peerconnection.java

jxme的一些相关程序,主要是手机上程序开发以及手机和计算机通信的一些程序资料,程序编译需要Ant支持

/*
 *
 * $Id: PeerConnection.java,v 1.5 2002/06/18 20:46:01 hamada Exp $
 *
 * Copyright (c) 2001 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:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions 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.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *       Sun Microsystems, Inc. for Project JXTA."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Sun", "Sun Microsystems, Inc.", "JXTA" and "Project JXTA"
 *    must not be used to endorse or promote products derived from this
 *    software without prior written permission. For written
 *    permission, please contact Project JXTA at http://www.jxta.org.
 *
 * 5. Products derived from this software may not be called "JXTA",
 *    nor may "JXTA" appear in their name, without prior written
 *    permission of Sun.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL SUN MICROSYSTEMS OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of Project JXTA.  For more
 * information on Project JXTA, please see
 * <http://www.jxta.org/>.
 *
 * This license is based on the BSD license adopted by the Apache Foundation.
*/

package net.jxta.impl.rendezvous;

import java.net.*;
import java.util.*;

import org.apache.log4j.Category; 
import org.apache.log4j.Priority;

import net.jxta.id.*;
import net.jxta.peer.*;
import net.jxta.protocol.*;
import net.jxta.document.*;
import net.jxta.rendezvous.*;
import net.jxta.endpoint.*;
import net.jxta.discovery.*;
import net.jxta.peergroup.*;
import net.jxta.impl.util.*;
import net.jxta.impl.endpoint.EndpointReceiveQueue;

/**
 * Class used to manage a connection with a client or a rendezvous peer.
 **/

public class PeerConnection implements Runnable {

	private final static Category LOG = Category.getInstance(PeerConnection.class.getName());
	public  final static int MaxNbOfMessages = 40;

	private String  peer = null;
	private String  peerName = null;
	private long    lease = 0;
	private boolean connected = false;
	private EndpointService endpoint = null;
	private DiscoveryService discovery = null;
	private EndpointReceiveQueue queue = null;
	private Thread thread = null;

	/**
	 *Constructor for the PeerConnection object
	 *
	 * WARNING: this constructor can be used for simply testing against
	 * existing connection. This constructor must NOT allocate any resources.
	 */
	public PeerConnection(PeerGroup group, String p, long l) {

		this.peer = p;
		this.endpoint = group.getEndpointService();
		this.discovery = group.getDiscoveryService();
		this.connected = true;

		if ((System.currentTimeMillis() + l) < 0) {
			// This is the case when the lease is infinite
			this.lease = l;
		} else {
			this.lease = System.currentTimeMillis() + l;
		}

	}

	// Try to connect. This operation is idempotent.
	public synchronized void connect () {

		// We assume that we can be connected.
		connected = true;

		if (queue == null) {
			// There is new queue. Create one.
			queue = new EndpointReceiveQueue();
			queue.setMaxNbOfMessages (MaxNbOfMessages);
		}

		// Start the background thread.
		if (thread != null) {
			// Nothing to do
			return;
		}
		thread = new Thread (this, "RDV Connection to " + getPeerName());
		thread.start();
		Thread.currentThread().yield();
	}

	private synchronized void setThreadName () {

		if (thread != null) {
			try {
				thread.setName ("RDV Connection [queue = " + queue.getNbOfQueuedMessages() + " ] to " + getPeerName());
			} catch (Exception ez1) {
				if (LOG.isEnabledFor(Priority.ERROR)) LOG.error("Cannot change thread name", ez1);
			}
		}
	}

	// Get the peer name. If the symobolic name is available, use it,
	// otherwise returns the peer id.
	public synchronized String getPeerName() {

		// If we already have a name used it.
		if (peerName != null) {
			return peerName;
		}
		// Try to see if we have a peer advertisement for this peer.
		// This is very likely.
		try {
			Enumeration enum = discovery.getLocalAdvertisements (DiscoveryService.PEER,
			                   "PID",
			                   peer);
			if ((enum != null) && (enum.hasMoreElements())) {
				PeerAdvertisement adv = (PeerAdvertisement) enum.nextElement();
				peerName = adv.getName();
			}
		} catch (Exception ez1) {
			peerName = null;
			return peer;
		}
		return peerName;
	}


	// Set the lease.
	public synchronized void setLease (long lease) {
		this.lease = lease;
	}

	// Get the lease
	public synchronized long getLease() {
		return lease;
	}

	// Test if the connection is up
	public synchronized boolean isConnected() {
		return connected;
	}

	// Set the peer id
	public synchronized void setPeer (String peer) {
		this.peer = peer;
	}

	// Get the peer id
	public synchronized String getPeer() {
		return peer;
	}


	// get an EndpointMessenger to the remote peer.
	private EndpointMessenger getMessenger(String pName, String pParam) {

		EndpointMessenger tmpMessenger = null;

		try {
			tmpMessenger = endpoint.getMessenger(mkAddress(peer,
			                                     pName,
			                                     pParam));
			return tmpMessenger;
		} catch (Exception e) {
			return null;
		}
	}


	// doSendMessage actually sends the message to the remote peer.
	private void doSendMessage (Message msg) {

		if (!isConnected()) {
			// This connection is closed. Do nothing.
			return;
		}

		// Recover the service name and parameter from the message.
		EndpointAddress dstAddress = msg.getDestinationAddress();
		String pName = dstAddress.getServiceName();
		String pParam = dstAddress.getServiceParameter();

		EndpointMessenger messenger = getMessenger (pName, pParam);
		if (messenger == null) {
			// We cannot get a Messenger. Connection is broken.
			notifyFailure();
			return;
		}

		try {
			messenger.sendMessage (msg);
		} catch (Exception e) {
			// Connection is broken.
			notifyFailure();
		}
	}


	// Public method that sends messages to the remote peer.
	// Only queue the message and let the background thread actually sends the message.

	public void sendMessage (Message msg, String pName, String pParam) {

		if (!isConnected()) {
			// No connection. The message is dropped.
			return;
		}

		// Set the destination of the message, so the background thread can
		// recover pParam and pName.
		EndpointAddress dstAddress = msg.getDestinationAddress();
		if (dstAddress != null) {
			dstAddress.setServiceName (pName);
			dstAddress.setServiceParameter (pParam);
		} else {
			dstAddress = mkAddress (peer, pName, pParam);
		}
		msg.setDestinationAddress (dstAddress);

		// Queue the message.
		synchronized (this) {
			queue.push (msg);
			setThreadName();
		}
	}

	/**
	 * Build an EndpointAddress the EndpointRouter can use.
	 */
	private EndpointAddress mkAddress(String destPeer) {
		try {
			PeerID asID = (PeerID) IDFactory.fromURL(IDFactory.jxtaURL(destPeer));
			String asString = "jxta://"
			                  + asID.getUniqueValue().toString();
			EndpointAddress addr = endpoint.newEndpointAddress(asString);
			return addr;
		} catch (Exception e) {
			if (LOG.isEnabledFor(Priority.WARN)) LOG.warn("Invalid peerID string " + destPeer);
			return null;
		}
	}

	/**
	 * Build an EndpointAddress the EndpointRouter can use.
	 */
	private EndpointAddress mkAddress(String destPeer,
	                                  String serv,
	                                  String parm) {

		EndpointAddress addr = mkAddress(destPeer);
		addr.setServiceName(serv);
		addr.setServiceParameter(parm);
		return addr;
	}

	public boolean equals(Object obj) {
		if (peer.equals(((PeerConnection) obj).peer)) {
			return true;
		} else {
			return false;
		}
	}

	// This is the background Thread. While the connection is active, takes
	// messages from the queue and send it.
	public void run() {

		Message msg = null;
		while (true) {

			if (!isConnected()) {
				// This connection is closed. Exit.
				close();
				return;
			}
			try {
				// Wait for messages to be sent.
				msg = queue.waitForMessage();
				setThreadName();
			} catch (InterruptedException e) {
				if (!isConnected()) {
					// The connection is just being close. This Thread must exit.
					close();
					return;
				} else {
					// This is a failure.
					notifyFailure();
					continue;
				}
			}
			// Send the message.
			doSendMessage (msg);
		}
	}

	// We just close the connection and set the connected status to false.
	private synchronized void notifyFailure() {
		close();
		connected = false;
	}


	// Close the connection. This operation must be idempotent.
	public synchronized void close() {

		connected = false;
		if (queue != null) {
			queue.close();
			queue = null;
		}
		if (thread != null) {
			try {
				thread.interrupt();
				thread = null;
			} catch (Exception ez1) {
				if (LOG.isEnabledFor(Priority.WARN)) LOG.warn("Cannot interrupt RDV thread for " + getPeerName(), ez1);
			}
		}
	}

	// Just in case the code that allocated an instance of this object forgot to do "close".
	public void finalize() {
		close();
	}

}