ControllerEnvironment.java

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package net.java.games.input;

import java.io.File;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.logging.Logger;

/**
 * A ControllerEnvironment represents a collection of controllers that are
 * physically or logically linked.  By default, this corresponds to the
 * environment for the local machine.
 * <p>
 * In this reference implementation, this class can also be used to register
 * controllers with the default environment as "plug-ins".  A plug-in is
 * created by subclassing ControllerEnvironment with a class that has a public
 * no-argument constructor, implements the net.java.games.util.plugins.Plugin
 * interface and has a name ending in "Plugin".  
 * (See net.java.games.input.DirectInputEnvironmentPlugin in the DXplugin
 *  part of the source tree for an example.)
 *
 * When the DefaultControllerEnvrionment is instanced it uses the plugin library
 * to look for Plugins in both [java.home]/lib/controller and 
 * [user.dir]/controller.  This allows controller plugins to be installed either
 * globally for the entire Java environment or locally for just one particular
 * Java app.
 *
 * For more information on the organization of plugins within the controller
 * root directories, see net.java.games.util.plugins.Plugins (Note the
 * plural -- "Plugins" not "Plugin" which is just a marker interface.)
 *
 */
public abstract class ControllerEnvironment {
    static void logln(String msg) {
		log(msg + "\n");
	}

    static void log(String msg) {
		Logger.getLogger(ControllerEnvironment.class.getName()).info(msg);
	}

    /**
     * The default controller environment
     */
    private static ControllerEnvironment defaultEnvironment =
        new DefaultControllerEnvironment();
    
    /**
     * List of controller listeners
     */
    protected final ArrayList controllerListeners = new ArrayList();
    
    /**
     * Protected constructor for subclassing.
     */
    protected ControllerEnvironment() {
    }
    
    /**
     * Returns a list of all controllers available to this environment,
     * or an empty array if there are no controllers in this environment.
     */
    public abstract Controller[] getControllers();
    
    /**
     * Adds a listener for controller state change events.
     */
    public void addControllerListener(ControllerListener l) {
        assert l != null;
        controllerListeners.add(l);
    }
    
    /**
     * Returns the isSupported status of this environment.
     * What makes an environment supported or not is up to the
     * particular plugin, but may include OS or available hardware.
     */
    public abstract boolean isSupported();
    
    /**
     * Removes a listener for controller state change events.
     */
    public void removeControllerListener(ControllerListener l) {
        assert l != null;
        controllerListeners.remove(l);
    }
    
    /**
     * Creates and sends an event to the controller listeners that a controller
     * has been added.
     */
    protected void fireControllerAdded(Controller c) {
        ControllerEvent ev = new ControllerEvent(c);
        Iterator it = controllerListeners.iterator();
        while (it.hasNext()) {
            ((ControllerListener)it.next()).controllerAdded(ev);
        }
    }
    
    /**
     * Creates and sends an event to the controller listeners that a controller
     * has been lost.
     */
    protected void fireControllerRemoved(Controller c) {
        ControllerEvent ev = new ControllerEvent(c);
        Iterator it = controllerListeners.iterator();
        while (it.hasNext()) {
            ((ControllerListener)it.next()).controllerRemoved(ev);
        }
    }
    
    /**
     * Returns the default environment for input controllers.
     * This usually corresponds to the environment for the local machine.
     */
    public static ControllerEnvironment getDefaultEnvironment() {
        return defaultEnvironment;
    }
} // ControllerEnvironment