mmeventhandler.java

来自「This is a resource based on j2me embedde」· Java 代码 · 共 86 行

/*
 *   
 *
 * Copyright  1990-2007 Sun Microsystems, Inc. All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
 * 
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version
 * 2 only, 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 version 2 for more details (a copy is
 * included at /legal/license.txt).
 * 
 * You should have received a copy of the GNU General Public License
 * version 2 along with this work; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 * 
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
 * Clara, CA 95054 or visit www.sun.com if you need additional
 * information or have any questions.
 */

package com.sun.mmedia;

import com.sun.midp.events.*;
import com.sun.midp.security.*;


/**
 * MMEventHandler is used by BasicPlayer to register an event handler.  
 */
public class MMEventHandler {

    /**
     * Inner class to request security token from SecurityInitializer.
     * SecurityInitializer should be able to check this inner class name.
     */
    static private class SecurityTrusted
        implements ImplicitlyTrustedClass {};

    /** This class has a different security domain than the MIDlet suite */
    private static SecurityToken classSecurityToken =
        SecurityInitializer.requestToken(new SecurityTrusted());

    /**
     * The EventListener to receive the MM events.
     */
    private static EventListener listener;

    /**
     * Initializes the security token for this class, so it can
     * perform actions that a normal MIDlet Suite cannot.
     *
     * @param token security token for this class.
     */
    public static void initSecurityToken(SecurityToken token) {
        if (classSecurityToken == null) {
            classSecurityToken = token;
        }
    }

    /**
     * Set the Event listener on the event queue.  
     * <br>
     * This method is made package-private so only classes from
     * com.sun.mmedia (BasicPlayer) can access it for security
     * reasons.
     *
     * @param l EventListener for the MM events.
     */
    static void setListener(EventListener l) {

	// This can only be set once.
	if (listener != null)
	    return;
	listener = l;
	
	EventQueue evtq = EventQueue.getEventQueue(classSecurityToken);
	evtq.registerEventListener(EventTypes.MMAPI_EVENT, listener);
    }
}