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479 lines
16 KiB
Java
479 lines
16 KiB
Java
/* URLStreamHandler.java -- Abstract superclass for all protocol handlers
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Copyright (C) 1998, 1999, 2002, 2003 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.net;
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import java.io.IOException;
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import java.io.File;
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/*
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* Written using on-line Java Platform 1.2 API Specification, as well
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* as "The Java Class Libraries", 2nd edition (Addison-Wesley, 1998).
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* Status: Believed complete and correct.
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*/
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/**
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* This class is the superclass of all URL protocol handlers. The URL
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* class loads the appropriate protocol handler to establish a connection
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* to a (possibly) remote service (eg, "http", "ftp") and to do protocol
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* specific parsing of URL's. Refer to the URL class documentation for
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* details on how that class locates and loads protocol handlers.
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* <p>
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* A protocol handler implementation should override the openConnection()
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* method, and optionally override the parseURL() and toExternalForm()
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* methods if necessary. (The default implementations will parse/write all
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* URL's in the same form as http URL's). A protocol specific subclass
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* of URLConnection will most likely need to be created as well.
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* <p>
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* Note that the instance methods in this class are called as if they
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* were static methods. That is, a URL object to act on is passed with
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* every call rather than the caller assuming the URL is stored in an
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* instance variable of the "this" object.
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* <p>
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* The methods in this class are protected and accessible only to subclasses.
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* URLStreamConnection objects are intended for use by the URL class only,
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* not by other classes (unless those classes are implementing protocols).
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*
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* @author Aaron M. Renn (arenn@urbanophile.com)
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* @author Warren Levy (warrenl@cygnus.com)
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*
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* @see URL
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*/
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public abstract class URLStreamHandler
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{
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/**
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* Creates a URLStreamHander
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*/
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public URLStreamHandler ()
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{
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}
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/**
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* Returns a URLConnection for the passed in URL. Note that this should
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* not actually create the connection to the (possibly) remote host, but
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* rather simply return a URLConnection object. The connect() method of
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* URL connection is used to establish the actual connection, possibly
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* after the caller sets up various connection options.
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*
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* @param url The URL to get a connection object for
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*
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* @return A URLConnection object for the given URL
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*
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* @exception IOException If an error occurs
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*/
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protected abstract URLConnection openConnection(URL u)
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throws IOException;
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/**
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* This method parses the string passed in as a URL and set's the
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* instance data fields in the URL object passed in to the various values
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* parsed out of the string. The start parameter is the position to start
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* scanning the string. This is usually the position after the ":" which
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* terminates the protocol name. The end parameter is the position to
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* stop scanning. This will be either the end of the String, or the
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* position of the "#" character, which separates the "file" portion of
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* the URL from the "anchor" portion.
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* <p>
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* This method assumes URL's are formatted like http protocol URL's, so
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* subclasses that implement protocols with URL's the follow a different
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* syntax should override this method. The lone exception is that if
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* the protocol name set in the URL is "file", this method will accept
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* an empty hostname (i.e., "file:///"), which is legal for that protocol
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*
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* @param url The URL object in which to store the results
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* @param spec The String-ized URL to parse
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* @param start The position in the string to start scanning from
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* @param end The position in the string to stop scanning
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*/
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protected void parseURL(URL url, String spec, int start, int end)
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{
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String host = url.getHost();
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int port = url.getPort();
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String file = url.getFile();
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String ref = url.getRef();
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if (spec.regionMatches (start, "//", 0, 2))
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{
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int hostEnd;
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int colon;
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start += 2;
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int slash = spec.indexOf('/', start);
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if (slash >= 0)
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hostEnd = slash;
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else
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hostEnd = end;
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host = spec.substring (start, hostEnd);
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// Look for optional port number. It is valid for the non-port
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// part of the host name to be null (e.g. a URL "http://:80").
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// TBD: JDK 1.2 in this case sets host to null rather than "";
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// this is undocumented and likely an unintended side effect in 1.2
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// so we'll be simple here and stick with "". Note that
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// "http://" or "http:///" produce a "" host in JDK 1.2.
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if ((colon = host.indexOf(':')) >= 0)
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{
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try
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{
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port = Integer.parseInt(host.substring(colon + 1));
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}
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catch (NumberFormatException e)
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{
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; // Ignore invalid port values; port is already set to u's
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// port.
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}
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host = host.substring(0, colon);
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}
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file = null;
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start = hostEnd;
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}
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else if (host == null)
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host = "";
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if (file == null || file.length() == 0
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|| (start < end && spec.charAt(start) == '/'))
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{
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// No file context available; just spec for file.
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// Or this is an absolute path name; ignore any file context.
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file = spec.substring(start, end);
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ref = null;
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}
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else if (start < end)
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{
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// Context is available, but only override it if there is a new file.
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char sepChar = '/';
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int lastSlash = file.lastIndexOf (sepChar);
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if (lastSlash < 0 && File.separatorChar != sepChar
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&& url.getProtocol ().equals ("file"))
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{
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// On Windows, even '\' is allowed in a "file" URL.
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sepChar = File.separatorChar;
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lastSlash = file.lastIndexOf (sepChar);
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}
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file = file.substring(0, lastSlash)
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+ sepChar + spec.substring (start, end);
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if (url.getProtocol ().equals ("file"))
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{
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// For "file" URLs constructed relative to a context, we
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// need to canonicalise the file path.
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try
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{
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file = new File (file).getCanonicalPath ();
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}
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catch (IOException e)
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{
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}
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}
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ref = null;
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}
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if (ref == null)
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{
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// Normally there should be no '#' in the file part,
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// but we are nice.
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int hash = file.indexOf('#');
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if (hash != -1)
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{
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ref = file.substring(hash + 1, file.length());
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file = file.substring(0, hash);
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}
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}
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// XXX - Classpath used to call PlatformHelper.toCanonicalForm() on
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// the file part. It seems like overhead, but supposedly there is some
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// benefit in windows based systems (it also lowercased the string).
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setURL(url, url.getProtocol(), host, port, file, ref);
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}
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private static String canonicalizeFilename(String file)
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{
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// XXX - GNU Classpath has an implementation that might be more appropriate
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// for Windows based systems (gnu.java.io.PlatformHelper.toCanonicalForm)
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int index;
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// Replace "/./" with "/". This probably isn't very efficient in
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// the general case, but it's probably not bad most of the time.
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while ((index = file.indexOf("/./")) >= 0)
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file = file.substring(0, index) + file.substring(index + 2);
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// Process "/../" correctly. This probably isn't very efficient in
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// the general case, but it's probably not bad most of the time.
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while ((index = file.indexOf("/../")) >= 0)
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{
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// Strip of the previous directory - if it exists.
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int previous = file.lastIndexOf('/', index - 1);
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if (previous >= 0)
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file = file.substring(0, previous) + file.substring(index + 3);
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else
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break;
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}
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return file;
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}
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/**
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* Compares two URLs, excluding the fragment component
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*
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* @param url1 The first url
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* @param url2 The second url to compare with the first
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*
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* @specnote Now protected
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*/
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protected boolean sameFile(URL url1, URL url2)
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{
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if (url1 == url2)
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return true;
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// This comparison is very conservative. It assumes that any
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// field can be null.
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if (url1 == null || url2 == null || url1.getPort() != url2.getPort())
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return false;
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String s1, s2;
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s1 = url1.getProtocol();
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s2 = url2.getProtocol();
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if (s1 != s2 && (s1 == null || ! s1.equals(s2)))
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return false;
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s1 = url1.getHost();
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s2 = url2.getHost();
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if (s1 != s2 && (s1 == null || ! s1.equals(s2)))
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return false;
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s1 = canonicalizeFilename(url1.getFile());
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s2 = canonicalizeFilename(url2.getFile());
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if (s1 != s2 && (s1 == null || ! s1.equals(s2)))
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return false;
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return true;
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}
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/**
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* This methods sets the instance variables representing the various fields
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* of the URL to the values passed in.
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*
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* @param u The URL to modify
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* @param protocol The protocol to set
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* @param host The host name to et
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* @param port The port number to set
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* @param file The filename to set
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* @param ref The reference
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*
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* @exception SecurityException If the protocol handler of the URL is
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* different from this one
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*
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* @deprecated 1.2 Please use
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* #setURL(URL,String,String,int,String,String,String,String);
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*/
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protected void setURL(URL u, String protocol, String host, int port,
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String file, String ref)
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{
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u.set(protocol, host, port, file, ref);
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}
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/**
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* Sets the fields of the URL argument to the indicated values
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*
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* @param u The URL to modify
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* @param protocol The protocol to set
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* @param host The host name to set
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* @param port The port number to set
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* @param authority The authority to set
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* @param userInfo The user information to set
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* @param path The path/filename to set
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* @param query The query part to set
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* @param ref The reference
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*
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* @exception SecurityException If the protocol handler of the URL is
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* different from this one
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*/
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protected void setURL(URL u, String protocol, String host, int port,
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String authority, String userInfo, String path,
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String query, String ref)
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{
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u.set(protocol, host, port, authority, userInfo, path, query, ref);
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}
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/**
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* Provides the default equals calculation. May be overidden by handlers for
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* other protocols that have different requirements for equals(). This method
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* requires that none of its arguments is null. This is guaranteed by the
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* fact that it is only called by java.net.URL class.
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*
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* @param url1 An URL object
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* @param url2 An URL object
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*/
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protected boolean equals (URL url1, URL url2)
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{
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// This comparison is very conservative. It assumes that any
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// field can be null.
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return (url1.getPort () == url2.getPort ()
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&& ((url1.getProtocol () == null && url2.getProtocol () == null)
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|| (url1.getProtocol () != null
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&& url1.getProtocol ().equals (url2.getProtocol ())))
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&& ((url1.getUserInfo () == null && url2.getUserInfo () == null)
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|| (url1.getUserInfo () != null
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&& url1.getUserInfo ().equals(url2.getUserInfo ())))
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&& ((url1.getAuthority () == null && url2.getAuthority () == null)
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|| (url1.getAuthority () != null
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&& url1.getAuthority ().equals(url2.getAuthority ())))
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&& ((url1.getHost () == null && url2.getHost () == null)
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|| (url1.getHost () != null
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&& url1.getHost ().equals(url2.getHost ())))
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&& ((url1.getPath () == null && url2.getPath () == null)
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|| (url1.getPath () != null
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&& url1.getPath ().equals (url2.getPath ())))
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&& ((url1.getQuery () == null && url2.getQuery () == null)
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|| (url1.getQuery () != null
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&& url1.getQuery ().equals(url2.getQuery ())))
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&& ((url1.getRef () == null && url2.getRef () == null)
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|| (url1.getRef () != null
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&& url1.getRef ().equals(url2.getRef ()))));
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}
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/**
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* Compares the host components of two URLs.
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*
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* @exception UnknownHostException If an unknown host is found
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*/
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protected boolean hostsEqual (URL url1, URL url2)
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throws UnknownHostException
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{
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InetAddress addr1 = InetAddress.getByName (url1.getHost ());
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InetAddress addr2 = InetAddress.getByName (url2.getHost ());
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return addr1.equals (addr2);
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}
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/**
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* Get the IP address of our host. An empty host field or a DNS failure will
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* result in a null return.
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*/
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protected InetAddress getHostAddress (URL url)
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{
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String hostname = url.getHost ();
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if (hostname == "")
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return null;
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try
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{
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return InetAddress.getByName (hostname);
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}
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catch (UnknownHostException e)
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{
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return null;
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}
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}
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/**
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* Returns the default port for a URL parsed by this handler. This method is
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* meant to be overidden by handlers with default port numbers.
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*/
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protected int getDefaultPort ()
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{
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return -1;
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}
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/**
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* Provides the default hash calculation. May be overidden by handlers for
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* other protocols that have different requirements for hashCode calculation.
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*/
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protected int hashCode (URL url)
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{
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return url.getProtocol ().hashCode () +
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((url.getHost () == null) ? 0 : url.getHost ().hashCode ()) +
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url.getFile ().hashCode() +
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url.getPort ();
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}
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/**
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* This method converts a URL object into a String. This method creates
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* Strings in the mold of http URL's, so protocol handlers which use URL's
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* that have a different syntax should override this method
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*
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* @param url The URL object to convert
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*/
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protected String toExternalForm(URL u)
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{
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String protocol, host, file, ref;
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int port;
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protocol = u.getProtocol();
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// JDK 1.2 online doc infers that host could be null because it
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// explicitly states that file cannot be null, but is silent on host.
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host = u.getHost();
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if (host == null)
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host = "";
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port = u.getPort();
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file = u.getFile();
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ref = u.getRef();
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// Guess a reasonable size for the string buffer so we have to resize
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// at most once.
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int size = protocol.length() + host.length() + file.length() + 24;
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StringBuffer sb = new StringBuffer(size);
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if (protocol != null && protocol.length() > 0)
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{
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sb.append(protocol);
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sb.append(":");
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}
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if (host.length() != 0)
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sb.append("//").append(host);
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// Note that this produces different results from JDK 1.2 as JDK 1.2
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// ignores a non-default port if host is null or "". That is inconsistent
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// with the spec since the result of this method is spec'ed so it can be
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// used to construct a new URL that is equivalent to the original.
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boolean port_needed = port > 0 && port != getDefaultPort();
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if (port_needed)
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sb.append(':').append(port);
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sb.append(file);
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if (ref != null)
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sb.append('#').append(ref);
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return sb.toString();
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}
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}
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