basejmxnotification.java

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package org.sadun.util.polling;

import java.io.File;
import java.io.IOException;
import java.lang.reflect.Method;

import javax.management.Notification;
import javax.management.ObjectName;

import org.sadun.util.MovedFile;

/**
 * A base class for JMX notifications, containing the original event.
 * 
 *
 * @author Cristiano Sadun
 */
abstract class BaseJMXNotification extends Notification {

    protected BasePollerEvent event;

    /**
     * Open constructor - requires specific initialization since no event is provide
     * @param notificationType
     * @param pollerName
     * @param sqg
     */
    protected BaseJMXNotification(String notificationType, ObjectName pollerName,
            SequenceNumberGenerator sqg, long timestamp) {
        super(notificationType, pollerName, sqg.getNextSequenceNumber(), timestamp);
    }
    
    protected BaseJMXNotification(String notificationType, ObjectName pollerName,
            SequenceNumberGenerator sqg, BasePollerEvent evt) {
        super(notificationType, pollerName, sqg.getNextSequenceNumber(), evt
                .getTime());
        commonInit(evt);
    }

    protected BaseJMXNotification(String notificationType, ObjectName pollerName,
            SequenceNumberGenerator sqg, BasePollerEvent evt, String message) {
        super(notificationType, pollerName, sqg.getNextSequenceNumber(), evt
                .getTime(), message);
        commonInit(evt);
    }

    private void commonInit(BasePollerEvent evt) {
        this.event = evt;
    }

    /**
     * Note: this is null for exception notifications.
     *  
     * @return the event underlying this notification, or null
     */
    protected BasePollerEvent getEvent() {
        return event;
    }
    
    protected static String mkMsg(BasePollerEvent evt, String propertyName) {
        try {
            Method m = evt.getClass().getMethod("get"+propertyName, new Class[0]);
            
            Object obj = m.invoke(evt, new Object[0]);
            
            File file;
            if (obj instanceof File) file=(File)obj;
            else if (obj instanceof MovedFile) file=((MovedFile)obj).getDestinationPath().getCanonicalFile();
            else throw new RuntimeException("Internal error: only File or MovedFile objects are expected by this method");
            try {
                return file.getCanonicalPath();
            } catch(IOException e) {
                return file.getAbsolutePath();
            }
        } catch (Exception e) {
            throw new RuntimeException("Internal error: only events with a get"+propertyName+"() method should be passed to this class. The passed event has class "+evt.getClass(), e);
        }
    }
    
    /**
     * Return the time of the original poller event.
     * @return the time of the original poller event.
     */
    public long getPollerEventTime() { return event.getTime(); }

}