--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/artifacts-common/src/main/java/org/dive4elements/artifacts/common/utils/Config.java	Thu Apr 25 10:53:15 2013 +0200
@@ -0,0 +1,276 @@
+/*
+ * 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.artifacts.common.utils;
+
+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 :