Java tutorial
/* * Jopr Management Platform * Copyright (C) 2005-2011 Red Hat, Inc. * All rights reserved. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License, version 2, as * published by the Free Software Foundation, and/or the GNU Lesser * General Public License, version 2.1, also as published by the Free * Software Foundation. * * This program 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 General Public License and the GNU Lesser General Public License * for more details. * * You should have received a copy of the GNU General Public License * and the GNU Lesser General Public License along with this program; * if not, write to the Free Software Foundation, Inc., * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ package org.rhq.plugins.jbosscache; import java.io.File; import java.io.FileOutputStream; import java.io.IOException; import java.util.List; import javax.management.MalformedObjectNameException; import javax.management.ObjectName; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.jdom.Document; import org.jdom.Element; import org.jdom.JDOMException; import org.jdom.input.SAXBuilder; import org.jdom.output.Format; import org.jdom.output.XMLOutputter; import org.rhq.core.domain.configuration.Configuration; import org.rhq.core.pluginapi.util.SelectiveSkippingEntityResolver; /** * A utility for creating or updating JBossCache 2.x XML configuration files. * * @author Heiko W. Rupp * @author Ian Springer */ public class CacheConfigurationHelper { private Log log = LogFactory.getLog(CacheConfigurationHelper.class); /** * Write a configuration to the cache * @param file File to write to * @param config The configuration to write * @param mbeanName The name of the cache mbean in the file * @param isUpdate Are we updating a file or creating a new one * @throws JDOMException * @throws IOException */ public void writeConfig(File file, Configuration config, String mbeanName, boolean isUpdate) throws JDOMException, IOException { Document doc; Element root; Element cacheMbean; String flavour = config.getSimple("Flavour").getStringValue(); boolean isTc = false; if (flavour != null && flavour.startsWith("tree")) { isTc = true; } if (isUpdate) { if (!file.exists() || !file.canWrite()) { throw new IllegalStateException("Can't update file, as it is not writeable."); } SAXBuilder builder = new SAXBuilder(); SelectiveSkippingEntityResolver entityResolver = SelectiveSkippingEntityResolver .getDtdAndXsdSkippingInstance(); builder.setEntityResolver(entityResolver); doc = builder.build(file); root = doc.getRootElement(); cacheMbean = findComponentElement(root, mbeanName); if (cacheMbean == null) { throw new IllegalStateException("File does not contain an MBean with name '" + mbeanName + "'."); } } else { // new file doc = new Document(); root = new Element("server"); doc.setRootElement(root); cacheMbean = new Element("mbean"); cacheMbean.setAttribute("name", mbeanName); root.addContent(cacheMbean); } if (isTc) { cacheMbean.setAttribute("code", "org.jboss.cache.TreeCache"); } else { cacheMbean.setAttribute("code", "org.jboss.cache.PojoCache"); } // Make sure 'depends' elements exist for the cache service's service dependencies. addJBossServiceDependsIfNotPresent(cacheMbean, "jboss:service=Naming"); addJBossServiceDependsIfNotPresent(cacheMbean, "jboss:service=TransactionManager"); // Add or update 'attribute' elements for each of the config props. for (String propName : config.getSimpleProperties().keySet()) { if (propName.equals("Flavour")) { // Skip this prop, which we already used above to set the mbean class. continue; } String propVal = config.getSimple(propName).getStringValue(); Element attribute = null; if (isUpdate) { // on update we need to find the existing element and update it attribute = findAttributeNodeWithName(cacheMbean, propName); } if (propVal == null) { // for a null value, delete the 'attribute' element if one exists to tell the mbean to use its internal // default value for that attribute if (attribute != null) { cacheMbean.removeContent(attribute); } } else { if (attribute == null) { // an 'attribute' element for this attribute does not yet exist - add one. attribute = new Element("attribute"); attribute.setAttribute("name", propName); cacheMbean.addContent(attribute); } attribute.setText(propVal); } } // TODO add the cluster config // now write the changes to disk FileOutputStream fos = null; try { fos = new FileOutputStream(file); XMLOutputter outputter = new XMLOutputter(Format.getPrettyFormat()); outputter.output(doc, fos); fos.flush(); } catch (IOException ioe) { log.error("Can't write the config : " + ioe); } finally { if (fos != null) { fos.close(); } } } private void addJBossServiceDependsIfNotPresent(Element mBeanElement, String serviceMBeanName) { boolean foundDepends = false; List dependsElements = mBeanElement.getChildren("depends"); for (Object dependsObj : dependsElements) { Element depends = (Element) dependsObj; if (depends.getText().equals(serviceMBeanName)) { foundDepends = true; break; } } if (!foundDepends) { Element depends = new Element("depends"); depends.setText(serviceMBeanName); mBeanElement.addContent(depends); } } /** * Find the <attribute name="XX"> node below base, where XX matches the input. * If no node is found, null is returned. * @param base The base element under which to search * @param propName The name attribute for which to search * @return The element found or null */ private Element findAttributeNodeWithName(Element base, String propName) { if (propName == null) { return null; } for (Object attrObj : base.getChildren("attribute")) { if (attrObj instanceof Element) { Element attr = (Element) attrObj; String nameAttrib = attr.getAttributeValue("name"); if (propName.equals(nameAttrib)) { return attr; } } } return null; } private Element findComponentElement(Element base, String mbeanName) { for (Object mbeanObj : base.getChildren("mbean")) { if (mbeanObj instanceof Element) { Element mbean = (Element) mbeanObj; // normalize the content of 'name' String nameAttrib = mbean.getAttributeValue("name"); try { ObjectName on = new ObjectName(nameAttrib); nameAttrib = on.getCanonicalName(); } catch (MalformedObjectNameException e) { log.warn("Can't canonicalize " + nameAttrib); } if (nameAttrib.equals(mbeanName)) return mbean; } } return null; } }