packagemanager.java

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/* ========================================================================
 * JCommon : a free general purpose class library for the Java(tm) platform
 * ========================================================================
 *
 * (C) Copyright 2000-2004, 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., 59 Temple Place, Suite 330,
 * Boston, MA 02111-1307, USA.
 *
 * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 
 * in the United States and other countries.]
 * 
 * -------------------
 * PackageManager.java
 * -------------------
 * (C)opyright 2003, 2004, by Thomas Morgner and Contributors.
 *
 * Original Author:  Thomas Morgner;
 * Contributor(s):   David Gilbert (for Object Refinery Limited);
 *
 * $Id: PackageManager.java,v 1.6 2005/06/01 14:12:28 taqua Exp $
 *
 * Changes
 * -------
 * 26-Jun-2003 : Initial version
 * 07-Jun-2004 : Added JCommon header (DG);
 * 
 */

package org.jfree.base.modules;

import java.io.PrintStream;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Iterator;

import org.jfree.base.AbstractBoot;
import org.jfree.base.config.HierarchicalConfiguration;
import org.jfree.base.config.PropertyFileConfiguration;
import org.jfree.base.log.PadMessage;
import org.jfree.util.Configuration;
import org.jfree.util.Log;
import org.jfree.util.ObjectUtilities;

/**
 * The PackageManager is used to load and configure the modules of JFreeReport.
 * Modules are used to extend the basic capabilities of JFreeReport by providing
 * a simple plugin-interface.
 * <p/>
 * Modules provide a simple capability to remove unneeded functionality from the
 * JFreeReport system and to reduce the overall code size. The modularisation provides
 * a very strict way of removing unnecessary dependencies beween the various packages.
 * <p/>
 * The package manager can be used to add new modules to the system or to check
 * the existence and state of installed modules.
 *
 * @author Thomas Morgner
 */
public final class PackageManager {
    /**
     * The PackageConfiguration handles the module level configuration.
     *
     * @author Thomas Morgner
     */
    public static class PackageConfiguration extends PropertyFileConfiguration {
        /**
         * DefaultConstructor. Creates a new package configuration.
         */
        public PackageConfiguration() {
            // nothing required
        }

        /**
         * The new configuartion will be inserted into the list of report configuration,
         * so that this configuration has the given report configuration instance as parent.
         *
         * @param config the new report configuration.
         */
        public void insertConfiguration(final HierarchicalConfiguration config) {
            super.insertConfiguration(config);
        }
    }


    /**
     * An internal constant declaring that the specified module was already loaded.
     */
    private static final int RETURN_MODULE_LOADED = 0;
    /**
     * An internal constant declaring that the specified module is not known.
     */
    private static final int RETURN_MODULE_UNKNOWN = 1;
    /**
     * An internal constant declaring that the specified module produced an error while loading.
     */
    private static final int RETURN_MODULE_ERROR = 2;


    /**
     * The module configuration instance that should be used to store module
     * properties. This separates the user defined properties from the implementation
     * defined properties.
     */
    private final PackageConfiguration packageConfiguration;

    /**
     * A list of all defined modules.
     */
    private final ArrayList modules;
    /**
     * A list of module name definitions.
     */
    private final ArrayList initSections;

    /** The boot implementation for which the modules are managed. */
    private AbstractBoot booter;

    /** The instances of all modules for all booters. */
    private static HashMap instances;

    /**
     * Creates a package manager instance.
     *
     * @param booter the booter.
     * @return A package manager.
     */
    public static PackageManager createInstance(final AbstractBoot booter) {
        PackageManager manager;
        if (instances == null) {
            instances = new HashMap();
            manager = new PackageManager(booter);
            instances.put(booter, manager);
            return manager;
        }
        manager = (PackageManager) instances.get(booter);
        if (manager == null) {
            manager = new PackageManager(booter);
            instances.put(booter, manager);
        }
        return manager;
    }

    /**
     * Creates a new package manager.
     *
     * @param booter the booter (<code>null</code> not permitted).
     */
    private PackageManager(final AbstractBoot booter) {
        if (booter == null) {
            throw new NullPointerException();
        }
        this.booter = booter;
        this.packageConfiguration = new PackageConfiguration();
        this.modules = new ArrayList();
        this.initSections = new ArrayList();
    }

    /**
     * Checks, whether a certain module is available.
     *
     * @param moduleDescription the module description of the desired module.
     * @return true, if the module is available and the version of the module
     *         is compatible, false otherwise.
     */
    public boolean isModuleAvailable(final ModuleInfo moduleDescription) {
        final PackageState[] packageStates =
            (PackageState[]) this.modules.toArray(new PackageState[this.modules.size()]);
        for (int i = 0; i < packageStates.length; i++) {
            final PackageState state = packageStates[i];
            if (state.getModule().getModuleClass().equals(moduleDescription.getModuleClass())) {
                return (state.getState() == PackageState.STATE_INITIALIZED);
            }
        }
        return false;
    }

    /**
     * Loads all modules mentioned in the report configuration starting with
     * the given prefix. This method is used during the boot process of
     * JFreeReport. You should never need to call this method directly.
     *
     * @param modulePrefix the module prefix.
     */
    public void load(final String modulePrefix) {
        if (this.initSections.contains(modulePrefix)) {
            return;
        }
        this.initSections.add(modulePrefix);

        final Configuration config = this.booter.getGlobalConfig();
        final Iterator it = config.findPropertyKeys(modulePrefix);
        while (it.hasNext()) {
            final String key = (String) it.next();
            if (key.endsWith(".Module")) {
                addModule(config.getConfigProperty(key));
            }
        }
        Log.debug("Loaded a total of " + this.modules.size() + " modules under prefix: " + modulePrefix);
    }

    /**
     * Initializes all previously uninitialized modules. Once a module is initialized,
     * it is not re-initialized a second time.
     */
    public synchronized void initializeModules() {
        // sort by subsystems and dependency
        PackageSorter.sort(this.modules);

        for (int i = 0; i < this.modules.size(); i++) {
            final PackageState mod = (PackageState) this.modules.get(i);
            if (mod.configure(this.booter)) {
                Log.debug(new Log.SimpleMessage("Conf: ",
                    new PadMessage(mod.getModule().getModuleClass(), 70),
                    " [", mod.getModule().getSubSystem(), "]"));
            }
        }

        for (int i = 0; i < this.modules.size(); i++) {
            final PackageState mod = (PackageState) this.modules.get(i);
            if (mod.initialize(this.booter)) {
                Log.debug(new Log.SimpleMessage("Init: ",
                    new PadMessage(mod.getModule().getModuleClass(), 70),
                    " [", mod.getModule().getSubSystem(), "]"));
            }
        }
    }

    /**
     * Adds a module to the package manager.
     * Once all modules are added, you have to call initializeModules()
     * to configure and initialize the new modules.
     *
     * @param modClass the module class
     */
    public synchronized void addModule(final String modClass) {
        final ArrayList loadModules = new ArrayList();
        final ModuleInfo modInfo = new DefaultModuleInfo
            (modClass, null, null, null);
        if (loadModule(modInfo, new ArrayList(), loadModules, false)) {
            for (int i = 0; i < loadModules.size(); i++) {
                final Module mod = (Module) loadModules.get(i);
                this.modules.add(new PackageState(mod));
            }
        }
    }

    /**
     * Checks, whether the given module is already loaded in either the given
     * tempModules list or the global package registry. If tmpModules is null,
     * only the previously installed modules are checked.
     *
     * @param tempModules a list of previously loaded modules.
     * @param module      the module specification that is checked.
     * @return true, if the module is already loaded, false otherwise.
     */
    private int containsModule(final ArrayList tempModules, final ModuleInfo module) {
        if (tempModules != null) {
            final ModuleInfo[] mods = (ModuleInfo[])
                tempModules.toArray(new ModuleInfo[tempModules.size()]);
            for (int i = 0; i < mods.length; i++) {
                if (mods[i].getModuleClass().equals(module.getModuleClass())) {
                    return RETURN_MODULE_LOADED;
                }
            }
        }

        final PackageState[] packageStates =
            (PackageState[]) this.modules.toArray(new PackageState[this.modules.size()]);
        for (int i = 0; i < packageStates.length; i++) {
            if (packageStates[i].getModule().getModuleClass().equals(module.getModuleClass())) {
                if (packageStates[i].getState() == PackageState.STATE_ERROR) {
                    return RETURN_MODULE_ERROR;
                }
                else {
                    return RETURN_MODULE_LOADED;
                }
            }