264 lines
8.9 KiB
Java
264 lines
8.9 KiB
Java
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/* Resolver.java --
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Copyright (C) 1999,2000,2001 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., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 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 gnu.xml.util;
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import java.io.File;
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import java.io.IOException;
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import java.util.Dictionary;
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import org.xml.sax.EntityResolver;
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import org.xml.sax.InputSource;
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import org.xml.sax.SAXException;
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/**
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* Utility implementation of a SAX resolver, which can be used to improve
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* network utilization of SAX based XML components. It does this by
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* supporting local caches of external entities.
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* SAX parsers <em>should</em> use such local caches when possible.
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*
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* @see XCat
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*/
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public class Resolver implements EntityResolver, Cloneable
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{
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/**
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* Updates a dictionary used to map PUBLIC identifiers to file names,
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* so that it uses the mappings in a specified directory.
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*
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* @param mappings Array of string pairs, where the first member
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* of each pair is a PUBLIC identifier and the second is the
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* name of a file, relative to the specified directory.
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* @param directory File holding the specified files.
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*/
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public static void addDirectoryMapping (
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Dictionary table,
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String mappings [][],
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File directory
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) throws IOException
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{
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for (int i = 0; i < mappings.length; i++) {
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File file = new File (directory, mappings [i][1]);
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String temp;
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if (!file.exists ()) // ?? log a warning ??
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continue;
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temp = fileToURL (file);
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table.put (mappings [i][0], temp);
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}
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}
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// FIXME: these *URL routines don't quite belong here, except
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// that they're all in the same spirit of making it easy to
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// use local filesystem URIs with XML parsers.
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/**
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* Provides the URL for a named file, without relying on the JDK 1.2
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* {@link java.io.File#toURL File.toURL}() utility method.
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*
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* @param filename the file name to convert. Relative file names
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* are resolved the way the JVM resolves them (current to the
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* process-global current working directory).
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*
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* @exception IOException if the file does not exist
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*/
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public static String fileNameToURL (String filename)
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throws IOException
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{
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return fileToURL (new File (filename));
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}
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/**
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* Provides the URL for a file, without relying on the JDK 1.2
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* {@link java.io.File#toURL File.toURL}() utility method.
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*
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* @param f the file to convert. Relative file names
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* are resolved the way the JVM resolves them (current to the
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* process-global current working directory).
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*
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* @exception IOException if the file does not exist
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*/
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public static String fileToURL (File f)
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throws IOException
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{
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String temp;
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// NOTE: the javax.xml.parsers.DocumentBuilder and
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// javax.xml.transform.stream.StreamSource versions
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// of this don't have this test. Some JVM versions
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// don't report this error sanely through URL code.
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if (!f.exists ())
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throw new IOException ("no such file: " + f.getName ());
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// FIXME: getAbsolutePath() seems buggy; I'm seeing components
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// like "/foo/../" which are clearly not "absolute"
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// and should have been resolved with the filesystem.
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// Substituting "/" would be wrong, "foo" may have been
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// symlinked ... the URL code will make that change
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// later, so that things can get _really_ broken!
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temp = f.getAbsolutePath ();
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if (File.separatorChar != '/')
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temp = temp.replace (File.separatorChar, '/');
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if (!temp.startsWith ("/"))
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temp = "/" + temp;
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if (!temp.endsWith ("/") && f.isDirectory ())
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temp = temp + "/";
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return "file:" + temp;
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}
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/**
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* Returns a URL string. Note that if a malformed URL is provided, or
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* the parameter names a nonexistent file, the resulting URL may be
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* malformed.
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*
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* @param fileOrURL If this is the name of a file which exists,
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* then its URL is returned. Otherwise the argument is returned.
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*/
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public static String getURL (String fileOrURL)
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{
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try {
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return fileNameToURL (fileOrURL);
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} catch (Exception e) {
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return fileOrURL;
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}
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}
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// note: cloneable, this is just copied; unguarded against mods
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private Dictionary pubidMapping;
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/**
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* Constructs a resolver which understands how to map PUBLIC identifiers
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* to other URIs, typically for local copies of standard DTD components.
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*
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* @param dictionary maps PUBLIC identifiers to URIs. This is not
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* copied; subsequent modifications will be reported through the
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* resolution operations.
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*/
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public Resolver (Dictionary dict)
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{ pubidMapping = dict; }
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// FIXME: want notion of a "system default" resolver, presumably
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// loaded with all sorts of useful stuff. At the same time need
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// a notion of resolver chaining (failure --> next) so that subsystems
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// can set up things that won't interfere with other ones.
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/**
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* This parses most MIME content type strings that have <em>charset=...</em>
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* encoding declarations to and returns the specified encoding. This
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* conforms to RFC 3023, and is useful when constructing InputSource
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* objects from URLConnection objects or other objects using MIME
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* content typing.
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*
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* @param contentType the MIME content type that will be parsed; must
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* not be null.
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* @return the appropriate encoding, or null if the content type is
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* not text and there's no <code>charset=...</code> attribute
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*/
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static public String getEncoding (String contentType)
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{
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// currently a dumb parsing algorithm that works "mostly" and handles
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// ..anything...charset=ABC
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// ..anything...charset=ABC;otherAttr=DEF
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// ..anything...charset=ABC (comment);otherAttr=DEF
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// ..anything...charset= "ABC" (comment);otherAttr=DEF
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int temp;
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String encoding;
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String defValue = null;
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if (contentType.startsWith ("text/"))
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defValue = contentType.startsWith ("text/html")
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? "ISO-8859-1" : "US-ASCII";
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// Assumes 'charset' is only an attribute name, not part
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// of a value, comment, or other attribute name
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// ALSO assumes no escaped values like "\;" or "\)"
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if ((temp = contentType.indexOf ("charset")) != -1) {
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// strip out everything up to '=' ...
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temp = contentType.indexOf ('=', temp);
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if (temp == -1)
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return defValue;
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encoding = contentType.substring (temp + 1);
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// ... and any subsequent attributes
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if ((temp = encoding.indexOf (';')) != -1)
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encoding = encoding.substring (0, temp);
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// ... and any comments after value
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if ((temp = encoding.indexOf ('(')) != -1)
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encoding = encoding.substring (0, temp);
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// ... then whitespace, and any (double) quotes
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encoding = encoding.trim ();
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if (encoding.charAt (0) == '"')
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encoding = encoding.substring (1, encoding.length () - 1);
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} else
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encoding = defValue;
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return encoding;
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}
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/**
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* Uses a local dictionary of public identifiers to resolve URIs,
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* normally with the goal of minimizing network traffic or latencies.
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*/
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public InputSource resolveEntity (String publicId, String systemId)
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throws IOException, SAXException
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{
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InputSource retval = null;
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String uri;
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if (publicId != null
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&& ((uri = (String) pubidMapping.get (publicId)) != null)) {
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retval = new InputSource (uri);
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retval.setPublicId (publicId);
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}
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// Could do URN resolution here
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// URL resolution always done by parser
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// FIXME: chain to "next" resolver
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return retval;
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}
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}
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