/*

 * Copyright (c) 1995, 2008, 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.InputStream;

/**

 * Class <code>URL</code> represents a Uniform Resource

 * Locator, a pointer to a "resource" on the World

 * Wide Web. A resource can be something as simple as a file or a

 * directory, or it can be a reference to a more complicated object,

 * such as a query to a database or to a search engine. More

 * information on the types of URLs and their formats can be found at:

 * <blockquote>

 *     <a href="http://www.socs.uts.edu.au/MosaicDocs-old/url-primer.html">

 *    <i>http://www.socs.uts.edu.au/MosaicDocs-old/url-primer.html</i></a>

 * </blockquote>

 * <p>

 * In general, a URL can be broken into several parts. The previous

 * example of a URL indicates that the protocol to use is

 * <code>http</code> (HyperText Transfer Protocol) and that the

 * information resides on a host machine named

 * <code>www.socs.uts.edu.au</code>. The information on that host

 * machine is named <code>/MosaicDocs-old/url-primer.html</code>. The exact

 * meaning of this name on the host machine is both protocol

 * dependent and host dependent. The information normally resides in

 * a file, but it could be generated on the fly. This component of

 * the URL is called the <i>path</i> component.

 * <p>

 * A URL can optionally specify a "port", which is the

 * port number to which the TCP connection is made on the remote host

 * machine. If the port is not specified, the default port for

 * the protocol is used instead. For example, the default port for

 * <code>http</code> is <code>80</code>. An alternative port could be

 * specified as:

 * <blockquote><pre>

 *     http://www.socs.uts.edu.au:80/MosaicDocs-old/url-primer.html

 * </pre></blockquote>

 * <p>

 * The syntax of <code>URL</code> is defined by  <a

 * href="http://www.ietf.org/rfc/rfc2396.txt"><i>RFC&nbsp;2396: Uniform

 * Resource Identifiers (URI): Generic Syntax</i></a>, amended by <a

 * href="http://www.ietf.org/rfc/rfc2732.txt"><i>RFC&nbsp;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>.

 * <p>

 * A URL may have appended to it a "fragment", also known

 * as a "ref" or a "reference". The fragment is indicated by the sharp

 * sign character "#" followed by more characters. For example,

 * <blockquote><pre>

 *     http://java.sun.com/index.html#chapter1

 * </pre></blockquote>

 * <p>

 * This fragment is not technically part of the URL. Rather, it

 * indicates that after the specified resource is retrieved, the

 * application is specifically interested in that part of the

 * document that has the tag <code>chapter1</code> attached to it. The

 * meaning of a tag is resource specific.

 * <p>

 * An application can also specify a "relative URL",

 * which contains only enough information to reach the resource

 * relative to another URL. Relative URLs are frequently used within

 * HTML pages. For example, if the contents of the URL:

 * <blockquote><pre>

 *     http://java.sun.com/index.html

 * </pre></blockquote>

 * contained within it the relative URL:

 * <blockquote><pre>

 *     FAQ.html

 * </pre></blockquote>

 * it would be a shorthand for:

 * <blockquote><pre>

 *     http://java.sun.com/FAQ.html

 * </pre></blockquote>

 * <p>

 * The relative URL need not specify all the components of a URL. If

 * the protocol, host name, or port number is missing, the value is

 * inherited from the fully specified URL. The file component must be

 * specified. The optional fragment is not inherited.

 * <p>

 * The URL class does not itself encode or decode any URL components

 * according to the escaping mechanism defined in RFC2396. It is the

 * responsibility of the caller to encode any fields, which need to be

 * escaped prior to calling URL, and also to decode any escaped fields,

 * that are returned from URL. Furthermore, because URL has no knowledge

 * of URL escaping, it does not recognise equivalence between the encoded

 * or decoded form of the same URL. For example, the two URLs:<br>

 * <pre>    http://foo.com/hello world/ and http://foo.com/hello%20world</pre>

 * would be considered not equal to each other.

 * <p>

 * Note, the {@link java.net.URI} class does perform escaping of its

 * component fields in certain circumstances. The recommended way

 * to manage the encoding and decoding of URLs is to use {@link java.net.URI},

 * and to convert between these two classes using {@link #toURI()} and

 * {@link URI#toURL()}.

 * <p>

 * The {@link URLEncoder} and {@link URLDecoder} classes can also be

 * used, but only for HTML form encoding, which is not the same

 * as the encoding scheme defined in RFC2396.

 *

 * @author  James Gosling

 * @since JDK1.0

 */

public final class URL implements java.io.Serializable {

    static final long serialVersionUID = -7627629688361524110L;

    /**

     * The property which specifies the package prefix list to be scanned

     * for protocol handlers.  The value of this property (if any) should

     * be a vertical bar delimited list of package names to search through

     * for a protocol handler to load.  The policy of this class is that

     * all protocol handlers will be in a class called <protocolname>.Handler,

     * and each package in the list is examined in turn for a matching

     * handler.  If none are found (or the property is not specified), the

     * default package prefix, sun.net.www.protocol, is used.  The search

     * proceeds from the first package in the list to the last and stops

     * when a match is found.

     */

    private static final String protocolPathProp = "java.protocol.handler.pkgs";

    /**

     * The protocol to use (ftp, http, nntp, ... etc.) .

     * @serial

     */

    private String protocol;

    /**

     * The host name to connect to.

     * @serial

     */

    private String host;

    /**

     * The protocol port to connect to.

     * @serial

     */

    private int port = -1;

    /**

     * The specified file name on that host. <code>file</code> is

     * defined as <code>path[?query]</code>

     * @serial

     */

    private String file;

    /**

     * The query part of this URL.

     */

    private transient String query;

    /**

     * The authority part of this URL.

     * @serial

     */

    private String authority;

    /**

     * The path part of this URL.

     */

    private transient String path;

    /**

     * The userinfo part of this URL.

     */

    private transient String userInfo;

    /**

     * # reference.

     * @serial

     */

    private String ref;

    /**

     * The host's IP address, used in equals and hashCode.

     * Computed on demand. An uninitialized or unknown hostAddress is null.

     */

    transient Object hostAddress;

    /**

     * The URLStreamHandler for this URL.

     */

    transient URLStreamHandler handler;

    /* Our hash code.

     * @serial

     */

    private int hashCode = -1;

    /**

     * Creates a <code>URL</code> object from the specified

     * <code>protocol</code>, <code>host</code>, <code>port</code>

     * number, and <code>file</code>.<p>

     *

     * <code>host</code> can be expressed as a host name or a literal

     * IP address. If IPv6 literal address is used, it should be

     * enclosed in square brackets (<tt>'['</tt> and <tt>']'</tt>), as

     * specified by <a

     * href="http://www.ietf.org/rfc/rfc2732.txt">RFC&nbsp;2732</a>;

     * However, the literal IPv6 address format defined in <a

     * href="http://www.ietf.org/rfc/rfc2373.txt"><i>RFC&nbsp;2373: IP

     * Version 6 Addressing Architecture</i></a> is also accepted.<p>

     *

     * Specifying a <code>port</code> number of <code>-1</code>

     * indicates that the URL should use the default port for the

     * protocol.<p>

     *

     * If this is the first URL object being created with the specified

     * protocol, a <i>stream protocol handler</i> object, an instance of

     * class <code>URLStreamHandler</code>, is created for that protocol:

     * <ol>

     * <li>If the application has previously set up an instance of

     *     <code>URLStreamHandlerFactory</code> as the stream handler factory,

     *     then the <code>createURLStreamHandler</code> method of that instance

     *     is called with the protocol string as an argument to create the

     *     stream protocol handler.

     * <li>If no <code>URLStreamHandlerFactory</code> has yet been set up,

     *     or if the factory's <code>createURLStreamHandler</code> method

     *     returns <code>null</code>, then the constructor finds the

     *     value of the system property:

     *     <blockquote><pre>

     *         java.protocol.handler.pkgs

     *     </pre></blockquote>

     *     If the value of that system property is not <code>null</code>,

     *     it is interpreted as a list of packages separated by a vertical

     *     slash character '<code>|</code>'. The constructor tries to load

     *     the class named:

     *     <blockquote><pre>

     *         &lt;<i>package</i>&gt;.&lt;<i>protocol</i>&gt;.Handler

     *     </pre></blockquote>

     *     where &lt;<i>package</i>&gt; is replaced by the name of the package

     *     and &lt;<i>protocol</i>&gt; is replaced by the name of the protocol.

     *     If this class does not exist, or if the class exists but it is not

     *     a subclass of <code>URLStreamHandler</code>, then the next package

     *     in the list is tried.

     * <li>If the previous step fails to find a protocol handler, then the

     *     constructor tries to load from a system default package.

     *     <blockquote><pre>

     *         &lt;<i>system default package</i>&gt;.&lt;<i>protocol</i>&gt;.Handler

     *     </pre></blockquote>

     *     If this class does not exist, or if the class exists but it is not a

     *     subclass of <code>URLStreamHandler</code>, then a

     *     <code>MalformedURLException</code> is thrown.

     * </ol>

     *

     * <p>Protocol handlers for the following protocols are guaranteed

     * to exist on the search path :-

     * <blockquote><pre>

     *     http, https, ftp, file, and jar

     * </pre></blockquote>

     * Protocol handlers for additional protocols may also be

     * available.

     *

     * <p>No validation of the inputs is performed by this constructor.

     *

     * @param      protocol   the name of the protocol to use.

     * @param      host       the name of the host.

     * @param      port       the port number on the host.

     * @param      file       the file on the host

     * @exception  MalformedURLException  if an unknown protocol is specified.

     * @see        java.lang.System#getProperty(java.lang.String)

     * @see        java.net.URL#setURLStreamHandlerFactory(

     *                  java.net.URLStreamHandlerFactory)

     * @see        java.net.URLStreamHandler

     * @see        java.net.URLStreamHandlerFactory#createURLStreamHandler(

     *                  java.lang.String)

     */

    public URL(String protocol, String host, int port, String file)

        throws MalformedURLException

    {

        this(protocol, host, port, file, null);

    }

    /**

     * Creates a URL from the specified <code>protocol</code>

     * name, <code>host</code> name, and <code>file</code> name. The

     * default port for the specified protocol is used.

     * <p>

     * This method is equivalent to calling the four-argument

     * constructor with the arguments being <code>protocol</code>,

     * <code>host</code>, <code>-1</code>, and <code>file</code>.

     *

     * No validation of the inputs is performed by this constructor.

     *

     * @param      protocol   the name of the protocol to use.

     * @param      host       the name of the host.

     * @param      file       the file on the host.

     * @exception  MalformedURLException  if an unknown protocol is specified.

     * @see        java.net.URL#URL(java.lang.String, java.lang.String,

     *                  int, java.lang.String)

     */

    public URL(String protocol, String host, String file)

            throws MalformedURLException {

        this(protocol, host, -1, file);

    }

    /**

     * Creates a <code>URL</code> object from the specified

     * <code>protocol</code>, <code>host</code>, <code>port</code>

     * number, <code>file</code>, and <code>handler</code>. Specifying

     * a <code>port</code> number of <code>-1</code> indicates that

     * the URL should use the default port for the protocol. Specifying

     * a <code>handler</code> of <code>null</code> indicates that the URL

     * should use a default stream handler for the protocol, as outlined

     * for:

     *     java.net.URL#URL(java.lang.String, java.lang.String, int,

     *                      java.lang.String)

     *

     * <p>If the handler is not null and there is a security manager,

     * the security manager's <code>checkPermission</code>

     * method is called with a

     * <code>NetPermission("specifyStreamHandler")</code> permission.

     * This may result in a SecurityException.

     *

     * No validation of the inputs is performed by this constructor.

     *

     * @param      protocol   the name of the protocol to use.

     * @param      host       the name of the host.

     * @param      port       the port number on the host.

     * @param      file       the file on the host

     * @param      handler    the stream handler for the URL.

     * @exception  MalformedURLException  if an unknown protocol is specified.

     * @exception  SecurityException

     *        if a security manager exists and its

     *        <code>checkPermission</code> method doesn't allow

     *        specifying a stream handler explicitly.

     * @see        java.lang.System#getProperty(java.lang.String)

     * @see        java.net.URL#setURLStreamHandlerFactory(

     *                  java.net.URLStreamHandlerFactory)

     * @see        java.net.URLStreamHandler

     * @see        java.net.URLStreamHandlerFactory#createURLStreamHandler(

     *                  java.lang.String)

     * @see        SecurityManager#checkPermission

     * @see        java.net.NetPermission

     */

    public URL(String protocol, String host, int port, String file,

               URLStreamHandler handler) throws MalformedURLException {

        if (handler != null) {

            throw new SecurityException();

        }

        protocol = protocol.toLowerCase();

        this.protocol = protocol;

        if (host != null) {

            /**

             * if host is a literal IPv6 address,

             * we will make it conform to RFC 2732

             */

            if (host.indexOf(':') >= 0 && !host.startsWith("[")) {

                host = "["+host+"]";

            }

            this.host = host;

            if (port < -1) {

                throw new MalformedURLException("Invalid port number :" +

                                                    port);

            }

            this.port = port;

            authority = (port == -1) ? host : host + ":" + port;

        }

        Parts parts = new Parts(file);

        path = parts.getPath();

        query = parts.getQuery();

        if (query != null) {

            this.file = path + "?" + query;

        } else {

            this.file = path;

        }

        ref = parts.getRef();

        // Note: we don't do validation of the URL here. Too risky to change

        // right now, but worth considering for future reference. -br

        if (handler == null &&

            (handler = getURLStreamHandler(protocol)) == null) {

            throw new MalformedURLException("unknown protocol: " + protocol);

        }

        this.handler = handler;

    }

    /**

     * Creates a <code>URL</code> object from the <code>String</code>

     * representation.

     * <p>

     * This constructor is equivalent to a call to the two-argument

     * constructor with a <code>null</code> first argument.

     *

     * @param      spec   the <code>String</code> to parse as a URL.

     * @exception  MalformedURLException  if no protocol is specified, or an

     *               unknown protocol is found, or <tt>spec</tt> is <tt>null</tt>.

     * @see        java.net.URL#URL(java.net.URL, java.lang.String)

     */

    public URL(String spec) throws MalformedURLException {

        this(null, spec);

    }

    /**

     * Creates a URL by parsing the given spec within a specified context.

     *

     * The new URL is created from the given context URL and the spec

     * argument as described in

     * RFC2396 "Uniform Resource Identifiers : Generic * Syntax" :

     * <blockquote><pre>

     *          <scheme>://<authority><path>?<query>#<fragment>

     * </pre></blockquote>

     * The reference is parsed into the scheme, authority, path, query and

     * fragment parts. If the path component is empty and the scheme,

     * authority, and query components are undefined, then the new URL is a

     * reference to the current document. Otherwise, the fragment and query

     * parts present in the spec are used in the new URL.

     * <p>

     * If the scheme component is defined in the given spec and does not match

     * the scheme of the context, then the new URL is created as an absolute

     * URL based on the spec alone. Otherwise the scheme component is inherited

     * from the context URL.

     * <p>

     * If the authority component is present in the spec then the spec is

     * treated as absolute and the spec authority and path will replace the

     * context authority and path. If the authority component is absent in the

     * spec then the authority of the new URL will be inherited from the

     * context.

     * <p>

     * If the spec's path component begins with a slash character

     * "/" then the

     * path is treated as absolute and the spec path replaces the context path.

     * <p>

     * Otherwise, the path is treated as a relative path and is appended to the

     * context path, as described in RFC2396. Also, in this case,

     * the path is canonicalized through the removal of directory

     * changes made by occurences of ".." and ".".

     * <p>

     * For a more detailed description of URL parsing, refer to RFC2396.

     *

     * @param      context   the context in which to parse the specification.

     * @param      spec      the <code>String</code> to parse as a URL.

     * @exception  MalformedURLException  if no protocol is specified, or an

     *               unknown protocol is found, or <tt>spec</tt> is <tt>null</tt>.

     * @see        java.net.URL#URL(java.lang.String, java.lang.String,

     *                  int, java.lang.String)

     * @see        java.net.URLStreamHandler

     * @see        java.net.URLStreamHandler#parseURL(java.net.URL,

     *                  java.lang.String, int, int)

     */

    public URL(URL context, String spec) throws MalformedURLException {

        this(context, spec, null);

    }

    /**

     * Creates a URL by parsing the given spec with the specified handler

     * within a specified context. If the handler is null, the parsing

     * occurs as with the two argument constructor.

     *

     * @param      context   the context in which to parse the specification.

     * @param      spec      the <code>String</code> to parse as a URL.

     * @param      handler   the stream handler for the URL.

     * @exception  MalformedURLException  if no protocol is specified, or an

     *               unknown protocol is found, or <tt>spec</tt> is <tt>null</tt>.

     * @exception  SecurityException

     *        if a security manager exists and its

     *        <code>checkPermission</code> method doesn't allow

     *        specifying a stream handler.

     * @see        java.net.URL#URL(java.lang.String, java.lang.String,

     *                  int, java.lang.String)

     * @see        java.net.URLStreamHandler

     * @see        java.net.URLStreamHandler#parseURL(java.net.URL,

     *                  java.lang.String, int, int)

     */

    public URL(URL context, String spec, URLStreamHandler handler)

        throws MalformedURLException

    {

        String original = spec;

        int i, limit, c;

        int start = 0;

        String newProtocol = null;

        boolean aRef=false;

        boolean isRelative = false;

        // Check for permission to specify a handler

        if (handler != null) {

            throw new SecurityException();

        }

        try {

            limit = spec.length();

            while ((limit > 0) && (spec.charAt(limit - 1) <= ' ')) {

                limit--;        //eliminate trailing whitespace

            }

            while ((start < limit) && (spec.charAt(start) <= ' ')) {

                start++;        // eliminate leading whitespace

            }

            if (spec.regionMatches(true, start, "url:", 0, 4)) {

                start += 4;

            }

            if (start < spec.length() && spec.charAt(start) == '#') {

                /* we're assuming this is a ref relative to the context URL.

                 * This means protocols cannot start w/ '#', but we must parse

                 * ref URL's like: "hello:there" w/ a ':' in them.

                 */

                aRef=true;

            }

            for (i = start ; !aRef && (i < limit) &&

                     ((c = spec.charAt(i)) != '/') ; i++) {

                if (c == ':') {

                    String s = spec.substring(start, i).toLowerCase();

                    if (isValidProtocol(s)) {

                        newProtocol = s;

                        start = i + 1;

                    }

                    break;

                }

            }

            // Only use our context if the protocols match.

            protocol = newProtocol;

            if ((context != null) && ((newProtocol == null) ||

                            newProtocol.equalsIgnoreCase(context.protocol))) {

                // inherit the protocol handler from the context

                // if not specified to the constructor

                if (handler == null) {

                    handler = context.handler;

                }

                // If the context is a hierarchical URL scheme and the spec

                // contains a matching scheme then maintain backwards

                // compatibility and treat it as if the spec didn't contain

                // the scheme; see 5.2.3 of RFC2396

                if (context.path != null && context.path.startsWith("/"))

                    newProtocol = null;

                if (newProtocol == null) {

                    protocol = context.protocol;

                    authority = context.authority;

                    userInfo = context.userInfo;

                    host = context.host;

                    port = context.port;

                    file = context.file;

                    path = context.path;

                    isRelative = true;

                }

            }

            if (protocol == null) {

                throw new MalformedURLException("no protocol: "+original);

            }

            // Get the protocol handler if not specified or the protocol

            // of the context could not be used

            if (handler == null &&

                (handler = getURLStreamHandler(protocol)) == null) {

                throw new MalformedURLException("unknown protocol: "+protocol);

            }

            this.handler = handler;

            i = spec.indexOf('#', start);

            if (i >= 0) {

//thrw(protocol + " hnd: " + handler.getClass().getName() + " i: " + i);

                ref = spec.substring(i + 1, limit);

                limit = i;

            }

            /*

             * Handle special case inheritance of query and fragment

             * implied by RFC2396 section 5.2.2.

             */

            if (isRelative && start == limit) {

                query = context.query;

                if (ref == null) {

                    ref = context.ref;

                }

            }

            handler.parseURL(this, spec, start, limit);

        } catch(MalformedURLException e) {

            throw e;

        } catch(Exception e) {

            MalformedURLException exception = new MalformedURLException(e.getMessage());

            exception.initCause(e);

            throw exception;

        }

    }

    /*

     * Returns true if specified string is a valid protocol name.

     */

    private boolean isValidProtocol(String protocol) {

        int len = protocol.length();

        if (len < 1)

            return false;

        char c = protocol.charAt(0);

        if (!Character.isLetter(c))

            return false;

        for (int i = 1; i < len; i++) {

            c = protocol.charAt(i);

            if (!Character.isLetterOrDigit(c) && c != '.' && c != '+' &&

                c != '-') {

                return false;

            }

        }

        return true;

    }

    /**

     * Sets the fields of the URL. This is not a public method so that

     * only URLStreamHandlers can modify URL fields. URLs are

     * otherwise constant.

     *

     * @param protocol the name of the protocol to use

     * @param host the name of the host

       @param port the port number on the host

     * @param file the file on the host

     * @param ref the internal reference in the URL

     */

    protected void set(String protocol, String host,

                       int port, String file, String ref) {

        synchronized (this) {

            this.protocol = protocol;

            this.host = host;

            authority = port == -1 ? host : host + ":" + port;

            this.port = port;

            this.file = file;

            this.ref = ref;

            /* This is very important. We must recompute this after the

             * URL has been changed. */

            hashCode = -1;

            hostAddress = null;

            int q = file.lastIndexOf('?');

            if (q != -1) {

                query = file.substring(q+1);

                path = file.substring(0, q);

            } else

                path = file;

        }

    }

    /**

     * Sets the specified 8 fields of the URL. This is not a public method so

     * that only URLStreamHandlers can modify URL fields. URLs are otherwise

     * constant.

     *

     * @param protocol the name of the protocol to use

     * @param host the name of the host

     * @param port the port number on the host

     * @param authority the authority part for the url

     * @param userInfo the username and password

     * @param path the file on the host

     * @param ref the internal reference in the URL

     * @param query the query part of this URL

     * @since 1.3

     */

    protected void set(String protocol, String host, int port,

                       String authority, String userInfo, String path,

                       String query, String ref) {

        synchronized (this) {

            this.protocol = protocol;

            this.host = host;

            this.port = port;

            this.file = query == null ? path : path + "?" + query;

            this.userInfo = userInfo;

            this.path = path;

            this.ref = ref;

            /* This is very important. We must recompute this after the

             * URL has been changed. */

            hashCode = -1;

            hostAddress = null;

            this.query = query;

            this.authority = authority;

        }

    }

    /**

     * Gets the query part of this <code>URL</code>.

     *

     * @return  the query part of this <code>URL</code>,

     * or <CODE>null</CODE> if one does not exist

     * @since 1.3

     */

    public String getQuery() {

        return query;

    }

    /**

     * Gets the path part of this <code>URL</code>.

     *

     * @return  the path part of this <code>URL</code>, or an

     * empty string if one does not exist

     * @since 1.3

     */

    public String getPath() {

        return path;

    }

    /**

     * Gets the userInfo part of this <code>URL</code>.

     *

     * @return  the userInfo part of this <code>URL</code>, or

     * <CODE>null</CODE> if one does not exist

     * @since 1.3

     */

    public String getUserInfo() {

        return userInfo;

    }

    /**

     * Gets the authority part of this <code>URL</code>.

     *

     * @return  the authority part of this <code>URL</code>

     * @since 1.3

     */

    public String getAuthority() {

        return authority;

    }

    /**

     * Gets the port number of this <code>URL</code>.

     *

     * @return  the port number, or -1 if the port is not set

     */

    public int getPort() {

        return port;

    }

    /**

     * Gets the default port number of the protocol associated

     * with this <code>URL</code>. If the URL scheme or the URLStreamHandler

     * for the URL do not define a default port number,

     * then -1 is returned.

     *

     * @return  the port number

     * @since 1.4

     */

    public int getDefaultPort() {

        return handler.getDefaultPort();

    }

    /**

     * Gets the protocol name of this <code>URL</code>.

     *

     * @return  the protocol of this <code>URL</code>.

     */

    public String getProtocol() {

        return protocol;

    }

    /**

     * Gets the host name of this <code>URL</code>, if applicable.

     * The format of the host conforms to RFC 2732, i.e. for a

     * literal IPv6 address, this method will return the IPv6 address

     * enclosed in square brackets (<tt>'['</tt> and <tt>']'</tt>).

     *

     * @return  the host name of this <code>URL</code>.

     */

    public String getHost() {

        return host;

    }

    /**

     * Gets the file name of this <code>URL</code>.

     * The returned file portion will be

     * the same as <CODE>getPath()</CODE>, plus the concatenation of

     * the value of <CODE>getQuery()</CODE>, if any. If there is

     * no query portion, this method and <CODE>getPath()</CODE> will

     * return identical results.

     *

     * @return  the file name of this <code>URL</code>,

     * or an empty string if one does not exist

     */

    public String getFile() {

        return file;

    }

    /**

     * Gets the anchor (also known as the "reference") of this

     * <code>URL</code>.

     *

     * @return  the anchor (also known as the "reference") of this

     *          <code>URL</code>, or <CODE>null</CODE> if one does not exist

     */

    public String getRef() {

        return ref;

    }

    /**

     * Compares this URL for equality with another object.<p>

     *

     * If the given object is not a URL then this method immediately returns

     * <code>false</code>.<p>

     *

     * Two URL objects are equal if they have the same protocol, reference

     * equivalent hosts, have the same port number on the host, and the same

     * file and fragment of the file.<p>

     *

     * Two hosts are considered equivalent if both host names can be resolved

     * into the same IP addresses; else if either host name can't be

     * resolved, the host names must be equal without regard to case; or both

     * host names equal to null.<p>

     *

     * Since hosts comparison requires name resolution, this operation is a

     * blocking operation. <p>

     *

     * Note: The defined behavior for <code>equals</code> is known to

     * be inconsistent with virtual hosting in HTTP.

     *

     * @param   obj   the URL to compare against.

     * @return  <code>true</code> if the objects are the same;

     *          <code>false</code> otherwise.

     */

    public boolean equals(Object obj) {

        if (!(obj instanceof URL))

            return false;

        URL u2 = (URL)obj;

        return handler.equals(this, u2);

    }

    /**

     * Creates an integer suitable for hash table indexing.<p>

     *

     * The hash code is based upon all the URL components relevant for URL

     * comparison. As such, this operation is a blocking operation.<p>

     *

     * @return  a hash code for this <code>URL</code>.

     */

    public synchronized int hashCode() {

        if (hashCode != -1)

            return hashCode;

        hashCode = handler.hashCode(this);

        return hashCode;

    }

    /**

     * Compares two URLs, excluding the fragment component.<p>

     *

     * Returns <code>true</code> if this <code>URL</code> and the

     * <code>other</code> argument are equal without taking the

     * fragment component into consideration.

     *

     * @param   other   the <code>URL</code> to compare against.

     * @return  <code>true</code> if they reference the same remote object;

     *          <code>false</code> otherwise.

     */

    public boolean sameFile(URL other) {

        return handler.sameFile(this, other);

    }

    /**

     * Constructs a string representation of this <code>URL</code>. The

     * string is created by calling the <code>toExternalForm</code>

     * method of the stream protocol handler for this object.

     *

     * @return  a string representation of this object.

     * @see     java.net.URL#URL(java.lang.String, java.lang.String, int,

     *                  java.lang.String)

     * @see     java.net.URLStreamHandler#toExternalForm(java.net.URL)

     */

    public String toString() {

        return toExternalForm();

    }

    /**

     * Constructs a string representation of this <code>URL</code>. The

     * string is created by calling the <code>toExternalForm</code>

     * method of the stream protocol handler for this object.

     *

     * @return  a string representation of this object.

     * @see     java.net.URL#URL(java.lang.String, java.lang.String,

     *                  int, java.lang.String)

     * @see     java.net.URLStreamHandler#toExternalForm(java.net.URL)

     */

    public String toExternalForm() {

        return handler.toExternalForm(this);

    }

    /**

     * Returns a {@link java.net.URLConnection URLConnection} instance that

     * represents a connection to the remote object referred to by the

     * {@code URL}.

     *

     * <P>A new instance of {@linkplain java.net.URLConnection URLConnection} is

     * created every time when invoking the

     * {@linkplain java.net.URLStreamHandler#openConnection(URL)

     * URLStreamHandler.openConnection(URL)} method of the protocol handler for

     * this URL.</P>

     *

     * <P>It should be noted that a URLConnection instance does not establish

     * the actual network connection on creation. This will happen only when

     * calling {@linkplain java.net.URLConnection#connect() URLConnection.connect()}.</P>

     *

     * <P>If for the URL's protocol (such as HTTP or JAR), there

     * exists a public, specialized URLConnection subclass belonging

     * to one of the following packages or one of their subpackages:

     * java.lang, java.io, java.util, java.net, the connection

     * returned will be of that subclass. For example, for HTTP an

     * HttpURLConnection will be returned, and for JAR a

     * JarURLConnection will be returned.</P>

     *

     * @return     a {@link java.net.URLConnection URLConnection} linking

     *             to the URL.

     * @exception  IOException  if an I/O exception occurs.

     * @see        java.net.URL#URL(java.lang.String, java.lang.String,

     *             int, java.lang.String)

     */

//    public URLConnection openConnection() throws java.io.IOException {

//        return handler.openConnection(this);

//    }

    /**

     * Opens a connection to this <code>URL</code> and returns an

     * <code>InputStream</code> for reading from that connection. This

     * method is a shorthand for:

     * <blockquote><pre>

     *     openConnection().getInputStream()

     * </pre></blockquote>

     *

     * @return     an input stream for reading from the URL connection.

     * @exception  IOException  if an I/O exception occurs.

     * @see        java.net.URL#openConnection()

     * @see        java.net.URLConnection#getInputStream()

     */

    public final InputStream openStream() throws java.io.IOException {

        throw new IOException();

//        return openConnection().getInputStream();

    }

    /**

     * Gets the contents of this URL. This method is a shorthand for:

     * <blockquote><pre>

     *     openConnection().getContent()

     * </pre></blockquote>

     *

     * @return     the contents of this URL.

     * @exception  IOException  if an I/O exception occurs.

     * @see        java.net.URLConnection#getContent()

     */

    public final Object getContent() throws java.io.IOException {

        throw new IOException();

//        return openConnection().getContent();

    }

    /**

     * Gets the contents of this URL. This method is a shorthand for:

     * <blockquote><pre>

     *     openConnection().getContent(Class[])

     * </pre></blockquote>

     *

     * @param classes an array of Java types

     * @return     the content object of this URL that is the first match of

     *               the types specified in the classes array.

     *               null if none of the requested types are supported.

     * @exception  IOException  if an I/O exception occurs.

     * @see        java.net.URLConnection#getContent(Class[])

     * @since 1.3

     */

    public final Object getContent(Class[] classes)

    throws java.io.IOException {

        throw new IOException();

//        return openConnection().getContent(classes);

    }

    static URLStreamHandler getURLStreamHandler(String protocol) {

        URLStreamHandler universal = new URLStreamHandler() {};

        return universal;