Mercurial > dive4elements > framework
view artifact-database/src/main/java/de/intevation/artifactdatabase/Config.java @ 114:19b86e27d0c3
New XPath constants and methods that retrieve important nodes of the DESCRIBE document.
artifacts/trunk@1328 c6561f87-3c4e-4783-a992-168aeb5c3f6f
author | Ingo Weinzierl <ingo.weinzierl@intevation.de> |
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date | Fri, 18 Feb 2011 14:21:32 +0000 |
parents | 933bbc9fc11f |
children |
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/* * Copyright (c) 2010 by Intevation GmbH * * This program is free software under the LGPL (>=v2.1) * Read the file LGPL.txt coming with the software for details * or visit http://www.gnu.org/licenses/ if it does not exist. */ package de.intevation.artifactdatabase; import java.io.File; import java.io.IOException; import javax.xml.namespace.QName; import javax.xml.parsers.DocumentBuilderFactory; import javax.xml.parsers.ParserConfigurationException; import javax.xml.xpath.XPathConstants; import org.apache.log4j.Logger; import org.w3c.dom.Document; import org.w3c.dom.Node; import org.w3c.dom.NodeList; import org.xml.sax.SAXException; /** * The central access to the configuration of the artifact database. * This class provides some static methods to access the central * configuration XML file via XPath. * * @author <a href="mailto:sascha.teichmann@intevation.de">Sascha L. Teichmann</a> */ public final class Config { private static Logger logger = Logger.getLogger(Config.class); /** * System property name where to find the configuration directory. */ public static final String CONFIG_DIR = "artifact.database.dir"; /** * Default path to the configuration directory if none * was specified by the CONFIG_DIR system property. */ public static final File CONFIG_DIR_DEFAULT = new File(new File(System.getProperty("user.home", System.getProperty("user.dir", "."))), ".artifactdb"); /** * Name of the central configuration XML file. */ public static final String CONFIG_FILE = "conf.xml"; /** * Name of the configuration filename alias to be use * within the configuration. This alias is replaced by * the real path. */ public static final String CONFIG_DIR_PLACEHOLDER = "${artifacts.config.dir}"; private static Document config; private Config() { } /** * Singleton access to the central XML configuration document. * @return The central XML configuration document. */ public static synchronized final Document getConfig() { if (config == null) { config = loadConfig(); } return config; } /** * Returns the path to the configuartion directory. If a path * was specified via the CONFIG_DIR system property this one * is used. Else it falls back to default configuration path. * @return The path to the configuartion directory. */ public static File getConfigDirectory() { String configDirString = System.getProperty(CONFIG_DIR); File configDir = configDirString != null ? new File(configDirString) : CONFIG_DIR_DEFAULT; if (!configDir.isDirectory()) { logger.warn("'" + configDir + "' is not a directory."); configDir = CONFIG_DIR_DEFAULT; } return configDir; } /** * Replaces the CONFIG_DIR_PLACEHOLDER alias with the real path * of the configuration directory. * @param path The path containing the CONFIG_DIR_PLACEHOLDER placeholder. * @return The path where the CONFIG_DIR_PLACEHOLDER placeholders are * replaced by the real path name. */ public static String replaceConfigDir(String path) { String configDir = getConfigDirectory().getAbsolutePath(); return path.replace(CONFIG_DIR_PLACEHOLDER, configDir); } private static Document loadConfig() { File configDir = getConfigDirectory(); File file = new File(configDir, CONFIG_FILE); if (!file.canRead() && !file.isFile()) { logger.error("Cannot read config file '" + file + "'."); return null; } try { DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance(); factory.setValidating(false); // XXX: This may change in future. return factory.newDocumentBuilder().parse(file); } catch (SAXException se) { logger.error(se.getLocalizedMessage(), se); } catch (ParserConfigurationException pce) { logger.error(pce.getLocalizedMessage(), pce); } catch (IOException ioe) { logger.error(ioe.getLocalizedMessage()); } return null; } /** * Convenience method to search within a given document tree via XPath. * See {@link XMLUtils#xpath(Object, String, QName) } for details. * @param root The object which is used as the root of the tree to * be searched in. * @param query The XPath query. * @param returnType The type of the result. * @return The result of type 'returnTyp' or null if something went * wrong during XPath evaluation. */ public static final Object getXPath( Object root, String query, QName returnType ) { return XMLUtils.xpath(root, query, returnType); } /** * Convenience method to search within the central configuration via XPath. * See {@link XMLUtils#xpath(Object, String, QName) } for details. * @param query The XPath query. * @param returnType The type of the result. * @return The result of type 'returnTyp' or null if something went * wrong during XPath evaluation. */ public static final Object getXPath(String query, QName returnType) { return XMLUtils.xpath(getConfig(), query, returnType); } /** * Convenience method to search for a node list within the central * configuation document via XPath. * @param query The XPath query. * @return The queried node list or null if something went * wrong during XPath evaluation. */ public static final NodeList getNodeSetXPath(String query) { return (NodeList)getXPath(query, XPathConstants.NODESET); } /** * Convenience method to search for a node within the central * configuation document via XPath. * @param query The XPath query. * @return The queried node or null if something went * wrong during XPath evaluation. */ public static final Node getNodeXPath(String query) { return (Node)getXPath(query, XPathConstants.NODE); } /** * Convenience method to search for a string within the central * configuation document via XPath. * @param xpath The XPath query. * @return The queried string or null if something went * wrong during XPath evaluation. */ public static final String getStringXPath(String xpath) { return getStringXPath(xpath, null); } /** * Convenience method to search for a string within the central * configuation document via XPath. * @param query The XPath query. * @param def The string to be returned if the search has no results. * @return The queried string or the default value if something went * wrong during XPath evaluation. */ public static final String getStringXPath(String query, String def) { String s = (String)getXPath(query, XPathConstants.STRING); return s == null || s.length() == 0 ? def : s; } /** * Convenience method to search for a node list within a given tree * via XPath. * @param root The root of the tree to be searched in. * @param query The XPath query. * @return The queried node list or null if something went * wrong during XPath evaluation. */ public static final NodeList getNodeSetXPath(Object root, String query) { return (NodeList)getXPath(root, query, XPathConstants.NODESET); } /** * Convenience method to search for a node within a given tree * via XPath. * @param root The root of the tree to be searched in. * @param query The XPath query. * @return The queried node or null if something went * wrong during XPath evaluation. */ public static final Node getNodeXPath(Object root, String query) { return (Node)getXPath(root, query, XPathConstants.NODE); } /** * Convenience method to search for a string within a given tree * via XPath. * @param root The root of the tree to be searched in. * @param xpath The XPath query. * @return The queried string or null if something went * wrong during XPath evaluation. */ public static final String getStringXPath(Object root, String xpath) { return getStringXPath(root, xpath, null); } /** * Convenience method to search for a string within a given tree * via XPath. * @param root The root of the tree to be searched in. * @param query xpath The XPath query. * @param def The string to be returned if the search has no results. * @return The queried string or the default value if something went * wrong during XPath evaluation. */ public static final String getStringXPath( Object root, String query, String def ) { String s = (String)getXPath(root, query, XPathConstants.STRING); return s == null || s.length() == 0 ? def : s; } } // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :