI(String)} constructor; any {@link URISyntaxException} thrown by the
* constructor is caught and wrapped in a new {@link
* IllegalArgumentException} object, which is then thrown.
*
* <p> This method is provided for use in situations where it is known that
* the given string is a legal URI, for example for URI constants declared
* within in a program, and so it would be considered a programming error
* for the string not to parse as such. The constructors, which throw
* {@link URISyntaxException} directly, should be used situations where a
* URI is being constructed from user input or from some other source that
* may be prone to errors. </p>
*
* @param str The string to be parsed into a URI
* @return The new URI
*
* @throws NullPointerException
* If {@code str} is {@code null}
*
* @throws IllegalArgumentException
* If the given string violates RFC 2396
*/
public static URI create(String str) {
try {
return new URI(str);
} catch (URISyntaxException x) {
throw new IllegalArgumentException(x.getMessage(), x);
}
}
// -- Operations --
/**
* Attempts to parse this URI's authority component, if defined, into
* user-information, host, and port components.
*
* <p> If this URI's authority component has already been recognized as
* being server-based then it will already have been parsed into
* user-information, host, and port components. In this case, or if this
* URI has no authority component, this method simply returns this URI.
*
* <p> Otherwise this method attempts once more to parse the authority
* component into user-information, host, and port components, and throws
* an exception describing why the authority component could not be parsed
* in that way.
*
* <p> This method is provided because the generic URI syntax specified in
* <a href="http://www.ietf.org/rfc/rfc2396.txt">RFC 2396</a>
* cannot always distinguish a malformed server-based authority from a
* legitimate registry-based authority. It must therefore treat some
* instances of the former as instances of the latter. The authority
* component in the URI string {@code "//foo:bar"}, for example, is not a
* legal server-based authority but it is legal as a registry-based
* authority.
*
* <p> In many common situations, for example when working URIs that are
* known to be either URNs or URLs, the hierarchical URIs being used will
* always be server-based. They therefore must either be parsed as such or
* treated as an error. In these cases a statement such as
*
* <blockquote>
* {@code URI }<i>u</i>{@code = new URI(str).parseServerAuthority();}
* </blockquote>
*
* <p> can be used to ensure that <i>u</i> always refers to a URI that, if
* it has an authority component, has a server-based authority with proper
* user-information, host, and port components. Invoking this method also
* ensures that if the authority could not be parsed in that way then an
* appropriate diagnostic message can be issued based upon the exception
* that is thrown. </p>
*
* @return A URI whose authority field has been parsed
* as a server-based authority
*
* @throws URISyntaxException
* If the authority component of this URI is defined
* but cannot be parsed as a server-based authority
* according to RFC 2396
*/
public URI parseServerAuthority()
throws URISyntaxException
{
// We could be clever and cache the error message and index from the
// exception thrown during the original parse, but that would require
// either more fields or a more-obscure representation.
if ((host != null) || (authority == null))
return this;
defineString();
new Parser(string).parse(true);
return this;
}
/**
* Normalizes this URI's path.
*
* <p> If this URI is opaque, or if its path is already in normal form,
* then this URI is returned. Otherwise a new URI is constructed that is
* identical to this URI except that its path is computed by normalizing
* this URI's path in a manner consistent with <a
* href="http://www.ietf.org/rfc/rfc2396.txt">RFC 2396</a>,
* section 5.2, step 6, sub-steps c through f; that is:
* </p>
*
* <ol>
*
* <li><p> All {@code "."} segments are removed. </p></li>
*
* <li><p> If a {@code ".."} segment is preceded by a non-{@code ".."}
* segment then both of these segments are removed. This step is
* repeated until it is no longer applicable. </p></li>
*
* <li><p> If the path is relative, and if its first segment contains a
* colon character ({@code ':'}), then a {@code "."} segment is
* prepended. This prevents a relative URI with a path such as
* {@code "a:b/c/d"} from later being re-parsed as an opaque URI with a
* scheme of {@code "a"} and a scheme-specific part of {@code "b/c/d"}.
* <b><i>(Deviation from RFC 2396)</i></b> </p></li>
*
* </ol>
*
* <p> A normalized path will begin with one or more {@code ".."} segments
* if there were insufficient non-{@code ".."} segments preceding them to
* allow their removal. A normalized path will begin with a {@code "."}
* segment if one was inserted by step 3 above. Otherwise, a normalized
* path will not contain any {@code "."} or {@code ".."} segments. </p>
*
* @return A URI equivalent to this URI,
* but whose path is in normal form
*/
public URI normalize() {
return normalize(this);
}
/**
* Resolves the given URI against this URI.
*
* <p> If the given URI is already absolute, or if this URI is opaque, then
* the given URI is returned.
*
* <p><a name="resolve-frag"></a> If the given URI's fragment component is
* defined, its path component is empty, and its scheme, authority, and
* query components are undefined, then a URI with the given fragment but
* with all other components equal to those of this URI is returned. This
* allows a URI representing a standalone fragment reference, such as
* {@code "#foo"}, to be usefully resolved against a base URI.
*
* <p> Otherwise this method constructs a new hierarchical URI in a manner
* consistent with <a
* href="http://www.ietf.org/rfc/rfc2396.txt">RFC 2396</a>,
* section 5.2; that is: </p>
*
* <ol>
*
* <li><p> A new URI is constructed with this URI's scheme and the given
* URI's query and fragment components. </p></li>
*
* <li><p> If the given URI has an authority component then the new URI's
* authority and path are taken from the given URI. </p></li>
*
* <li><p> Otherwise the new URI's authority component is copied from
* this URI, and its path is computed as follows: </p>
*
* <ol>
*
* <li><p> If the given URI's path is absolute then the new URI's path
* is taken from the given URI. </p></li>
*
* <li><p> Otherwise the given URI's path is relative, and so the new
* URI's path is computed by resolving the path of the given URI
* against the path of this URI. This is done by concatenating all but
* the last segment of this URI's path, if any, with the given URI's
* path and then normalizing the result as if by invoking the {@link
* #normalize() normalize} method. </p></li>
*