1 /*
   2  * Copyright (c) 1995, 2013, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package java.net;
  27 
  28 import java.io.IOException;
  29 import java.io.InputStream;
  30 import java.util.Hashtable;
  31 import java.util.StringTokenizer;
  32 import sun.security.util.SecurityConstants;
  33 
  34 /**
  35  * Class {@code URL} represents a Uniform Resource
  36  * Locator, a pointer to a "resource" on the World
  37  * Wide Web. A resource can be something as simple as a file or a
  38  * directory, or it can be a reference to a more complicated object,
  39  * such as a query to a database or to a search engine. More
  40  * information on the types of URLs and their formats can be found at:
  41  * <a href=
  42  * "http://web.archive.org/web/20051219043731/http://archive.ncsa.uiuc.edu/SDG/Software/Mosaic/Demo/url-primer.html">
  43  * <i>Types of URL</i></a>
  44  * <p>
  45  * In general, a URL can be broken into several parts. Consider the
  46  * following example:
  47  * <blockquote><pre>
  48  *     http://www.example.com/docs/resource1.html
  49  * </pre></blockquote>
  50  * <p>
  51  * The URL above indicates that the protocol to use is
  52  * {@code http} (HyperText Transfer Protocol) and that the
  53  * information resides on a host machine named
  54  * {@code www.example.com}. The information on that host
  55  * machine is named {@code /docs/resource1.html}. The exact
  56  * meaning of this name on the host machine is both protocol
  57  * dependent and host dependent. The information normally resides in
  58  * a file, but it could be generated on the fly. This component of
  59  * the URL is called the <i>path</i> component.
  60  * <p>
  61  * A URL can optionally specify a "port", which is the
  62  * port number to which the TCP connection is made on the remote host
  63  * machine. If the port is not specified, the default port for
  64  * the protocol is used instead. For example, the default port for
  65  * {@code http} is {@code 80}. An alternative port could be
  66  * specified as:
  67  * <blockquote><pre>
  68  *     http://www.example.com:1080/docs/resource1.html
  69  * </pre></blockquote>
  70  * <p>
  71  * The syntax of {@code URL} is defined by  <a
  72  * href="http://www.ietf.org/rfc/rfc2396.txt"><i>RFC&nbsp;2396: Uniform
  73  * Resource Identifiers (URI): Generic Syntax</i></a>, amended by <a
  74  * href="http://www.ietf.org/rfc/rfc2732.txt"><i>RFC&nbsp;2732: Format for
  75  * Literal IPv6 Addresses in URLs</i></a>. The Literal IPv6 address format
  76  * also supports scope_ids. The syntax and usage of scope_ids is described
  77  * <a href="Inet6Address.html#scoped">here</a>.
  78  * <p>
  79  * A URL may have appended to it a "fragment", also known
  80  * as a "ref" or a "reference". The fragment is indicated by the sharp
  81  * sign character "#" followed by more characters. For example,
  82  * <blockquote><pre>
  83  *     http://java.sun.com/index.html#chapter1
  84  * </pre></blockquote>
  85  * <p>
  86  * This fragment is not technically part of the URL. Rather, it
  87  * indicates that after the specified resource is retrieved, the
  88  * application is specifically interested in that part of the
  89  * document that has the tag {@code chapter1} attached to it. The
  90  * meaning of a tag is resource specific.
  91  * <p>
  92  * An application can also specify a "relative URL",
  93  * which contains only enough information to reach the resource
  94  * relative to another URL. Relative URLs are frequently used within
  95  * HTML pages. For example, if the contents of the URL:
  96  * <blockquote><pre>
  97  *     http://java.sun.com/index.html
  98  * </pre></blockquote>
  99  * contained within it the relative URL:
 100  * <blockquote><pre>
 101  *     FAQ.html
 102  * </pre></blockquote>
 103  * it would be a shorthand for:
 104  * <blockquote><pre>
 105  *     http://java.sun.com/FAQ.html
 106  * </pre></blockquote>
 107  * <p>
 108  * The relative URL need not specify all the components of a URL. If
 109  * the protocol, host name, or port number is missing, the value is
 110  * inherited from the fully specified URL. The file component must be
 111  * specified. The optional fragment is not inherited.
 112  * <p>
 113  * The URL class does not itself encode or decode any URL components
 114  * according to the escaping mechanism defined in RFC2396. It is the
 115  * responsibility of the caller to encode any fields, which need to be
 116  * escaped prior to calling URL, and also to decode any escaped fields,
 117  * that are returned from URL. Furthermore, because URL has no knowledge
 118  * of URL escaping, it does not recognise equivalence between the encoded
 119  * or decoded form of the same URL. For example, the two URLs:<br>
 120  * <pre>    http://foo.com/hello world/ and http://foo.com/hello%20world</pre>
 121  * would be considered not equal to each other.
 122  * <p>
 123  * Note, the {@link java.net.URI} class does perform escaping of its
 124  * component fields in certain circumstances. The recommended way
 125  * to manage the encoding and decoding of URLs is to use {@link java.net.URI},
 126  * and to convert between these two classes using {@link #toURI()} and
 127  * {@link URI#toURL()}.
 128  * <p>
 129  * The {@link URLEncoder} and {@link URLDecoder} classes can also be
 130  * used, but only for HTML form encoding, which is not the same
 131  * as the encoding scheme defined in RFC2396.
 132  *
 133  * @author  James Gosling
 134  * @since 1.0
 135  */
 136 public final class URL implements java.io.Serializable {
 137 
 138     static final long serialVersionUID = -7627629688361524110L;
 139 
 140     /**
 141      * The property which specifies the package prefix list to be scanned
 142      * for protocol handlers.  The value of this property (if any) should
 143      * be a vertical bar delimited list of package names to search through
 144      * for a protocol handler to load.  The policy of this class is that
 145      * all protocol handlers will be in a class called <protocolname>.Handler,
 146      * and each package in the list is examined in turn for a matching
 147      * handler.  If none are found (or the property is not specified), the
 148      * default package prefix, sun.net.www.protocol, is used.  The search
 149      * proceeds from the first package in the list to the last and stops
 150      * when a match is found.
 151      */
 152     private static final String protocolPathProp = "java.protocol.handler.pkgs";
 153 
 154     /**
 155      * The protocol to use (ftp, http, nntp, ... etc.) .
 156      * @serial
 157      */
 158     private String protocol;
 159 
 160     /**
 161      * The host name to connect to.
 162      * @serial
 163      */
 164     private String host;
 165 
 166     /**
 167      * The protocol port to connect to.
 168      * @serial
 169      */
 170     private int port = -1;
 171 
 172     /**
 173      * The specified file name on that host. {@code file} is
 174      * defined as {@code path[?query]}
 175      * @serial
 176      */
 177     private String file;
 178 
 179     /**
 180      * The query part of this URL.
 181      */
 182     private transient String query;
 183 
 184     /**
 185      * The authority part of this URL.
 186      * @serial
 187      */
 188     private String authority;
 189 
 190     /**
 191      * The path part of this URL.
 192      */
 193     private transient String path;
 194 
 195     /**
 196      * The userinfo part of this URL.
 197      */
 198     private transient String userInfo;
 199 
 200     /**
 201      * # reference.
 202      * @serial
 203      */
 204     private String ref;
 205 
 206     /**
 207      * The host's IP address, used in equals and hashCode.
 208      * Computed on demand. An uninitialized or unknown hostAddress is null.
 209      */
 210     transient InetAddress hostAddress;
 211 
 212     /**
 213      * The URLStreamHandler for this URL.
 214      */
 215     transient URLStreamHandler handler;
 216 
 217     /* Our hash code.
 218      * @serial
 219      */
 220     private int hashCode = -1;
 221 
 222     /**
 223      * Creates a {@code URL} object from the specified
 224      * {@code protocol}, {@code host}, {@code port}
 225      * number, and {@code file}.<p>
 226      *
 227      * {@code host} can be expressed as a host name or a literal
 228      * IP address. If IPv6 literal address is used, it should be
 229      * enclosed in square brackets ({@code '['} and {@code ']'}), as
 230      * specified by <a
 231      * href="http://www.ietf.org/rfc/rfc2732.txt">RFC&nbsp;2732</a>;
 232      * However, the literal IPv6 address format defined in <a
 233      * href="http://www.ietf.org/rfc/rfc2373.txt"><i>RFC&nbsp;2373: IP
 234      * Version 6 Addressing Architecture</i></a> is also accepted.<p>
 235      *
 236      * Specifying a {@code port} number of {@code -1}
 237      * indicates that the URL should use the default port for the
 238      * protocol.<p>
 239      *
 240      * If this is the first URL object being created with the specified
 241      * protocol, a <i>stream protocol handler</i> object, an instance of
 242      * class {@code URLStreamHandler}, is created for that protocol:
 243      * <ol>
 244      * <li>If the application has previously set up an instance of
 245      *     {@code URLStreamHandlerFactory} as the stream handler factory,
 246      *     then the {@code createURLStreamHandler} method of that instance
 247      *     is called with the protocol string as an argument to create the
 248      *     stream protocol handler.
 249      * <li>If no {@code URLStreamHandlerFactory} has yet been set up,
 250      *     or if the factory's {@code createURLStreamHandler} method
 251      *     returns {@code null}, then the constructor finds the
 252      *     value of the system property:
 253      *     <blockquote><pre>
 254      *         java.protocol.handler.pkgs
 255      *     </pre></blockquote>
 256      *     If the value of that system property is not {@code null},
 257      *     it is interpreted as a list of packages separated by a vertical
 258      *     slash character '{@code |}'. The constructor tries to load
 259      *     the class named:
 260      *     <blockquote><pre>
 261      *         &lt;<i>package</i>&gt;.&lt;<i>protocol</i>&gt;.Handler
 262      *     </pre></blockquote>
 263      *     where &lt;<i>package</i>&gt; is replaced by the name of the package
 264      *     and &lt;<i>protocol</i>&gt; is replaced by the name of the protocol.
 265      *     If this class does not exist, or if the class exists but it is not
 266      *     a subclass of {@code URLStreamHandler}, then the next package
 267      *     in the list is tried.
 268      * <li>If the previous step fails to find a protocol handler, then the
 269      *     constructor tries to load a built-in protocol handler.
 270      *     If this class does not exist, or if the class exists but it is not a
 271      *     subclass of {@code URLStreamHandler}, then a
 272      *     {@code MalformedURLException} is thrown.
 273      * </ol>
 274      *
 275      * <p>Protocol handlers for the following protocols are guaranteed
 276      * to exist on the search path :-
 277      * <blockquote><pre>
 278      *     http, https, file, and jar
 279      * </pre></blockquote>
 280      * Protocol handlers for additional protocols may also be
 281      * available.
 282      *
 283      * <p>No validation of the inputs is performed by this constructor.
 284      *
 285      * @param      protocol   the name of the protocol to use.
 286      * @param      host       the name of the host.
 287      * @param      port       the port number on the host.
 288      * @param      file       the file on the host
 289      * @exception  MalformedURLException  if an unknown protocol is specified.
 290      * @see        java.lang.System#getProperty(java.lang.String)
 291      * @see        java.net.URL#setURLStreamHandlerFactory(
 292      *                  java.net.URLStreamHandlerFactory)
 293      * @see        java.net.URLStreamHandler
 294      * @see        java.net.URLStreamHandlerFactory#createURLStreamHandler(
 295      *                  java.lang.String)
 296      */
 297     public URL(String protocol, String host, int port, String file)
 298         throws MalformedURLException
 299     {
 300         this(protocol, host, port, file, null);
 301     }
 302 
 303     /**
 304      * Creates a URL from the specified {@code protocol}
 305      * name, {@code host} name, and {@code file} name. The
 306      * default port for the specified protocol is used.
 307      * <p>
 308      * This method is equivalent to calling the four-argument
 309      * constructor with the arguments being {@code protocol},
 310      * {@code host}, {@code -1}, and {@code file}.
 311      *
 312      * No validation of the inputs is performed by this constructor.
 313      *
 314      * @param      protocol   the name of the protocol to use.
 315      * @param      host       the name of the host.
 316      * @param      file       the file on the host.
 317      * @exception  MalformedURLException  if an unknown protocol is specified.
 318      * @see        java.net.URL#URL(java.lang.String, java.lang.String,
 319      *                  int, java.lang.String)
 320      */
 321     public URL(String protocol, String host, String file)
 322             throws MalformedURLException {
 323         this(protocol, host, -1, file);
 324     }
 325 
 326     /**
 327      * Creates a {@code URL} object from the specified
 328      * {@code protocol}, {@code host}, {@code port}
 329      * number, {@code file}, and {@code handler}. Specifying
 330      * a {@code port} number of {@code -1} indicates that
 331      * the URL should use the default port for the protocol. Specifying
 332      * a {@code handler} of {@code null} indicates that the URL
 333      * should use a default stream handler for the protocol, as outlined
 334      * for:
 335      *     java.net.URL#URL(java.lang.String, java.lang.String, int,
 336      *                      java.lang.String)
 337      *
 338      * <p>If the handler is not null and there is a security manager,
 339      * the security manager's {@code checkPermission}
 340      * method is called with a
 341      * {@code NetPermission("specifyStreamHandler")} permission.
 342      * This may result in a SecurityException.
 343      *
 344      * No validation of the inputs is performed by this constructor.
 345      *
 346      * @param      protocol   the name of the protocol to use.
 347      * @param      host       the name of the host.
 348      * @param      port       the port number on the host.
 349      * @param      file       the file on the host
 350      * @param      handler    the stream handler for the URL.
 351      * @exception  MalformedURLException  if an unknown protocol is specified.
 352      * @exception  SecurityException
 353      *        if a security manager exists and its
 354      *        {@code checkPermission} method doesn't allow
 355      *        specifying a stream handler explicitly.
 356      * @see        java.lang.System#getProperty(java.lang.String)
 357      * @see        java.net.URL#setURLStreamHandlerFactory(
 358      *                  java.net.URLStreamHandlerFactory)
 359      * @see        java.net.URLStreamHandler
 360      * @see        java.net.URLStreamHandlerFactory#createURLStreamHandler(
 361      *                  java.lang.String)
 362      * @see        SecurityManager#checkPermission
 363      * @see        java.net.NetPermission
 364      */
 365     public URL(String protocol, String host, int port, String file,
 366                URLStreamHandler handler) throws MalformedURLException {
 367         if (handler != null) {
 368             SecurityManager sm = System.getSecurityManager();
 369             if (sm != null) {
 370                 // check for permission to specify a handler
 371                 checkSpecifyHandler(sm);
 372             }
 373         }
 374 
 375         protocol = protocol.toLowerCase();
 376         this.protocol = protocol;
 377         if (host != null) {
 378 
 379             /**
 380              * if host is a literal IPv6 address,
 381              * we will make it conform to RFC 2732
 382              */
 383             if (host.indexOf(':') >= 0 && !host.startsWith("[")) {
 384                 host = "["+host+"]";
 385             }
 386             this.host = host;
 387 
 388             if (port < -1) {
 389                 throw new MalformedURLException("Invalid port number :" +
 390                                                     port);
 391             }
 392             this.port = port;
 393             authority = (port == -1) ? host : host + ":" + port;
 394         }
 395 
 396         Parts parts = new Parts(file);
 397         path = parts.getPath();
 398         query = parts.getQuery();
 399 
 400         if (query != null) {
 401             this.file = path + "?" + query;
 402         } else {
 403             this.file = path;
 404         }
 405         ref = parts.getRef();
 406 
 407         // Note: we don't do validation of the URL here. Too risky to change
 408         // right now, but worth considering for future reference. -br
 409         if (handler == null &&
 410             (handler = getURLStreamHandler(protocol)) == null) {
 411             throw new MalformedURLException("unknown protocol: " + protocol);
 412         }
 413         this.handler = handler;
 414     }
 415 
 416     /**
 417      * Creates a {@code URL} object from the {@code String}
 418      * representation.
 419      * <p>
 420      * This constructor is equivalent to a call to the two-argument
 421      * constructor with a {@code null} first argument.
 422      *
 423      * @param      spec   the {@code String} to parse as a URL.
 424      * @exception  MalformedURLException  if no protocol is specified, or an
 425      *               unknown protocol is found, or {@code spec} is {@code null}.
 426      * @see        java.net.URL#URL(java.net.URL, java.lang.String)
 427      */
 428     public URL(String spec) throws MalformedURLException {
 429         this(null, spec);
 430     }
 431 
 432     /**
 433      * Creates a URL by parsing the given spec within a specified context.
 434      *
 435      * The new URL is created from the given context URL and the spec
 436      * argument as described in
 437      * RFC2396 &quot;Uniform Resource Identifiers : Generic * Syntax&quot; :
 438      * <blockquote><pre>
 439      *          &lt;scheme&gt;://&lt;authority&gt;&lt;path&gt;?&lt;query&gt;#&lt;fragment&gt;
 440      * </pre></blockquote>
 441      * The reference is parsed into the scheme, authority, path, query and
 442      * fragment parts. If the path component is empty and the scheme,
 443      * authority, and query components are undefined, then the new URL is a
 444      * reference to the current document. Otherwise, the fragment and query
 445      * parts present in the spec are used in the new URL.
 446      * <p>
 447      * If the scheme component is defined in the given spec and does not match
 448      * the scheme of the context, then the new URL is created as an absolute
 449      * URL based on the spec alone. Otherwise the scheme component is inherited
 450      * from the context URL.
 451      * <p>
 452      * If the authority component is present in the spec then the spec is
 453      * treated as absolute and the spec authority and path will replace the
 454      * context authority and path. If the authority component is absent in the
 455      * spec then the authority of the new URL will be inherited from the
 456      * context.
 457      * <p>
 458      * If the spec's path component begins with a slash character
 459      * &quot;/&quot; then the
 460      * path is treated as absolute and the spec path replaces the context path.
 461      * <p>
 462      * Otherwise, the path is treated as a relative path and is appended to the
 463      * context path, as described in RFC2396. Also, in this case,
 464      * the path is canonicalized through the removal of directory
 465      * changes made by occurrences of &quot;..&quot; and &quot;.&quot;.
 466      * <p>
 467      * For a more detailed description of URL parsing, refer to RFC2396.
 468      *
 469      * @param      context   the context in which to parse the specification.
 470      * @param      spec      the {@code String} to parse as a URL.
 471      * @exception  MalformedURLException  if no protocol is specified, or an
 472      *               unknown protocol is found, or {@code spec} is {@code null}.
 473      * @see        java.net.URL#URL(java.lang.String, java.lang.String,
 474      *                  int, java.lang.String)
 475      * @see        java.net.URLStreamHandler
 476      * @see        java.net.URLStreamHandler#parseURL(java.net.URL,
 477      *                  java.lang.String, int, int)
 478      */
 479     public URL(URL context, String spec) throws MalformedURLException {
 480         this(context, spec, null);
 481     }
 482 
 483     /**
 484      * Creates a URL by parsing the given spec with the specified handler
 485      * within a specified context. If the handler is null, the parsing
 486      * occurs as with the two argument constructor.
 487      *
 488      * @param      context   the context in which to parse the specification.
 489      * @param      spec      the {@code String} to parse as a URL.
 490      * @param      handler   the stream handler for the URL.
 491      * @exception  MalformedURLException  if no protocol is specified, or an
 492      *               unknown protocol is found, or {@code spec} is {@code null}.
 493      * @exception  SecurityException
 494      *        if a security manager exists and its
 495      *        {@code checkPermission} method doesn't allow
 496      *        specifying a stream handler.
 497      * @see        java.net.URL#URL(java.lang.String, java.lang.String,
 498      *                  int, java.lang.String)
 499      * @see        java.net.URLStreamHandler
 500      * @see        java.net.URLStreamHandler#parseURL(java.net.URL,
 501      *                  java.lang.String, int, int)
 502      */
 503     public URL(URL context, String spec, URLStreamHandler handler)
 504         throws MalformedURLException
 505     {
 506         String original = spec;
 507         int i, limit, c;
 508         int start = 0;
 509         String newProtocol = null;
 510         boolean aRef=false;
 511         boolean isRelative = false;
 512 
 513         // Check for permission to specify a handler
 514         if (handler != null) {
 515             SecurityManager sm = System.getSecurityManager();
 516             if (sm != null) {
 517                 checkSpecifyHandler(sm);
 518             }
 519         }
 520 
 521         try {
 522             limit = spec.length();
 523             while ((limit > 0) && (spec.charAt(limit - 1) <= ' ')) {
 524                 limit--;        //eliminate trailing whitespace
 525             }
 526             while ((start < limit) && (spec.charAt(start) <= ' ')) {
 527                 start++;        // eliminate leading whitespace
 528             }
 529 
 530             if (spec.regionMatches(true, start, "url:", 0, 4)) {
 531                 start += 4;
 532             }
 533             if (start < spec.length() && spec.charAt(start) == '#') {
 534                 /* we're assuming this is a ref relative to the context URL.
 535                  * This means protocols cannot start w/ '#', but we must parse
 536                  * ref URL's like: "hello:there" w/ a ':' in them.
 537                  */
 538                 aRef=true;
 539             }
 540             for (i = start ; !aRef && (i < limit) &&
 541                      ((c = spec.charAt(i)) != '/') ; i++) {
 542                 if (c == ':') {
 543 
 544                     String s = spec.substring(start, i).toLowerCase();
 545                     if (isValidProtocol(s)) {
 546                         newProtocol = s;
 547                         start = i + 1;
 548                     }
 549                     break;
 550                 }
 551             }
 552 
 553             // Only use our context if the protocols match.
 554             protocol = newProtocol;
 555             if ((context != null) && ((newProtocol == null) ||
 556                             newProtocol.equalsIgnoreCase(context.protocol))) {
 557                 // inherit the protocol handler from the context
 558                 // if not specified to the constructor
 559                 if (handler == null) {
 560                     handler = context.handler;
 561                 }
 562 
 563                 // If the context is a hierarchical URL scheme and the spec
 564                 // contains a matching scheme then maintain backwards
 565                 // compatibility and treat it as if the spec didn't contain
 566                 // the scheme; see 5.2.3 of RFC2396
 567                 if (context.path != null && context.path.startsWith("/"))
 568                     newProtocol = null;
 569 
 570                 if (newProtocol == null) {
 571                     protocol = context.protocol;
 572                     authority = context.authority;
 573                     userInfo = context.userInfo;
 574                     host = context.host;
 575                     port = context.port;
 576                     file = context.file;
 577                     path = context.path;
 578                     isRelative = true;
 579                 }
 580             }
 581 
 582             if (protocol == null) {
 583                 throw new MalformedURLException("no protocol: "+original);
 584             }
 585 
 586             // Get the protocol handler if not specified or the protocol
 587             // of the context could not be used
 588             if (handler == null &&
 589                 (handler = getURLStreamHandler(protocol)) == null) {
 590                 throw new MalformedURLException("unknown protocol: "+protocol);
 591             }
 592 
 593             this.handler = handler;
 594 
 595             i = spec.indexOf('#', start);
 596             if (i >= 0) {
 597                 ref = spec.substring(i + 1, limit);
 598                 limit = i;
 599             }
 600 
 601             /*
 602              * Handle special case inheritance of query and fragment
 603              * implied by RFC2396 section 5.2.2.
 604              */
 605             if (isRelative && start == limit) {
 606                 query = context.query;
 607                 if (ref == null) {
 608                     ref = context.ref;
 609                 }
 610             }
 611 
 612             handler.parseURL(this, spec, start, limit);
 613 
 614         } catch(MalformedURLException e) {
 615             throw e;
 616         } catch(Exception e) {
 617             MalformedURLException exception = new MalformedURLException(e.getMessage());
 618             exception.initCause(e);
 619             throw exception;
 620         }
 621     }
 622 
 623     /*
 624      * Returns true if specified string is a valid protocol name.
 625      */
 626     private boolean isValidProtocol(String protocol) {
 627         int len = protocol.length();
 628         if (len < 1)
 629             return false;
 630         char c = protocol.charAt(0);
 631         if (!Character.isLetter(c))
 632             return false;
 633         for (int i = 1; i < len; i++) {
 634             c = protocol.charAt(i);
 635             if (!Character.isLetterOrDigit(c) && c != '.' && c != '+' &&
 636                 c != '-') {
 637                 return false;
 638             }
 639         }
 640         return true;
 641     }
 642 
 643     /*
 644      * Checks for permission to specify a stream handler.
 645      */
 646     private void checkSpecifyHandler(SecurityManager sm) {
 647         sm.checkPermission(SecurityConstants.SPECIFY_HANDLER_PERMISSION);
 648     }
 649 
 650     /**
 651      * Sets the fields of the URL. This is not a public method so that
 652      * only URLStreamHandlers can modify URL fields. URLs are
 653      * otherwise constant.
 654      *
 655      * @param protocol the name of the protocol to use
 656      * @param host the name of the host
 657        @param port the port number on the host
 658      * @param file the file on the host
 659      * @param ref the internal reference in the URL
 660      */
 661     void set(String protocol, String host, int port,
 662              String file, String ref) {
 663         synchronized (this) {
 664             this.protocol = protocol;
 665             this.host = host;
 666             authority = port == -1 ? host : host + ":" + port;
 667             this.port = port;
 668             this.file = file;
 669             this.ref = ref;
 670             /* This is very important. We must recompute this after the
 671              * URL has been changed. */
 672             hashCode = -1;
 673             hostAddress = null;
 674             int q = file.lastIndexOf('?');
 675             if (q != -1) {
 676                 query = file.substring(q+1);
 677                 path = file.substring(0, q);
 678             } else
 679                 path = file;
 680         }
 681     }
 682 
 683     /**
 684      * Sets the specified 8 fields of the URL. This is not a public method so
 685      * that only URLStreamHandlers can modify URL fields. URLs are otherwise
 686      * constant.
 687      *
 688      * @param protocol the name of the protocol to use
 689      * @param host the name of the host
 690      * @param port the port number on the host
 691      * @param authority the authority part for the url
 692      * @param userInfo the username and password
 693      * @param path the file on the host
 694      * @param ref the internal reference in the URL
 695      * @param query the query part of this URL
 696      * @since 1.3
 697      */
 698     void set(String protocol, String host, int port,
 699              String authority, String userInfo, String path,
 700              String query, String ref) {
 701         synchronized (this) {
 702             this.protocol = protocol;
 703             this.host = host;
 704             this.port = port;
 705             this.file = query == null ? path : path + "?" + query;
 706             this.userInfo = userInfo;
 707             this.path = path;
 708             this.ref = ref;
 709             /* This is very important. We must recompute this after the
 710              * URL has been changed. */
 711             hashCode = -1;
 712             hostAddress = null;
 713             this.query = query;
 714             this.authority = authority;
 715         }
 716     }
 717 
 718     /**
 719      * Gets the query part of this {@code URL}.
 720      *
 721      * @return  the query part of this {@code URL},
 722      * or <CODE>null</CODE> if one does not exist
 723      * @since 1.3
 724      */
 725     public String getQuery() {
 726         return query;
 727     }
 728 
 729     /**
 730      * Gets the path part of this {@code URL}.
 731      *
 732      * @return  the path part of this {@code URL}, or an
 733      * empty string if one does not exist
 734      * @since 1.3
 735      */
 736     public String getPath() {
 737         return path;
 738     }
 739 
 740     /**
 741      * Gets the userInfo part of this {@code URL}.
 742      *
 743      * @return  the userInfo part of this {@code URL}, or
 744      * <CODE>null</CODE> if one does not exist
 745      * @since 1.3
 746      */
 747     public String getUserInfo() {
 748         return userInfo;
 749     }
 750 
 751     /**
 752      * Gets the authority part of this {@code URL}.
 753      *
 754      * @return  the authority part of this {@code URL}
 755      * @since 1.3
 756      */
 757     public String getAuthority() {
 758         return authority;
 759     }
 760 
 761     /**
 762      * Gets the port number of this {@code URL}.
 763      *
 764      * @return  the port number, or -1 if the port is not set
 765      */
 766     public int getPort() {
 767         return port;
 768     }
 769 
 770     /**
 771      * Gets the default port number of the protocol associated
 772      * with this {@code URL}. If the URL scheme or the URLStreamHandler
 773      * for the URL do not define a default port number,
 774      * then -1 is returned.
 775      *
 776      * @return  the port number
 777      * @since 1.4
 778      */
 779     public int getDefaultPort() {
 780         return handler.getDefaultPort();
 781     }
 782 
 783     /**
 784      * Gets the protocol name of this {@code URL}.
 785      *
 786      * @return  the protocol of this {@code URL}.
 787      */
 788     public String getProtocol() {
 789         return protocol;
 790     }
 791 
 792     /**
 793      * Gets the host name of this {@code URL}, if applicable.
 794      * The format of the host conforms to RFC 2732, i.e. for a
 795      * literal IPv6 address, this method will return the IPv6 address
 796      * enclosed in square brackets ({@code '['} and {@code ']'}).
 797      *
 798      * @return  the host name of this {@code URL}.
 799      */
 800     public String getHost() {
 801         return host;
 802     }
 803 
 804     /**
 805      * Gets the file name of this {@code URL}.
 806      * The returned file portion will be
 807      * the same as <CODE>getPath()</CODE>, plus the concatenation of
 808      * the value of <CODE>getQuery()</CODE>, if any. If there is
 809      * no query portion, this method and <CODE>getPath()</CODE> will
 810      * return identical results.
 811      *
 812      * @return  the file name of this {@code URL},
 813      * or an empty string if one does not exist
 814      */
 815     public String getFile() {
 816         return file;
 817     }
 818 
 819     /**
 820      * Gets the anchor (also known as the "reference") of this
 821      * {@code URL}.
 822      *
 823      * @return  the anchor (also known as the "reference") of this
 824      *          {@code URL}, or <CODE>null</CODE> if one does not exist
 825      */
 826     public String getRef() {
 827         return ref;
 828     }
 829 
 830     /**
 831      * Compares this URL for equality with another object.<p>
 832      *
 833      * If the given object is not a URL then this method immediately returns
 834      * {@code false}.<p>
 835      *
 836      * Two URL objects are equal if they have the same protocol, reference
 837      * equivalent hosts, have the same port number on the host, and the same
 838      * file and fragment of the file.<p>
 839      *
 840      * Two hosts are considered equivalent if both host names can be resolved
 841      * into the same IP addresses; else if either host name can't be
 842      * resolved, the host names must be equal without regard to case; or both
 843      * host names equal to null.<p>
 844      *
 845      * Since hosts comparison requires name resolution, this operation is a
 846      * blocking operation. <p>
 847      *
 848      * Note: The defined behavior for {@code equals} is known to
 849      * be inconsistent with virtual hosting in HTTP.
 850      *
 851      * @param   obj   the URL to compare against.
 852      * @return  {@code true} if the objects are the same;
 853      *          {@code false} otherwise.
 854      */
 855     public boolean equals(Object obj) {
 856         if (!(obj instanceof URL))
 857             return false;
 858         URL u2 = (URL)obj;
 859 
 860         return handler.equals(this, u2);
 861     }
 862 
 863     /**
 864      * Creates an integer suitable for hash table indexing.<p>
 865      *
 866      * The hash code is based upon all the URL components relevant for URL
 867      * comparison. As such, this operation is a blocking operation.
 868      *
 869      * @return  a hash code for this {@code URL}.
 870      */
 871     public synchronized int hashCode() {
 872         if (hashCode != -1)
 873             return hashCode;
 874 
 875         hashCode = handler.hashCode(this);
 876         return hashCode;
 877     }
 878 
 879     /**
 880      * Compares two URLs, excluding the fragment component.<p>
 881      *
 882      * Returns {@code true} if this {@code URL} and the
 883      * {@code other} argument are equal without taking the
 884      * fragment component into consideration.
 885      *
 886      * @param   other   the {@code URL} to compare against.
 887      * @return  {@code true} if they reference the same remote object;
 888      *          {@code false} otherwise.
 889      */
 890     public boolean sameFile(URL other) {
 891         return handler.sameFile(this, other);
 892     }
 893 
 894     /**
 895      * Constructs a string representation of this {@code URL}. The
 896      * string is created by calling the {@code toExternalForm}
 897      * method of the stream protocol handler for this object.
 898      *
 899      * @return  a string representation of this object.
 900      * @see     java.net.URL#URL(java.lang.String, java.lang.String, int,
 901      *                  java.lang.String)
 902      * @see     java.net.URLStreamHandler#toExternalForm(java.net.URL)
 903      */
 904     public String toString() {
 905         return toExternalForm();
 906     }
 907 
 908     /**
 909      * Constructs a string representation of this {@code URL}. The
 910      * string is created by calling the {@code toExternalForm}
 911      * method of the stream protocol handler for this object.
 912      *
 913      * @return  a string representation of this object.
 914      * @see     java.net.URL#URL(java.lang.String, java.lang.String,
 915      *                  int, java.lang.String)
 916      * @see     java.net.URLStreamHandler#toExternalForm(java.net.URL)
 917      */
 918     public String toExternalForm() {
 919         return handler.toExternalForm(this);
 920     }
 921 
 922     /**
 923      * Returns a {@link java.net.URI} equivalent to this URL.
 924      * This method functions in the same way as {@code new URI (this.toString())}.
 925      * <p>Note, any URL instance that complies with RFC 2396 can be converted
 926      * to a URI. However, some URLs that are not strictly in compliance
 927      * can not be converted to a URI.
 928      *
 929      * @exception URISyntaxException if this URL is not formatted strictly according to
 930      *            to RFC2396 and cannot be converted to a URI.
 931      *
 932      * @return    a URI instance equivalent to this URL.
 933      * @since 1.5
 934      */
 935     public URI toURI() throws URISyntaxException {
 936         return new URI (toString());
 937     }
 938 
 939     /**
 940      * Returns a {@link java.net.URLConnection URLConnection} instance that
 941      * represents a connection to the remote object referred to by the
 942      * {@code URL}.
 943      *
 944      * <P>A new instance of {@linkplain java.net.URLConnection URLConnection} is
 945      * created every time when invoking the
 946      * {@linkplain java.net.URLStreamHandler#openConnection(URL)
 947      * URLStreamHandler.openConnection(URL)} method of the protocol handler for
 948      * this URL.</P>
 949      *
 950      * <P>It should be noted that a URLConnection instance does not establish
 951      * the actual network connection on creation. This will happen only when
 952      * calling {@linkplain java.net.URLConnection#connect() URLConnection.connect()}.</P>
 953      *
 954      * <P>If for the URL's protocol (such as HTTP or JAR), there
 955      * exists a public, specialized URLConnection subclass belonging
 956      * to one of the following packages or one of their subpackages:
 957      * java.lang, java.io, java.util, java.net, the connection
 958      * returned will be of that subclass. For example, for HTTP an
 959      * HttpURLConnection will be returned, and for JAR a
 960      * JarURLConnection will be returned.</P>
 961      *
 962      * @return     a {@link java.net.URLConnection URLConnection} linking
 963      *             to the URL.
 964      * @exception  IOException  if an I/O exception occurs.
 965      * @see        java.net.URL#URL(java.lang.String, java.lang.String,
 966      *             int, java.lang.String)
 967      */
 968     public URLConnection openConnection() throws java.io.IOException {
 969         return handler.openConnection(this);
 970     }
 971 
 972     /**
 973      * Same as {@link #openConnection()}, except that the connection will be
 974      * made through the specified proxy; Protocol handlers that do not
 975      * support proxing will ignore the proxy parameter and make a
 976      * normal connection.
 977      *
 978      * Invoking this method preempts the system's default
 979      * {@link java.net.ProxySelector ProxySelector} settings.
 980      *
 981      * @param      proxy the Proxy through which this connection
 982      *             will be made. If direct connection is desired,
 983      *             Proxy.NO_PROXY should be specified.
 984      * @return     a {@code URLConnection} to the URL.
 985      * @exception  IOException  if an I/O exception occurs.
 986      * @exception  SecurityException if a security manager is present
 987      *             and the caller doesn't have permission to connect
 988      *             to the proxy.
 989      * @exception  IllegalArgumentException will be thrown if proxy is null,
 990      *             or proxy has the wrong type
 991      * @exception  UnsupportedOperationException if the subclass that
 992      *             implements the protocol handler doesn't support
 993      *             this method.
 994      * @see        java.net.URL#URL(java.lang.String, java.lang.String,
 995      *             int, java.lang.String)
 996      * @see        java.net.URLConnection
 997      * @see        java.net.URLStreamHandler#openConnection(java.net.URL,
 998      *             java.net.Proxy)
 999      * @since      1.5
1000      */
1001     public URLConnection openConnection(Proxy proxy)
1002         throws java.io.IOException {
1003         if (proxy == null) {
1004             throw new IllegalArgumentException("proxy can not be null");
1005         }
1006 
1007         // Create a copy of Proxy as a security measure
1008         Proxy p = proxy == Proxy.NO_PROXY ? Proxy.NO_PROXY : sun.net.ApplicationProxy.create(proxy);
1009         SecurityManager sm = System.getSecurityManager();
1010         if (p.type() != Proxy.Type.DIRECT && sm != null) {
1011             InetSocketAddress epoint = (InetSocketAddress) p.address();
1012             if (epoint.isUnresolved())
1013                 sm.checkConnect(epoint.getHostName(), epoint.getPort());
1014             else
1015                 sm.checkConnect(epoint.getAddress().getHostAddress(),
1016                                 epoint.getPort());
1017         }
1018         return handler.openConnection(this, p);
1019     }
1020 
1021     /**
1022      * Opens a connection to this {@code URL} and returns an
1023      * {@code InputStream} for reading from that connection. This
1024      * method is a shorthand for:
1025      * <blockquote><pre>
1026      *     openConnection().getInputStream()
1027      * </pre></blockquote>
1028      *
1029      * @return     an input stream for reading from the URL connection.
1030      * @exception  IOException  if an I/O exception occurs.
1031      * @see        java.net.URL#openConnection()
1032      * @see        java.net.URLConnection#getInputStream()
1033      */
1034     public final InputStream openStream() throws java.io.IOException {
1035         return openConnection().getInputStream();
1036     }
1037 
1038     /**
1039      * Gets the contents of this URL. This method is a shorthand for:
1040      * <blockquote><pre>
1041      *     openConnection().getContent()
1042      * </pre></blockquote>
1043      *
1044      * @return     the contents of this URL.
1045      * @exception  IOException  if an I/O exception occurs.
1046      * @see        java.net.URLConnection#getContent()
1047      */
1048     public final Object getContent() throws java.io.IOException {
1049         return openConnection().getContent();
1050     }
1051 
1052     /**
1053      * Gets the contents of this URL. This method is a shorthand for:
1054      * <blockquote><pre>
1055      *     openConnection().getContent(classes)
1056      * </pre></blockquote>
1057      *
1058      * @param classes an array of Java types
1059      * @return     the content object of this URL that is the first match of
1060      *               the types specified in the classes array.
1061      *               null if none of the requested types are supported.
1062      * @exception  IOException  if an I/O exception occurs.
1063      * @see        java.net.URLConnection#getContent(Class[])
1064      * @since 1.3
1065      */
1066     public final Object getContent(Class<?>[] classes)
1067     throws java.io.IOException {
1068         return openConnection().getContent(classes);
1069     }
1070 
1071     /**
1072      * The URLStreamHandler factory.
1073      */
1074     static URLStreamHandlerFactory factory;
1075 
1076     /**
1077      * Sets an application's {@code URLStreamHandlerFactory}.
1078      * This method can be called at most once in a given Java Virtual
1079      * Machine.
1080      *
1081      *<p> The {@code URLStreamHandlerFactory} instance is used to
1082      *construct a stream protocol handler from a protocol name.
1083      *
1084      * <p> If there is a security manager, this method first calls
1085      * the security manager's {@code checkSetFactory} method
1086      * to ensure the operation is allowed.
1087      * This could result in a SecurityException.
1088      *
1089      * @param      fac   the desired factory.
1090      * @exception  Error  if the application has already set a factory.
1091      * @exception  SecurityException  if a security manager exists and its
1092      *             {@code checkSetFactory} method doesn't allow
1093      *             the operation.
1094      * @see        java.net.URL#URL(java.lang.String, java.lang.String,
1095      *             int, java.lang.String)
1096      * @see        java.net.URLStreamHandlerFactory
1097      * @see        SecurityManager#checkSetFactory
1098      */
1099     public static void setURLStreamHandlerFactory(URLStreamHandlerFactory fac) {
1100         synchronized (streamHandlerLock) {
1101             if (factory != null) {
1102                 throw new Error("factory already defined");
1103             }
1104             SecurityManager security = System.getSecurityManager();
1105             if (security != null) {
1106                 security.checkSetFactory();
1107             }
1108             handlers.clear();
1109             factory = fac;
1110         }
1111     }
1112 
1113     /**
1114      * A table of protocol handlers.
1115      */
1116     static Hashtable<String,URLStreamHandler> handlers = new Hashtable<>();
1117     private static Object streamHandlerLock = new Object();
1118 
1119     /**
1120      * Returns the Stream Handler.
1121      * @param protocol the protocol to use
1122      */
1123     static URLStreamHandler getURLStreamHandler(String protocol) {
1124 
1125         URLStreamHandler handler = handlers.get(protocol);
1126         if (handler == null) {
1127 
1128             boolean checkedWithFactory = false;
1129 
1130             // Use the factory (if any)
1131             if (factory != null) {
1132                 handler = factory.createURLStreamHandler(protocol);
1133                 checkedWithFactory = true;
1134             }
1135 
1136             // Try java protocol handler
1137             if (handler == null) {
1138                 String packagePrefixList = null;
1139 
1140                 packagePrefixList
1141                     = java.security.AccessController.doPrivileged(
1142                     new sun.security.action.GetPropertyAction(
1143                         protocolPathProp,""));
1144                 if (packagePrefixList != "") {
1145                     packagePrefixList += "|";
1146                 }
1147 
1148                 // REMIND: decide whether to allow the "null" class prefix
1149                 // or not.
1150                 packagePrefixList += "sun.net.www.protocol";
1151 
1152                 StringTokenizer packagePrefixIter =
1153                     new StringTokenizer(packagePrefixList, "|");
1154 
1155                 while (handler == null &&
1156                        packagePrefixIter.hasMoreTokens()) {
1157 
1158                     String packagePrefix =
1159                       packagePrefixIter.nextToken().trim();
1160                     try {
1161                         String clsName = packagePrefix + "." + protocol +
1162                           ".Handler";
1163                         Class<?> cls = null;
1164                         try {
1165                             cls = Class.forName(clsName);
1166                         } catch (ClassNotFoundException e) {
1167                             ClassLoader cl = ClassLoader.getSystemClassLoader();
1168                             if (cl != null) {
1169                                 cls = cl.loadClass(clsName);
1170                             }
1171                         }
1172                         if (cls != null) {
1173                             handler  =
1174                               (URLStreamHandler)cls.newInstance();
1175                         }
1176                     } catch (Exception e) {
1177                         // any number of exceptions can get thrown here
1178                     }
1179                 }
1180             }
1181 
1182             synchronized (streamHandlerLock) {
1183 
1184                 URLStreamHandler handler2 = null;
1185 
1186                 // Check again with hashtable just in case another
1187                 // thread created a handler since we last checked
1188                 handler2 = handlers.get(protocol);
1189 
1190                 if (handler2 != null) {
1191                     return handler2;
1192                 }
1193 
1194                 // Check with factory if another thread set a
1195                 // factory since our last check
1196                 if (!checkedWithFactory && factory != null) {
1197                     handler2 = factory.createURLStreamHandler(protocol);
1198                 }
1199 
1200                 if (handler2 != null) {
1201                     // The handler from the factory must be given more
1202                     // importance. Discard the default handler that
1203                     // this thread created.
1204                     handler = handler2;
1205                 }
1206 
1207                 // Insert this handler into the hashtable
1208                 if (handler != null) {
1209                     handlers.put(protocol, handler);
1210                 }
1211 
1212             }
1213         }
1214 
1215         return handler;
1216 
1217     }
1218 
1219     /**
1220      * WriteObject is called to save the state of the URL to an
1221      * ObjectOutputStream. The handler is not saved since it is
1222      * specific to this system.
1223      *
1224      * @serialData the default write object value. When read back in,
1225      * the reader must ensure that calling getURLStreamHandler with
1226      * the protocol variable returns a valid URLStreamHandler and
1227      * throw an IOException if it does not.
1228      */
1229     private synchronized void writeObject(java.io.ObjectOutputStream s)
1230         throws IOException
1231     {
1232         s.defaultWriteObject(); // write the fields
1233     }
1234 
1235     /**
1236      * readObject is called to restore the state of the URL from the
1237      * stream.  It reads the components of the URL and finds the local
1238      * stream handler.
1239      */
1240     private synchronized void readObject(java.io.ObjectInputStream s)
1241          throws IOException, ClassNotFoundException
1242     {
1243         s.defaultReadObject();  // read the fields
1244         if ((handler = getURLStreamHandler(protocol)) == null) {
1245             throw new IOException("unknown protocol: " + protocol);
1246         }
1247 
1248         // Construct authority part
1249         if (authority == null &&
1250             ((host != null && host.length() > 0) || port != -1)) {
1251             if (host == null)
1252                 host = "";
1253             authority = (port == -1) ? host : host + ":" + port;
1254 
1255             // Handle hosts with userInfo in them
1256             int at = host.lastIndexOf('@');
1257             if (at != -1) {
1258                 userInfo = host.substring(0, at);
1259                 host = host.substring(at+1);
1260             }
1261         } else if (authority != null) {
1262             // Construct user info part
1263             int ind = authority.indexOf('@');
1264             if (ind != -1)
1265                 userInfo = authority.substring(0, ind);
1266         }
1267 
1268         // Construct path and query part
1269         path = null;
1270         query = null;
1271         if (file != null) {
1272             // Fix: only do this if hierarchical?
1273             int q = file.lastIndexOf('?');
1274             if (q != -1) {
1275                 query = file.substring(q+1);
1276                 path = file.substring(0, q);
1277             } else
1278                 path = file;
1279         }
1280     }
1281 }
1282 
1283 class Parts {
1284     String path, query, ref;
1285 
1286     Parts(String file) {
1287         int ind = file.indexOf('#');
1288         ref = ind < 0 ? null: file.substring(ind + 1);
1289         file = ind < 0 ? file: file.substring(0, ind);
1290         int q = file.lastIndexOf('?');
1291         if (q != -1) {
1292             query = file.substring(q+1);
1293             path = file.substring(0, q);
1294         } else {
1295             path = file;
1296         }
1297     }
1298 
1299     String getPath() {
1300         return path;
1301     }
1302 
1303     String getQuery() {
1304         return query;
1305     }
1306 
1307     String getRef() {
1308         return ref;
1309     }
1310 }