jtopplugin.java

一个小公司要求给写的很简单的任务管理系统。

/*
 * @(#)JTopPlugin.java	1.2  06/05/08
 *
 * Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * -Redistribution of source code must retain the above copyright notice, this
 *  list of conditions and the following disclaimer.
 *
 * -Redistribution in binary form must reproduce the above copyright notice,
 *  this list of conditions and the following disclaimer in the documentation
 *  and/or other materials provided with the distribution.
 *
 * Neither the name of Sun Microsystems, Inc. or the names of contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN")
 * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
 * AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
 * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
 * REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL,
 * INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY
 * OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
 * EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 *
 * You acknowledge that this software is not designed, licensed or intended
 * for use in the design, construction, operation or maintenance of any
 * nuclear facility.
 */

/*
 * @(#)JTopPlugin.java	1.2 06/05/08
 *
 * Example of a JConsole Plugin.  This loads JTop as a JConsole tab.
 *
 * @author Mandy Chung
 */

import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.util.LinkedHashMap;
import java.util.Map;
import javax.management.MBeanServerConnection;
import javax.swing.JPanel;
import javax.swing.SwingWorker;

import com.sun.tools.jconsole.JConsolePlugin;
import com.sun.tools.jconsole.JConsoleContext;
import com.sun.tools.jconsole.JConsoleContext.ConnectionState;

/**
 * JTopPlugin is a subclass to com.sun.tools.jconsole.JConsolePlugin
 *
 * JTopPlugin is loaded and instantiated by JConsole.  One instance
 * is created for each window that JConsole creates. It listens to
 * the connected property change so that it will update JTop with
 * the valid MBeanServerConnection object.  JTop is a JPanel object
 * displaying the thread and its CPU usage information.
 */
public class JTopPlugin extends JConsolePlugin implements PropertyChangeListener
{
    private JTop jtop = null;
    private Map<String, JPanel> tabs = null;

    public JTopPlugin() {
        // register itself as a listener
        addContextPropertyChangeListener(this);
    }

    /*
     * Returns a JTop tab to be added in JConsole.
     */
    public synchronized Map<String, JPanel> getTabs() {
        if (tabs == null) {
            jtop = new JTop();
            jtop.setMBeanServerConnection(
                getContext().getMBeanServerConnection());
            // use LinkedHashMap if you want a predictable order
            // of the tabs to be added in JConsole
            tabs = new LinkedHashMap<String, JPanel>();
            tabs.put("JTop", jtop);
        }
        return tabs;
    }

    /*
     * Returns a SwingWorker which is responsible for updating the JTop tab.
     */
    public SwingWorker<?,?> newSwingWorker() {
        return jtop.newSwingWorker();    
    }

    // You can implement the dispose() method if you need to release 
    // any resource when the plugin instance is disposed when the JConsole
    // window is closed.
    //
    // public void dispose() {
    // }
                                                                    
    /*
     * Property listener to reset the MBeanServerConnection
     * at reconnection time.
     */
    public void propertyChange(PropertyChangeEvent ev) {
        String prop = ev.getPropertyName();
        if (prop == JConsoleContext.CONNECTION_STATE_PROPERTY) {
            ConnectionState oldState = (ConnectionState)ev.getOldValue();
            ConnectionState newState = (ConnectionState)ev.getNewValue();
            // JConsole supports disconnection and reconnection
            // The MBeanServerConnection will become invalid when
            // disconnected. Need to use the new MBeanServerConnection object
            // created at reconnection time.
            if (newState == ConnectionState.CONNECTED && jtop != null) {
                jtop.setMBeanServerConnection(
                    getContext().getMBeanServerConnection()); 
            }
        }
    }
}