Quelle URI.java Sprache: JAVA

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package java.net;

import java.io.File;
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.nio.file.Path;
import java.text.Normalizer;
import jdk.internal.access.JavaNetUriAccess;
import jdk.internal.access.SharedSecrets;
import sun.nio.cs.UTF_8;

/**
* Represents a Uniform Resource Identifier (URI) reference.
*
* 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">RFC 2396: Uniform
* Resource Identifiers (URI): Generic Syntax</a>, amended by <a
* href="http://www.ietf.org/rfc/rfc2732.txt">RFC 2732: Format for
* Literal IPv6 Addresses in URLs</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.
*
*
* <h2> URI syntax and components </h2>
*
* At the highest level a URI reference (hereinafter simply "URI") in string
* form has the syntax
*
* <blockquote>
* [scheme{@code :}]scheme-specific-part[{@code #}fragment]
* </blockquote>
*
* where square brackets [...] delineate optional components and the characters
* {@code :} and {@code #} stand for themselves.
*
* An absolute URI specifies a scheme; a URI that is not absolute is
* said to be relative. URIs are also classified according to whether
* they are opaque or hierarchical.
*
* An opaque 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><ul style="list-style-type:none">
* <li>{@code mailto:java-net@www.example.com}</li>
* <li>{@code news:comp.lang.java}</li>
* <li>{@code urn:isbn:096139210x}</li>
* </ul></blockquote>
*
* A hierarchical 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://example.com/languages/java/} 
* {@code sample/a/index.html#28} 
* {@code ../../demo/b/index.html} 
* {@code file:///~/calendar}
* </blockquote>
*
* A hierarchical URI is subject to further parsing according to the syntax
*
* <blockquote>
* [scheme{@code :}][{@code //}authority][path][{@code ?}query][{@code #}fragment]
* </blockquote>
*
* where the characters {@code :}, {@code /},
* {@code ?}, and {@code #} stand for themselves. The
* scheme-specific part of a hierarchical URI consists of the characters
* between the scheme and fragment components.
*
* The authority component of a hierarchical URI is, if specified, either
* server-based or registry-based. A server-based authority
* parses according to the familiar syntax
*
* <blockquote>
* [user-info{@code @}]host[{@code :}port]
* </blockquote>
*
* where the characters {@code @} and {@code :} 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.
*
* 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.
*
* All told, then, a URI instance has the following nine components:
*
* <table class="striped" style="margin-left:2em">
* <caption style="display:none">Describes the components of a URI:scheme,scheme-specific-part,authority,user-info,host,port,path,query,fragment</caption>
* <thead>
* <tr><th scope="col">Component</th><th scope="col">Type</th></tr>
* </thead>
* <tbody style="text-align:left">
* <tr><th scope="row">scheme</th><td>{@code String}</td></tr>
* <tr><th scope="row">scheme-specific-part</th><td>{@code String}</td></tr>
* <tr><th scope="row">authority</th><td>{@code String}</td></tr>
* <tr><th scope="row">user-info</th><td>{@code String}</td></tr>
* <tr><th scope="row">host</th><td>{@code String}</td></tr>
* <tr><th scope="row">port</th><td>{@code int}</td></tr>
* <tr><th scope="row">path</th><td>{@code String}</td></tr>
* <tr><th scope="row">query</th><td>{@code String}</td></tr>
* <tr><th scope="row">fragment</th><td>{@code String}</td></tr>
* </tbody>
* </table>
*
* In a given instance any particular component is either undefined or
* defined 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.
*
* 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.
*
*
* <h3> Operations on URI instances </h3>
*
* The key operations supported by this class are those of
* normalization, resolution, and relativization.
*
* Normalization 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.
*
* Resolution is the process of resolving one URI against another,
* base 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 sample/a/index.html#28}
*
* (1)
* </blockquote>
*
* against the base URI {@code http://example.com/languages/java/} is the result
* URI
*
* <blockquote>
* {@code http://example.com/languages/java/sample/a/index.html#28}
* </blockquote>
*
* Resolving the relative URI
*
* <blockquote>
* {@code ../../demo/b/index.html} (2)
* </blockquote>
*
* against this result yields, in turn,
*
* <blockquote>
* {@code http://example.com/languages/java/demo/b/index.html}
* </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/b/index.html}
* </blockquote>
*
* Relativization, finally, can be regarded as the inverse of resolution.
* Let u be any normalized absolute URI ending with a slash character ({@code '/'})
* and v be any normalized relative URI not beginning with a period character ({@code '.'})
* or slash character ({@code '/'}). Then, the following statement is true:
*
* <blockquote>
* u{@code .relativize(}u{@code .resolve(}v{@code )).equals(}v{@code )}
* </blockquote>
*
* Let u be any normalized absolute URI ending with a slash character ({@code '/'})
* and v be any normalized absolute URI. Then, the following statement is true:
*
* <blockquote>
* u{@code .resolve(}u{@code .relativize(}v{@code )).equals(}v{@code )}
* </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 http://example.com/languages/java/sample/a/index.html#28}
* </blockquote>
*
* against the base URI
*
* <blockquote>
* {@code http://example.com/languages/java/}
* </blockquote>
*
* yields the relative URI {@code sample/a/index.html#28}.
*
*
* <h3> Character categories </h3>
*
* 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:
*
* <table class="striped" style="margin-left:2em">
* <caption style="display:none">Describes categories alpha,digit,alphanum,unreserved,punct,reserved,escaped,and other</caption>
* <thead>
* <tr><th scope="col">Category</th><th scope="col">Description</th></tr>
* </thead>
* <tbody style="text-align:left">
* <tr><th scope="row" style="vertical-align:top">alpha</th>
* <td>The US-ASCII alphabetic characters,
* {@code 'A'} through {@code 'Z'}
* and {@code 'a'} through {@code 'z'}</td></tr>
* <tr><th scope="row" style="vertical-align:top">digit</th>
* <td>The US-ASCII decimal digit characters,
* {@code '0'} through {@code '9'}</td></tr>
* <tr><th scope="row" style="vertical-align:top">alphanum</th>
* <td>All alpha and digit characters</td></tr>
* <tr><th scope="row" style="vertical-align:top">unreserved</th>
* <td>All alphanum characters together with those in the string
* {@code "_-!.~'()*"}</td></tr>
* <tr><th scope="row" style="vertical-align:top">punct</th>
* <td>The characters in the string {@code ",;:$&+="}</td></tr>
* <tr><th scope="row" style="vertical-align:top">reserved</th>
* <td>All punct characters together with those in the string
* {@code "?/[]@"}</td></tr>
* <tr><th scope="row" style="vertical-align:top">escaped</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 scope="row" style="vertical-align:top">other</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) (Deviation from RFC 2396, which is
* limited to US-ASCII)</td></tr>
* </tbody>
* </table>
*
* <a id="legal-chars"></a> The set of all legal URI characters consists of
* the unreserved, reserved, escaped, and other
* characters.
*
*
* <h3> Escaped octets, quotation, encoding, and decoding </h3>
*
* RFC 2396 allows escaped octets to appear in the user-info, path, query, and
* fragment components. Escaping serves two purposes in URIs:
*
* <ul>
*
* <li> To encode non-US-ASCII characters when a URI is required to
* conform strictly to RFC 2396 by not containing any other
* characters. </li>
*
* <li> To quote 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.
* </li>
*
* </ul>
*
* These purposes are served in this class by three related operations:
*
* <ul>
*
* <li><a id="encode"></a> A character is encoded 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"}. (Deviation from
* RFC 2396, which does not specify any particular character
* set.) </li>
*
* <li><a id="quote"></a> An illegal character is quoted 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. </li>
*
* <li><a id="decode"></a>
* A sequence of escaped octets is decoded 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. </li>
*
* </ul>
*
* These operations are exposed in the constructors and methods of this class
* as follows:
*
* <ul>
*
* <li> 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 other characters that
* are present. </li>
*
* <li> 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 other
* characters are preserved. </li>
*
* <li> 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 other characters, and will not contain any
* illegal characters. </li>
*
* <li> 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 other characters and illegal characters,
* and will not contain any escaped octets. </li>
*
* <li> The {@link #toString() toString} method returns a URI string with
* all necessary quotation but which may contain other characters.
* </li>
*
* <li> The {@link #toASCIIString() toASCIIString} method returns a fully
* quoted and encoded URI string that does not contain any other
* characters. </li>
*
* </ul>
*
*
* <h3> Identities </h3>
*
* For any URI u, it is always the case that
*
* <blockquote>
* {@code new URI(}u{@code .toString()).equals(}u{@code )} .
* </blockquote>
*
* For any URI u 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://www.example.com:} ), and that does not encode characters
* except those that must be quoted, the following identities also hold:
* <pre>
* new URI(u.getScheme(),
* u.getSchemeSpecificPart(),
* u.getFragment())
* .equals(u)</pre>
* in all cases,
* <pre>
* new URI(u.getScheme(),
* u.getAuthority(),
* u.getPath(), u.getQuery(),
* u.getFragment())
* .equals(u)</pre>
* if u is hierarchical, and
* <pre>
* new URI(u.getScheme(),
* u.getUserInfo(), u.getHost(), u.getPort(),
* u.getPath(), u.getQuery(),
* u.getFragment())
* .equals(u)</pre>
* if u is hierarchical and has either no authority or a server-based
* authority.
*
*
* <h3> URIs, URLs, and URNs </h3>
*
* A URI is a uniform resource identifier while a URL is a uniform
* resource locator. 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 names (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.
*
* The conceptual distinction between URIs and URLs is reflected in the
* differences between this class and the {@link URL} class.
*
* 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.
*
* 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.
*
* @apiNote
*
* Applications working with file paths and file URIs should take great
* care to use the appropriate methods to convert between the two.
* The {@link Path#of(URI)} factory method and the {@link File#File(URI)}
* constructor can be used to create {@link Path} or {@link File}
* objects from a file URI. {@link Path#toUri()} and {@link File#toURI()}
* can be used to create a {@link URI} from a file path.
* Applications should never try to {@linkplain
* #URI(String, String, String, int, String, String, String)
* construct}, {@linkplain #URI(String) parse}, or
* {@linkplain #resolve(String) resolve} a {@code URI}
* from the direct string representation of a {@code File} or {@code Path}
* instance.
* 
* Some components of a URL or URI, such as userinfo, may
* be abused to construct misleading URLs or URIs. Applications
* that deal with URLs or URIs should take into account
* the recommendations advised in <a
* href="https://tools.ietf.org/html/rfc3986#section-7">RFC3986,
* Section 7, Security Considerations</a>.
*
* @author Mark Reinhold
* @since 1.4
*
* @see <a href="http://www.ietf.org/rfc/rfc2279.txt">RFC 2279: UTF-8, a
* transformation format of ISO 10646</a>
* @see <a href="http://www.ietf.org/rfc/rfc2373.txt">RFC 2373: IPv6 Addressing
* Architecture</a>
* @see <a href="http://www.ietf.org/rfc/rfc2396.txt">RFC 2396: Uniform
* Resource Identifiers (URI): Generic Syntax</a>
* @see <a href="http://www.ietf.org/rfc/rfc2732.txt">RFC 2732: Format for
* Literal IPv6 Addresses in URLs</a>
* @see <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.
 @java.io.Serial
 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, which is safe even in
 // the face of multiple threads racing to initialize them
 private transient String schemeSpecificPart;
 private transient int hash; // Zero ==> undefined

 private transient String decodedUserInfo;
 private transient String decodedAuthority;
 private transient String decodedPath;
 private transient String decodedQuery;
 private transient String decodedFragment;
 private transient String decodedSchemeSpecificPart;

 /**
 * 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.
 *
 * 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, except for the following deviations: 
 *
 * <ul>
 *
 * <li> 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. </li>
 *
 * <li> 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> 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. </li>
 *
 * <li> Hostnames in host components that comprise only a single
 * domain label are permitted to start with an alphanum
 * 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. </li>
 *
 * <li> 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. </li>
 *
 * <li> Characters in the other category are permitted wherever
 * RFC 2396 permits escaped 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. </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.
 *
 * 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}.
 *
 * 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: 
 *
 * <ol>
 *
 * <li> Initially, the result string is empty. </li>
 *
 * <li> If a scheme is given then it is appended to the result,
 * followed by a colon character ({@code ':'}). </li>
 *
 * <li> If user information, a host, or a port are given then the
 * string {@code "//"} is appended. </li>
 *
 * <li> If user information is given then it is appended, followed by
 * a commercial-at character ({@code '@'}). Any character not in the
 * unreserved, punct, escaped, or other
 * categories is <a href="#quote">quoted</a>. </li>
 *
 * <li> 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.
 * </li>
 *
 * <li> If a port number is given then a colon character
 * ({@code ':'}) is appended, followed by the port number in decimal.
 * </li>
 *
 * <li> If a path is given then it is appended. Any character not in
 * the unreserved, punct, escaped, or other
 * categories, and not equal to the slash character ({@code '/'}) or the
 * commercial-at character ({@code '@'}), is quoted. </li>
 *
 * <li> 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.
 * </li>
 *
 * <li> 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. </li>
 *
 * </ol>
 *
 * 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. 
 *
 * @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.
 *
 * 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.
 *
 * 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: 
 *
 * <ol>
 *
 * <li> Initially, the result string is empty. </li>
 *
 * <li> If a scheme is given then it is appended to the result,
 * followed by a colon character ({@code ':'}). </li>
 *
 * <li> 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
 * unreserved, punct, escaped, or other
 * categories, and not equal to the commercial-at character
 * ({@code '@'}), is <a href="#quote">quoted</a>. </li>
 *
 * <li> If a path is given then it is appended. Any character not in
 * the unreserved, punct, escaped, or other
 * categories, and not equal to the slash character ({@code '/'}) or the
 * commercial-at character ({@code '@'}), is quoted. </li>
 *
 * <li> 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.
 * </li>
 *
 * <li> 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. </li>
 *
 * </ol>
 *
 * 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. 
 *
 * @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.
 *
 * A component may be left undefined by passing {@code null}.
 *
 * 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.
 *
 * A component may be left undefined by passing {@code null}.
 *
 * This constructor first builds a URI in string form using the given
 * components as follows: 
 *
 * <ol>
 *
 * <li> Initially, the result string is empty. </li>
 *
 * <li> If a scheme is given then it is appended to the result,
 * followed by a colon character ({@code ':'}). </li>
 *
 * <li> 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>. </li>
 *
 * <li> 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. </li>
 *
 * </ol>
 *
 * 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. 
 *
 * @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);
 }

 /**
 * Constructs a simple URI consisting of only a scheme and a pre-validated
 * path. Provides a fast-path for some internal cases.
 */
 URI(String scheme, String path) {
 assert validSchemeAndPath(scheme, path);
 this.scheme = scheme;
 this.path = path;
 }

 private static boolean validSchemeAndPath(String scheme, String path) {
 try {
 URI u = new URI(scheme + ':' + path);
 return scheme.equals(u.scheme) && path.equals(u.path);
 } catch (URISyntaxException e) {
 return false;
 }
 }

 /**
 * Creates a URI by parsing the given string.
 *
 * 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.
 *
 * 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 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 in situations where a
 * URI is being constructed from user input or from some other source that
 * may be prone to errors. 
 *
 * @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.
 *
 * 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.
 *
 * 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.
 *
 * 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.
 *
 * 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 }u{@code = new URI(str).parseServerAuthority();}
 * </blockquote>
 *
 * can be used to ensure that u 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. 
 *
 * @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;
 new Parser(toString()).parse(true);
 return this;
 }

 /**
 * Normalizes this URI's path.
 *
 * 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:
 * 
 *
 * <ol>
 *
 * <li> All {@code "."} segments are removed. </li>
 *
 * <li> 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. </li>
 *
 * <li> 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"}.
 * (Deviation from RFC 2396) </li>
 *
 * </ol>
 *
 * 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. 
 *
 * @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.
 *
 * If the given URI is already absolute, or if this URI is opaque, then
 * the given URI is returned.
 *
 * <a id="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.
 *
 * 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: 
 *
 * <ol>
 *
 * <li> A new URI is constructed with this URI's scheme and the given
 * URI's query and fragment components. </li>
 *
 * <li> If the given URI has an authority component then the new URI's
 * authority and path are taken from the given URI. </li>
 *
 * <li> Otherwise the new URI's authority component is copied from
 * this URI, and its path is computed as follows: 
 *
 * <ol>
 *
 * <li> If the given URI's path is absolute then the new URI's path
 * is taken from the given URI. </li>
 *
 * <li> 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. </li>
 *
 * </ol></li>
 *
 * </ol>
 *
 * The result of this method is absolute if, and only if, either this
 * URI is absolute or the given URI is absolute. 
 *
 * @param uri The URI to be resolved against this URI
 * @return The resulting URI
 *
 * @throws NullPointerException
 * If {@code uri} is {@code null}
 */
 public URI resolve(URI uri) {
 return resolve(this, uri);
 }

 /**
 * Constructs a new URI by parsing the given string and then resolving it
 * against this URI.
 *
 * This convenience method works as if invoking it were equivalent to
 * evaluating the expression {@link #resolve(java.net.URI)
 * resolve}{@code (URI.}{@link #create(String) create}{@code (str))}. 
 *
 * @param str The string to be parsed into a URI
 * @return The resulting URI
 *
 * @throws NullPointerException
 * If {@code str} is {@code null}
 *
 * @throws IllegalArgumentException
 * If the given string violates RFC 2396
 */
 public URI resolve(String str) {
 return resolve(URI.create(str));
 }

 /**
 * Relativizes the given URI against this URI.
 *
 * The relativization of the given URI against this URI is computed as
 * follows: 
 *
 * <ol>
 *
 * <li> If either this URI or the given URI are opaque, or if the
 * scheme and authority components of the two URIs are not identical, or
 * if the path of this URI is not a prefix of the path of the given URI,
 * then the given URI is returned. </li>
 *
 * <li> Otherwise a new relative hierarchical URI is constructed with
 * query and fragment components taken from the given URI and with a path
 * component computed by removing this URI's path from the beginning of
 * the given URI's path. </li>
 *
 * </ol>
 *
 * @param uri The URI to be relativized against this URI
 * @return The resulting URI
 *
 * @throws NullPointerException
 * If {@code uri} is {@code null}
 */
 public URI relativize(URI uri) {
 return relativize(this, uri);
 }

 /**
 * Constructs a URL from this URI.
 *
 * This convenience method works as if invoking it were equivalent to
 * evaluating the expression {@code new URL(this.toString())} after
 * first checking that this URI is absolute. 
 *
 * @return A URL constructed from this URI
 *
 * @throws IllegalArgumentException
 * If this URL is not absolute
 *
 * @throws MalformedURLException
 * If a protocol handler for the URL could not be found,
 * or if some other error occurred while constructing the URL
 */
 public URL toURL() throws MalformedURLException {
 return URL.of(this, null);
 }

 // -- Component access methods --

 /**
 * Returns the scheme component of this URI.
 *
 * The scheme component of a URI, if defined, only contains characters
 * in the alphanum category and in the string {@code "-.+"}. A
 * scheme always starts with an alpha character. 
 *
 * The scheme component of a URI cannot contain escaped octets, hence this
 * method does not perform any decoding.
 *
 * @return The scheme component of this URI,
 * or {@code null} if the scheme is undefined
 */
 public String getScheme() {
 return scheme;
 }

 /**
 * Tells whether or not this URI is absolute.
 *
 * A URI is absolute if, and only if, it has a scheme component. 
 *
 * @return {@code true} if, and only if, this URI is absolute
 */
 public boolean isAbsolute() {
 return scheme != null;
 }

 /**
 * Tells whether or not this URI is opaque.
 *
 * A URI is opaque if, and only if, it is absolute and its
 * scheme-specific part does not begin with a slash character ('/').
 * An opaque URI has a scheme, a scheme-specific part, and possibly
 * a fragment; all other components are undefined. 
 *
 * @return {@code true} if, and only if, this URI is opaque
 */
 public boolean isOpaque() {
 return path == null;
 }

 /**
 * Returns the raw scheme-specific part of this URI. The scheme-specific
 * part is never undefined, though it may be empty.
 *
 * The scheme-specific part of a URI only contains legal URI
 * characters. 
 *
 * @return The raw scheme-specific part of this URI
 * (never {@code null})
 */
 public String getRawSchemeSpecificPart() {
 String part = schemeSpecificPart;
 if (part != null) {
 return part;
 }

 String s = string;
 if (s != null) {
 // if string is defined, components will have been parsed
 int start = 0;
 int end = s.length();
 if (scheme != null) {
 start = scheme.length() + 1;
 }
 if (fragment != null) {
 end -= fragment.length() + 1;
 }
 if (path != null && path.length() == end - start) {
 part = path;
 } else {
 part = s.substring(start, end);
 }
 } else {
 StringBuilder sb = new StringBuilder();
 appendSchemeSpecificPart(sb, null, getAuthority(), getUserInfo(),
 host, port, getPath(), getQuery());
 part = sb.toString();
 }
 return schemeSpecificPart = part;
 }

 /**
 * Returns the decoded scheme-specific part of this URI.
 *
 * The string returned by this method is equal to that returned by the
 * {@link #getRawSchemeSpecificPart() getRawSchemeSpecificPart} method
 * except that all sequences of escaped octets are <a
 * href="#decode">decoded</a>. 
 *
 * @return The decoded scheme-specific part of this URI
 * (never {@code null})
 */
 public String getSchemeSpecificPart() {
 String part = decodedSchemeSpecificPart;
 if (part == null) {
 decodedSchemeSpecificPart = part = decode(getRawSchemeSpecificPart());
 }
 return part;
 }

 /**
 * Returns the raw authority component of this URI.
 *
 * The authority component of a URI, if defined, only contains the
 * commercial-at character ({@code '@'}) and characters in the
 * unreserved, punct, escaped, and other
 * categories. If the authority is server-based then it is further
 * constrained to have valid user-information, host, and port
 * components. 
 *
 * @return The raw authority component of this URI,
 * or {@code null} if the authority is undefined
 */
 public String getRawAuthority() {
 return authority;
 }

 /**
 * Returns the decoded authority component of this URI.
 *
 * The string returned by this method is equal to that returned by the
 * {@link #getRawAuthority() getRawAuthority} method except that all
 * sequences of escaped octets are <a href="#decode">decoded</a>. 
 *
 * @return The decoded authority component of this URI,
 * or {@code null} if the authority is undefined
 */
 public String getAuthority() {
 String auth = decodedAuthority;
 if ((auth == null) && (authority != null)) {
 decodedAuthority = auth = decode(authority);
 }
 return auth;
 }

 /**
 * Returns the raw user-information component of this URI.
 *
 * The user-information component of a URI, if defined, only contains
 * characters in the unreserved, punct, escaped, and
 * other categories. 
 *
 * @return The raw user-information component of this URI,
 * or {@code null} if the user information is undefined
 */
 public String getRawUserInfo() {
 return userInfo;
 }

 /**
 * Returns the decoded user-information component of this URI.
 *
 * The string returned by this method is equal to that returned by the
 * {@link #getRawUserInfo() getRawUserInfo} method except that all
 * sequences of escaped octets are <a href="#decode">decoded</a>. 
 *
 * @return The decoded user-information component of this URI,
 * or {@code null} if the user information is undefined
 */
 public String getUserInfo() {
 String user = decodedUserInfo;
 if ((user == null) && (userInfo != null)) {
 decodedUserInfo = user = decode(userInfo);
 }
 return user;
 }

 /**
 * Returns the host component of this URI.
 *
 * The host component of a URI, if defined, will have one of the
 * following forms: 
 *
 * <ul>
 *
 * <li> A domain name consisting of one or more labels
 * separated by period characters ({@code '.'}), optionally followed by
 * a period character. Each label consists of alphanum characters
 * as well as hyphen characters ({@code '-'}), though hyphens never
 * occur as the first or last characters in a label. The rightmost
 * label of a domain name consisting of two or more labels, begins
 * with an alpha character. </li>
 *
 * <li> A dotted-quad IPv4 address of the form
 * digit{@code +.}digit{@code +.}digit{@code +.}digit{@code +},
 * where no digit sequence is longer than three characters and no
 * sequence has a value larger than 255. </li>
 *
 * <li> An IPv6 address enclosed in square brackets ({@code '['} and
 * {@code ']'}) and consisting of hexadecimal digits, colon characters
 * ({@code ':'}), and possibly an embedded IPv4 address. The full
 * syntax of IPv6 addresses is specified in <a
 * href="http://www.ietf.org/rfc/rfc2373.txt">RFC 2373: IPv6
 * Addressing Architecture</a>. </li>
 *
 * </ul>
 *
 * The host component of a URI cannot contain escaped octets, hence this
 * method does not perform any decoding.
 *
 * @return The host component of this URI,
 * or {@code null} if the host is undefined
 */
 public String getHost() {
 return host;
 }

 /**
 * Returns the port number of this URI.
 *
 * The port component of a URI, if defined, is a non-negative
 * integer. 
 *
 * @return The port component of this URI,
 * or {@code -1} if the port is undefined
 */
 public int getPort() {
 return port;
 }

 /**
 * Returns the raw path component of this URI.
 *
 * The path component of a URI, if defined, only contains the slash
 * character ({@code '/'}), the commercial-at character ({@code '@'}),
 * and characters in the unreserved, punct, escaped,
 * and other categories. 
 *
 * @return The path component of this URI,
 * or {@code null} if the path is undefined
 */
 public String getRawPath() {
 return path;
 }

 /**
 * Returns the decoded path component of this URI.
 *
 * The string returned by this method is equal to that returned by the
 * {@link #getRawPath() getRawPath} method except that all sequences of
 * escaped octets are <a href="#decode">decoded</a>. 
 *
 * @return The decoded path component of this URI,
 * or {@code null} if the path is undefined
 */
 public String getPath() {
 String decoded = decodedPath;
 if ((decoded == null) && (path != null)) {
 decodedPath = decoded = decode(path);
 }
 return decoded;
 }

 /**
 * Returns the raw query component of this URI.
 *
 * The query component of a URI, if defined, only contains legal URI
 * characters. 
 *
 * @return The raw query component of this URI,
 * or {@code null} if the query is undefined
 */
 public String getRawQuery() {
 return query;
 }

 /**
 * Returns the decoded query component of this URI.
 *
 * The string returned by this method is equal to that returned by the
 * {@link #getRawQuery() getRawQuery} method except that all sequences of
 * escaped octets are <a href="#decode">decoded</a>. 
 *
 * @return The decoded query component of this URI,
 * or {@code null} if the query is undefined
 */
 public String getQuery() {
 String decoded = decodedQuery;
 if ((decoded == null) && (query != null)) {
 decodedQuery = decoded = decode(query, false);
 }
 return decoded;
 }

 /**
 * Returns the raw fragment component of this URI.
 *
 * The fragment component of a URI, if defined, only contains legal URI
 * characters. 
 *
 * @return The raw fragment component of this URI,
 * or {@code null} if the fragment is undefined
 */
 public String getRawFragment() {
 return fragment;
 }

 /**
 * Returns the decoded fragment component of this URI.
 *
 * The string returned by this method is equal to that returned by the
 * {@link #getRawFragment() getRawFragment} method except that all
 * sequences of escaped octets are <a href="#decode">decoded</a>. 
 *
 * @return The decoded fragment component of this URI,
 * or {@code null} if the fragment is undefined
 */
 public String getFragment() {
 String decoded = decodedFragment;
 if ((decoded == null) && (fragment != null)) {
 decodedFragment = decoded = decode(fragment, false);
 }
 return decoded;
 }

 // -- Equality, comparison, hash code, toString, and serialization --

 /**
 * Tests this URI for equality with another object.
 *
 * If the given object is not a URI then this method immediately
 * returns {@code false}.
 *
 * For two URIs to be considered equal requires that either both are
 * opaque or both are hierarchical. Their schemes must either both be
 * undefined or else be equal without regard to case. Their fragments
 * must either both be undefined or else be equal.
 *
 * For two opaque URIs to be considered equal, their scheme-specific
 * parts must be equal.
 *
 * For two hierarchical URIs to be considered equal, their paths must
 * be equal and their queries must either both be undefined or else be
 * equal. Their authorities must either both be undefined, or both be
 * registry-based, or both be server-based. If their authorities are
 * defined and are registry-based, then they must be equal. If their
 * authorities are defined and are server-based, then their hosts must be
 * equal without regard to case, their port numbers must be equal, and
 * their user-information components must be equal.
 *
 * When testing the user-information, path, query, fragment, authority,
 * or scheme-specific parts of two URIs for equality, the raw forms rather
 * than the encoded forms of these components are compared and the
 * hexadecimal digits of escaped octets are compared without regard to
 * case.
 *
 * This method satisfies the general contract of the {@link
 * java.lang.Object#equals(Object) Object.equals} method. 
 *
 * @param ob The object to which this object is to be compared
 *
 * @return {@code true} if, and only if, the given object is a URI that
 * is identical to this URI
 */
 public boolean equals(Object ob) {
 if (ob == this)
 return true;
 if (!(ob instanceof URI that))
 return false;
 if (this.isOpaque() != that.isOpaque()) return false;
 if (!equalIgnoringCase(this.scheme, that.scheme)) return false;
 if (!equal(this.fragment, that.fragment)) return false;

 // Opaque
 if (this.isOpaque())
 return equal(this.schemeSpecificPart, that.schemeSpecificPart);

 // Hierarchical
 if (!equal(this.path, that.path)) return false;
 if (!equal(this.query, that.query)) return false;

 // Authorities
 if (this.authority == that.authority) return true;
 if (this.host != null) {
 // Server-based
 if (!equal(this.userInfo, that.userInfo)) return false;
 if (!equalIgnoringCase(this.host, that.host)) return false;
 if (this.port != that.port) return false;
 } else if (this.authority != null) {
 // Registry-based
 if (!equal(this.authority, that.authority)) return false;
 } else if (this.authority != that.authority) {
 return false;
 }

 return true;
 }

 /**
 * Returns a hash-code value for this URI. The hash code is based upon all
 * of the URI's components, and satisfies the general contract of the
 * {@link java.lang.Object#hashCode() Object.hashCode} method.
 *
 * @return A hash-code value for this URI
 */
 public int hashCode() {
 int h = hash;
 if (h == 0) {
 h = hashIgnoringCase(0, scheme);
 h = hash(h, fragment);
 if (isOpaque()) {
 h = hash(h, schemeSpecificPart);
 } else {
 h = hash(h, path);
 h = hash(h, query);
 if (host != null) {
 h = hash(h, userInfo);
 h = hashIgnoringCase(h, host);
 h += 1949 * port;
 } else {
 h = hash(h, authority);
 }
--> --------------------

--> maximum size reached

--> --------------------

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