Application: gvSIG desktop » Library: org.gvsig.tools

/* gvSIG. Geographic Information System of the Valencian Government

 *

 * Copyright (C) 2007-2008 Infrastructures and Transports Department

 * of the Valencian Government (CIT)

 * 

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version 2

 * of the License, or (at your option) any later version.

 * 

 * 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 for more details.

 * 

 * You should have received a copy of the GNU 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.

 * 

 */

/*

 * AUTHORS (In addition to CIT):

 * 2008 {DiSiD Technologies}   {Create a base Locator implementation}

 */

package org.gvsig.tools.library;

import java.util.HashSet;

import java.util.Set;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

/**

 * Base Library implementation, checking that a Library is initialized and

 * postInitialized only once.

 * 

 * Also adds initialization logging.

 * 

 * @author <a href="mailto:cordin@disid.com">C?sar Ordi?ana</a>

 * @author jjdelcerro

 */

public abstract class AbstractLibrary implements Library {

    private static Set initialized = new HashSet();

    private static Set postInitialized = new HashSet();

    private static final int DEFAULT_PRIORITY = 0;

    private Set requireds = null;

    private Class library;

    private String type;

    private int priority = DEFAULT_PRIORITY;

    /**

     * Association between a library class and its type.

     * 

     * @author gvSIG team

     */

    public static class Required {

        Class library;

        String type;

        private boolean added = false;

        Required(Class library, String type) {

            this.library = library;

            this.type = type;

        }

        public Class getLibrary() {

            return this.library;

        }

        public String getType() {

            return this.type;

        }

        public String toString() {

            return this.library.toString() + ":"

                + (this.type == null ? "UNDEFINED" : this.type.toUpperCase());

        }

        /**

         * @return the added

         */

        public boolean isAdded() {

            return added;

        }

        /**

         * @param added

         *            the added to set

         */

        public void setAdded(boolean added) {

            this.added = added;

        }

    }

    /**

     * Empty constructor.

     */

    protected AbstractLibrary() {

        // Nothing to do

    }

    /**

     * Creates a new library registering with type of library it is: API or

     * implementation of a library.

     * <p>

     * When it is an API library, the class will be itself.

     * </p>

     * 

     * @param library

     *            the library class we relate to

     * @param type

     *            the library type. See {@link TYPE}.

     * @deprecated to be removed in the 4.x version. Use the

     *             {@link #AbstractLibrary()} empty constructor and override the

     *             {@link #doRegistration()} method instead.

     * @see #AbstractLibrary()

     */

    protected AbstractLibrary(Class library, String type) {

        registerAs(library, type);

    }

    /**

     * Creates a new library registering it as an implementation.

     * A priority is also provided just in case there is another

     * implementation available, so the one with the highest priority

     * will be the one used.

     * 

     * @param library

     *            the library class we relate to

     * @param priority

     *            the priority of the library against other implementations

     *            of the same library

     * @deprecated to be removed in the 4.x version. Use the

     *             {@link #AbstractLibrary()} empty constructor and override the

     *             {@link #doRegistration()} method instead.

     * @see #AbstractLibrary()

     */

    protected AbstractLibrary(Class library, int priority) {

        registerAsImplementationOf(library, priority);

    }

    public Set getRequireds() {

        return this.requireds;

    }

    /**

     * Returns the name of the current Library

     */

    public Class getLibrary() {

        return this.library;

    }

    public String getType() {

        return this.type;

    }

    public int getPriority() {

        return this.priority;

    }

    /**

     * Adds a required library, so it is initialized before the current one.

     * 

     * @param library

     *            the required library

     * @param type

     *            the type of the required library

     * @deprecated use the {@link #require(Class)} method instead, as you may

     *             have problems if the type specified is not correct. Moreover,

     *             this is not needed.

     */

    public synchronized final void require(Class library, String type) {

        doRequire(library, type);

    }

    /**

     * Adds a required library, so it is initialized before the current one.

     * 

     * @param library

     *            the required library

     */

    public synchronized final void require(Class library) {

        doRequire(library, null);

    }

    private void doRequire(Class library, String type) {

        if (requireds == null) {

            this.requireds = new HashSet();

        }

        this.requireds.add(new Required(library, type));

    }

    /**

     * Registers the library with type of library it is: API or

     * implementation of a library.

     * <p>

     * When it is an API library, the class will be itself.

     * </p>

     * 

     * @param library

     *            the library class we relate to

     * @param type

     *            the library type. See {@link TYPE}.

     */

    protected synchronized final void registerAs(Class library, String type) {

        this.library = library;

        this.type = type;

        if (this.library != null) {

            if (!Library.class.isAssignableFrom(library)) {

                throw new IllegalArgumentException(

                    "Given class is not a Library: " + library);

            }

            // Add default dependencies between services, implementation and API

            if (!Library.TYPE.API.equals(type)) {

                doRequire(this.library, Library.TYPE.API);

                if (Library.TYPE.SERVICE.equals(type)) {

                    doRequire(this.library, Library.TYPE.IMPL);

                }

            }

        }

    }

    /**

     * Registers the library as an API one.

     * 

     * @param library

     *            the library class we relate to

     */

    protected synchronized final void registerAsAPI(Class library) {

        registerAs(library, TYPE.API);

    }

    /**

     * Registers the library as an implementation of an API library, with the

     * default priority.

     * 

     * @param library

     *            the library class we relate to

     */

    protected synchronized final void registerAsImplementationOf(Class library) {

        registerAsImplementationOf(library, DEFAULT_PRIORITY);

    }

    /**

     * Registers the library as an implementation of an API library.

     * A priority is also provided just in case there is another

     * implementation available, so the one with the highest priority

     * will be the one used.

     * 

     * @param library

     *            the library class we relate to

     * @param priority

     *            the priority of the library against other implementations

     *            of the same library

     */

    protected synchronized final void registerAsImplementationOf(Class library,

        int priority) {

        registerAs(library, Library.TYPE.IMPL);

        this.priority = priority;

    }

    /**

     * Registers the library as a service or provider of an API library.

     * 

     * @param library

     *            the library class we relate to

     */

    protected synchronized final void registerAsServiceOf(Class library) {

        registerAs(library, TYPE.SERVICE);

    }

    public synchronized final void initialize() throws LibraryException {

        Logger logger = null;

        // Check if we have been already initialized

        String name = getClass().getName();

        if (initialized.contains(name)) {

            return;

        }

        logger = LoggerFactory.getLogger(this.getClass());

        logger

            .info("Initializing library '" + this.getClass().getName() + "'.");

        // Set the current Library as initialized

        initialized.add(name);

        doInitialize();

    }

    public synchronized final void postInitialize() throws LibraryException {

        Logger logger = null;

        // Check if we have been already postInitialized

        String name = getClass().getName();

        if (postInitialized.contains(name)) {

            return;

        }

        logger = LoggerFactory.getLogger(this.getClass());

        logger.info("PostInitializing library '" + this.getClass().getName()

            + "'.");

        doPostInitialize();

        // Set the current Library as postInitialized

        postInitialized.add(name);

    }

    public void doRegistration() {

        // Empty implementation so child classes may still use the registration

        // in its constructor

    }

    public boolean equals(Object obj) {

        return obj != null

            && getClass().getName().equals(obj.getClass().getName());

    }

    public int hashCode() {

        return getClass().getName().hashCode();

    }

    public String toString() {

        if (getType() == null) {

            return getClass().getName();

        }

        String relatedLibName =

            library == null ? getClass().getName() : library.getName();

        return getClass().getName() + " (" + getType().toUpperCase() + " of "

            + relatedLibName + ")";

    }

    /**

     * Performs all the initializations of the library, only related to himself:

     * register implementation classes through the Locator, start services, etc.

     * 

     * @throws LibraryException

     *             if there is an error while performing the initialization of

     *             the library

     */

    protected abstract void doInitialize() throws LibraryException;

    /**

     * Performs all the initializations or validations related to the library

     * dependencies, as getting references to objects through other libraries

     * Locators.

     * 

     * @throws LibraryException

     *             if there is an error while loading an implementation of the

     *             library

     */

    protected abstract void doPostInitialize() throws LibraryException;

}