ishostreachablebean.java

snmp zip 包开发snmp协议

// NAME
//      $RCSfile: IsHostReachableBean.java,v $
// DESCRIPTION
//      [given below in javadoc format]
// DELTA
//      $Revision: 1.14 $
// CREATED
//      $Date: 2006/01/26 12:38:59 $
// COPYRIGHT
//      Westhawk Ltd
// TO DO
//

/*
 * Copyright (C) 1998 - 2006 by Westhawk Ltd
 *
 * Permission to use, copy, modify, and distribute this software
 * for any purpose and without fee is hereby granted, provided
 * that the above copyright notices appear in all copies and that
 * both the copyright notice and this permission notice appear in
 * supporting documentation.
 * This software is provided "as is" without express or implied
 * warranty.
 * author <a href="mailto:[e-mail]">Tim Panton</a>
 */

package uk.co.westhawk.snmp.beans;

import uk.co.westhawk.snmp.stack.*;
import uk.co.westhawk.snmp.pdu.*;
import java.awt.*;
import java.util.*;
import java.text.*;
import java.lang.*;
import java.io.*;
import java.beans.*;

/**
 * <p>
 * This bean will determine whether the host+port is up, by sending an
 * UpSincePdu.
 * </p>
 *
 * <p>
 * The properties in the parent classes should be set, before calling
 * the action() method. Via a PropertyChangeEvent the application/applet
 * will be notified.
 * </p>
 *
 * @see SNMPBean#setHost
 * @see SNMPBean#setPort
 * @see SNMPBean#setCommunityName
 * @see SNMPBean#addPropertyChangeListener
 * @see SNMPBean#action
 * @see uk.co.westhawk.snmp.pdu.UpSincePdu
 * 
 * @author <a href="mailto:[e-mail]">Birgit Arkesteijn</a>
 * @version $Revision: 1.14 $ $Date: 2006/01/26 12:38:59 $
 *
 */
public class IsHostReachableBean extends SNMPBean implements Observer 
{
    private static final String     version_id =
        "@(#)$Id: IsHostReachableBean.java,v 1.14 2006/01/26 12:38:59 birgit Exp $ Copyright Westhawk Ltd";

    private UpSincePdu pdu;

    private Date upSince = null;
    private boolean isReachable = false;
    
    private SimpleDateFormat dateFormat;


/**
 * The default constructor.
 */
public IsHostReachableBean() 
{
    dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss zzz");
    dateFormat.setTimeZone(TimeZone.getTimeZone("GMT"));
}

/**
 * The constructor that will set the host and the port no.
 *
 * @param h the hostname
 * @param p the port no
 * @see SNMPBean#setHost
 * @see SNMPBean#setPort
 */
public IsHostReachableBean(String h, int p) 
{
    this(h, p, null);
}

/**
 * The constructor that will set the host, the port no and the local
 * bind address.
 *
 * @param h the hostname
 * @param p the port no
 * @param b the local bind address
 * @see SNMPBean#setHost
 * @see SNMPBean#setPort
 * @see SNMPBean#setBindAddress
 *
 * @since 4_14
 */
public IsHostReachableBean(String h, int p, String b) 
{
    this();
    setHost(h);
    setPort(p);
    setBindAddress(b);
}

/**
 * Returns the date when the host went up. This might be null is no
 * answer is received yet.
 * @return the date 
 *
 * @see SNMPBean#getMessage()
 * @see #isReachable()
 */
public Date getUpSinceDate()
{
    return upSince;
}

/**
 * Answer is set according to the received SNMP response.
 * @see #getUpSinceDate()
 */
protected void setUpSinceDate(Date d)
{
    upSince = d;
}

/**
 * Indicates whether the host + port is reachable.
 * The host + port is reachable if a valid response is received from a 
 * UpSincePdu request.
 * @return is the host + port + community name valid
 *
 * @see SNMPBean#getMessage()
 * @see #getUpSinceDate()
 */
public boolean isReachable()
{
    return isReachable;
}

/**
 * The reachable property is set according to the succes of making 
 * a connection and the response of the SNMP request.
 * This method will fire a Property Change Event.
 *
 * @see #isReachable()
 * @see SNMPBean#addPropertyChangeListener
 */
protected void setReachable(boolean b)
{
    boolean old;
    old = isReachable;
    isReachable = b;

    firePropertyChange("Reachable", new Boolean (old), 
          new Boolean (isReachable));
}


/**
 * This method performs the request and wait for it. It is not
 * recommended to use the waitForSelf option, preferred is the action()
 * method. 
 * Use it if it is really necessary to wait. 
 *
 * @see SnmpContext
 * @see #action()
 * @see Pdu#waitForSelf()
 */
public void waitForSelfAction()
throws PduException, java.io.IOException
{
    action(true);
}

/**
 * This method actually performs the request. All properties should be
 * set before this method is called.
 *
 * This will create a new SnmpContext and send a UpSincePdu SNMP
 * request.
 * If the connection fails, the reachable property will be set to false.
 *
 * @see SnmpContext
 */
public void action()
throws PduException, java.io.IOException
{
    action(false);
}

protected void action(boolean wait) 
throws PduException, java.io.IOException
{
    if (host != null
             &&
        host.length() > 0
             &&
        port > 0)
    {
        try
        {
            if (context != null)
            {
                context.destroy();
            }
            context = new SnmpContext(host, port, bindAddr, socketType);
            context.setCommunity(community);
            setMessage("Connection to host " + host 
                + " is made succesfully");

            if (wait == true)
            {
                pdu = new UpSincePdu(context, null);
                if (pdu.waitForSelf())
                {
                    this.update((Observable) pdu, (Object) null);
                }
                else
                {
                    setMessage("No SNMP Response from " + host);
                }
            }
            else
            {
                pdu = new UpSincePdu(context, this);
            }
        }
        catch (IOException exc)
        {
            setMessage("IOException: " + exc.getMessage());
            setReachable(false);
        }
        catch (RuntimeException exc)
        {
            setMessage("RuntimeException: " + exc.getMessage());
            setReachable(false);
        }
    }
}

/**
 * The update method according to the Observer interface, it will be
 * called when the Pdu response is received.
 * If there is no error it means that the host is reachable. If it is
 * not reachable the message will contain the type of error, if it is
 * reachable the message will say since when the host is up.
 */
public void update(Observable obs, Object ov)
{
    pdu = (UpSincePdu) obs;

    if (pdu.getErrorStatus() == AsnObject.SNMP_ERR_NOERROR)
    {
        setUpSinceDate(pdu.getDate());
        setMessage("Host " + host + " is up since " 
              + dateFormat.format(getUpSinceDate()));
        setReachable(true);
    }
    else
    {
        setUpSinceDate(null);
        setMessage("SNMP Response: " + pdu.getErrorStatusString());
        setReachable(false);
    }
}


/**
 * Destroys the context.
 * @since 4_14
 */
public void freeResources()
{
    if (context != null)
    {
        context.destroy();
        context = null;
    }
}


}