Java tutorial
/* * Copyright (C) 2007 SQL Explorer Development Team * http://sourceforge.net/projects/eclipsesql * * This program 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ package net.sourceforge.sqlexplorer.dbproduct; import java.io.File; import java.io.FileInputStream; import java.io.FileWriter; import java.io.IOException; import java.io.InputStream; import java.net.URL; import java.util.Collection; import java.util.HashMap; import net.sourceforge.sqlexplorer.ApplicationFiles; import net.sourceforge.sqlexplorer.ExplorerException; import net.sourceforge.sqlexplorer.plugin.SQLExplorerPlugin; import net.sourceforge.sqlexplorer.util.URLUtil; import org.dom4j.Document; import org.dom4j.Element; import org.dom4j.io.OutputFormat; import org.dom4j.io.SAXReader; import org.dom4j.io.XMLWriter; import org.dom4j.tree.DefaultElement; /** * Provides access to the list of drivers, persisting their configuration in the * Eclipse workspace; restoring to defaults is also supported. * * This is part of the rewrite of SQLAlias, which was originally taken from * SquirrelSQL; the old DriverModel (via DataCache) used parts of Squirrel which no * longer exist (even in the SquirrelSQL CVS on Sourceforge) and are effectively * undocumented. Changes needed to fix bugs relating to transactions and multiple * logons per alias meant that keeping the old code became unmaintainable, hence the * sweeping rewrite. * * @author John Spackman */ public class DriverManager { public static final String DRIVER = "driver"; public static final String DRIVER_CLASS = "driver-class"; public static final String DRIVERS = "drivers"; public static final String ID = "id"; public static final String JARS = "jars"; public static final String JAR = "jar"; public static final String NAME = "name"; public static final String URL = "url"; // List of drivers, indexed by ID private HashMap<String, ManagedDriver> drivers = new HashMap<String, ManagedDriver>(); // Highest ID, used when creating a new unique ID private int highestId; /** * Restores drivers to their default location * @throws ExplorerException */ public void restoreDrivers() throws ExplorerException { try { drivers.clear(); highestId = 0; URL url = URLUtil.getResourceURL("default_drivers.xml"); loadDrivers(url.openStream()); } catch (IOException e) { throw new ExplorerException(e); } } /** * Loads drivers from the users preferences * @throws ExplorerException */ public void loadDrivers() throws ExplorerException { try { File file = new File(ApplicationFiles.USER_DRIVER_FILE_NAME); if (!file.exists()) { restoreDrivers(); saveDrivers(); return; } loadDrivers(new FileInputStream(file)); } catch (IOException e) { throw new ExplorerException("Cannot load user drivers: " + e.getMessage(), e); } } /** * Loads driver definition from a given location * @param input * @throws ExplorerException */ protected void loadDrivers(InputStream input) throws ExplorerException { try { SAXReader reader = new SAXReader(); Document doc = reader.read(input); Element root = doc.getRootElement(); if (root.getName().equals("Beans")) root = convertFromV3(root); for (Element driverElem : root.elements(DRIVER)) { ManagedDriver driver = new ManagedDriver(driverElem); addDriver(driver); } } catch (Exception e) { throw new ExplorerException(e); } } /** * Saves the drivers back to disk * @throws ExplorerException */ public void saveDrivers() throws ExplorerException { Element root = new DefaultElement(DRIVERS); for (ManagedDriver driver : drivers.values()) root.add(driver.describeAsXml()); try { FileWriter writer = new FileWriter(new File(ApplicationFiles.USER_DRIVER_FILE_NAME)); OutputFormat format = OutputFormat.createPrettyPrint(); XMLWriter xmlWriter = new XMLWriter(writer, format); xmlWriter.write(root); writer.flush(); writer.close(); } catch (IOException e) { throw new ExplorerException(e); } } /** * Adds a new Driver * @param driver */ public void addDriver(ManagedDriver driver) { if (driver.getId() == null || driver.getId().trim().length() == 0) throw new IllegalArgumentException("Driver has an invalid ID"); if (drivers.get(driver.getId()) != null) throw new IllegalArgumentException("Driver with id of " + driver.getId() + " already exists"); drivers.put(driver.getId(), driver); // Try and update our highest ID; if it's not a valid number then we // just ignore it try { int id = Integer.parseInt(driver.getId()); if (id > 0 && id > highestId) highestId = id; } catch (NumberFormatException e) { // Nothing } } /** * Removes a driver * @param driver */ public void removeDriver(ManagedDriver driver) { drivers.remove(driver.getId()); } /** * Returns a driver with a given ID * @param id * @return */ public ManagedDriver getDriver(String id) { return drivers.get(id); } /** * Returns all the drivers * @return */ public Collection<ManagedDriver> getDrivers() { return drivers.values(); } /** * Allocates a new Unique ID for creating drivers with * @return */ public String createUniqueId() { return Integer.toString(++highestId); } /** * Converts from the old v3 format (which is a JavaBean encoding) * @param root * @return */ protected Element convertFromV3(Element root) { Element result = new DefaultElement(DRIVERS); for (Element elem : root.elements("Bean")) { String str; Element driver = result.addElement(DRIVER); try { str = elem.element("identifier").elementText("string"); driver.addAttribute(ID, str); str = elem.elementText("driverClass"); if (str != null) driver.addElement(DRIVER_CLASS).setText(str); str = elem.elementText("name"); driver.addElement(NAME).setText(str); str = elem.elementText("url"); driver.addElement(URL).setText(str); Element jars = driver.addElement(JARS); Element jarFileNames = elem.element("jarFileNames"); for (Element jarBeanElem : jarFileNames.elements("Bean")) { str = jarBeanElem.elementText("string"); if (str != null && str.trim().length() > 0) jars.addElement(JAR).setText(str); } } catch (IllegalArgumentException e) { SQLExplorerPlugin.error("Error loading v3 driver " + driver.attributeValue(ID), e); throw e; } } return result; } }