Java tutorial
import java.io.File; import java.net.URL; import java.util.ArrayList; import java.util.Iterator; import java.util.List; import java.util.StringTokenizer; /* * JCommon : a free general purpose class library for the Java(tm) platform * * * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors. * * Project Info: http://www.jfree.org/jcommon/index.html * * This library is free software; you can redistribute it and/or modify it * under the terms of the GNU Lesser General Public License as published by * the Free Software Foundation; either version 2.1 of the License, or * (at your option) any later version. * * This library is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public * License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, * USA. * * [Java is a trademark or registered trademark of Sun Microsystems, Inc. * in the United States and other countries.] * * ------------ * IOUtils.java * ------------ * (C)opyright 2002-2004, by Thomas Morgner and Contributors. * * Original Author: Thomas Morgner; * Contributor(s): David Gilbert (for Object Refinery Limited); * * $Id: IOUtils.java,v 1.8 2009/01/22 08:34:58 taqua Exp $ * * Changes * ------- * 26-Jan-2003 : Initial version * 23-Feb-2003 : Documentation * 25-Feb-2003 : Fixed Checkstyle issues (DG); * 29-Apr-2003 : Moved to jcommon * 04-Jan-2004 : Fixed JDK 1.2.2 issues with createRelativeURL; * added support for query strings within these urls (TM); */ /** * The IOUtils provide some IO related helper methods. * * @author Thomas Morgner. */ public class Main { /** * Checks, whether the URL uses a file based protocol. * * @param url the url. * @return true, if the url is file based. */ private boolean isFileStyleProtocol(final URL url) { if (url.getProtocol().equals("http")) { return true; } if (url.getProtocol().equals("https")) { return true; } if (url.getProtocol().equals("ftp")) { return true; } if (url.getProtocol().equals("file")) { return true; } if (url.getProtocol().equals("jar")) { return true; } return false; } /** * Transforms the name list back into a single string, separated with "/". * * @param name the name list. * @param query the (optional) query for the URL. * @return the constructed name. */ private String formatName(final List name, final String query) { final StringBuffer b = new StringBuffer(); final Iterator it = name.iterator(); while (it.hasNext()) { b.append(it.next()); if (it.hasNext()) { b.append("/"); } } if (query != null) { b.append('?'); b.append(query); } return b.toString(); } /** * Checks, whether the URL points to the same service. A service is equal * if the protocol, host and port are equal. * * @param url a url * @param baseUrl an other url, that should be compared. * @return true, if the urls point to the same host and port and use the * same protocol, false otherwise. */ private boolean isSameService(final URL url, final URL baseUrl) { if (!url.getProtocol().equals(baseUrl.getProtocol())) { return false; } if (!url.getHost().equals(baseUrl.getHost())) { return false; } if (url.getPort() != baseUrl.getPort()) { return false; } return true; } /** * Parses the given name and returns the name elements as List of Strings. * * @param name the name, that should be parsed. * @return the parsed name. */ private List parseName(final String name) { final ArrayList list = new ArrayList(); final StringTokenizer strTok = new StringTokenizer(name, "/"); while (strTok.hasMoreElements()) { final String s = (String) strTok.nextElement(); if (s.length() != 0) { list.add(s); } } return list; } /** * Compares both name lists, and returns the last common index shared * between the two lists. * * @param baseName the name created using the base url. * @param urlName the target url name. * @return the number of shared elements. */ private int startsWithUntil(final List baseName, final List urlName) { final int minIdx = Math.min(urlName.size(), baseName.size()); for (int i = 0; i < minIdx; i++) { final String baseToken = (String) baseName.get(i); final String urlToken = (String) urlName.get(i); if (!baseToken.equals(urlToken)) { return i; } } return minIdx; } /** * Returns <code>true</code> if the URL represents a path, and * <code>false</code> otherwise. * * @param baseURL the URL. * * @return A boolean. */ private boolean isPath(final URL baseURL) { if (getPath(baseURL).endsWith("/")) { return true; } else if (baseURL.getProtocol().equals("file")) { final File f = new File(getPath(baseURL)); try { if (f.isDirectory()) { return true; } } catch (SecurityException se) { // ignored ... } } return false; } /** * Implements the JDK 1.3 method URL.getPath(). The path is defined * as URL.getFile() minus the (optional) query. * * @param url the URL * @return the path */ private String getQuery(final URL url) { final String file = url.getFile(); final int queryIndex = file.indexOf('?'); if (queryIndex == -1) { return null; } return file.substring(queryIndex + 1); } /** * Implements the JDK 1.3 method URL.getPath(). The path is defined * as URL.getFile() minus the (optional) query. * * @param url the URL * @return the path */ private String getPath(final URL url) { final String file = url.getFile(); final int queryIndex = file.indexOf('?'); if (queryIndex == -1) { return file; } return file.substring(0, queryIndex); } /** * Creates a relative url by stripping the common parts of the the url. * * @param url the to be stripped url * @param baseURL the base url, to which the <code>url</code> is relative * to. * @return the relative url, or the url unchanged, if there is no relation * beween both URLs. */ public String createRelativeURL(final URL url, final URL baseURL) { if (url == null) { throw new NullPointerException("content url must not be null."); } if (baseURL == null) { throw new NullPointerException("baseURL must not be null."); } if (isFileStyleProtocol(url) && isSameService(url, baseURL)) { // If the URL contains a query, ignore that URL; do not // attemp to modify it... final List urlName = parseName(getPath(url)); final List baseName = parseName(getPath(baseURL)); final String query = getQuery(url); if (!isPath(baseURL)) { baseName.remove(baseName.size() - 1); } // if both urls are identical, then return the plain file name... if (url.equals(baseURL)) { return (String) urlName.get(urlName.size() - 1); } int commonIndex = startsWithUntil(urlName, baseName); if (commonIndex == 0) { return url.toExternalForm(); } if (commonIndex == urlName.size()) { // correct the base index if there is some weird mapping // detected, // fi. the file url is fully included in the base url: // // base: /file/test/funnybase // file: /file/test // // this could be a valid configuration whereever virtual // mappings are allowed. commonIndex -= 1; } final ArrayList retval = new ArrayList(); if (baseName.size() >= urlName.size()) { final int levels = baseName.size() - commonIndex; for (int i = 0; i < levels; i++) { retval.add(".."); } } retval.addAll(urlName.subList(commonIndex, urlName.size())); return formatName(retval, query); } return url.toExternalForm(); } }