shellinputpipe.java

有关java 的p2p应用,是一般很好的教程,有兴趣的朋友应该好好阅读一下

/*
 *  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.
 *
 *  $Id: ShellInputPipe.java,v 1.24 2006/06/14 16:37:12 bondolo Exp $
 */
package net.jxta.impl.shell;

import java.io.InterruptedIOException;

import java.util.logging.Logger;
import java.util.logging.Level;

import net.jxta.endpoint.Message;
import net.jxta.endpoint.MessageElement;
import net.jxta.endpoint.StringMessageElement;
import net.jxta.peergroup.PeerGroup;
import net.jxta.pipe.InputPipe;
import net.jxta.id.ID;
import net.jxta.protocol.PipeAdvertisement;
import net.jxta.pipe.PipeMsgEvent;
import net.jxta.pipe.PipeMsgListener;

import net.jxta.impl.util.UnbiasedQueue;

/**
 *  This class implements the default JXTA Shell InputPipe. Strings entered at
 *  the keyboard are received by the Shell like if they were messages received
 *  from a regular InputPipe.
 */
public class ShellInputPipe implements Runnable, InputPipe {
    
    /**
     *  Log4J Logger
     */
    private static final transient java.util.logging.Logger LOG = java.util.logging.Logger.getLogger(ShellInputPipe.class.getName());;
    
    /**
     *  if we have been closed then no more new messages will be queued. Msgs
     *  already in the queue can be retrieved.
     */
    private volatile boolean closed = false;
    
    
    private ShellConsole cons;
    
     private PipeMsgListener listener = null;
    
    /**
     *  contains the messages.
     */
    private UnbiasedQueue queue = null;
    
    private Thread thread = null;
        
    /**
     *  Constructor for the ShellInputPipe object
     *
     *@param  group
     *@param  cons
     */
    public ShellInputPipe( PeerGroup group, ShellConsole cons ) {
        this(group, cons, null);
    }
    
    
    /**
     *  Constructor for the ShellInputPipe object
     *
     *@param  group
     *@param  cons
     *@param  listener
     */
    public ShellInputPipe( PeerGroup group, ShellConsole cons, PipeMsgListener listener ) {
        
        this.cons = cons;
        this.listener = listener;
        if (listener == null) {
            queue = UnbiasedQueue.synchronizedQueue(new UnbiasedQueue());
        }
        thread = new Thread(group.getHomeThreadGroup(), this, "ShellInputPipe-" + cons.getConsoleName());
        thread.setDaemon(true);
        thread.start();
    }
    
    
    /**
     *  {@inheritDoc}
     **/
    public Message waitForMessage() throws InterruptedException {
        return poll( 0 );
    }
    
    /**
     *  {@inheritDoc}
     **/
    public Message poll(int time) throws InterruptedException {
        
        Message msg = null;
        if (listener == null) {
            msg = (Message) queue.pop(time);
        }
        return msg;
    }
    
    /**
     *  {@inheritDoc}
     **/
    public synchronized void close() {
        // Close the queue
        closed = true;
        
        if (queue != null) {
            queue.close();
        }
        
        Thread copyThread = thread;
        if (copyThread != null) {
            copyThread.interrupt();
        }
    }
       
    /**
     *  {@inheritDoc}
     *
     *  <p/>Not implemented.
     **/
    public PipeAdvertisement getAdvertisement() {
        throw new UnsupportedOperationException( "Not supported by ShellInputPipe" );
    }
    
    
    /**
     *  {@inheritDoc}
     *
     *  <p/>Not implemented.
     **/
    public String getName() {
        throw new UnsupportedOperationException( "Not supported by ShellInputPipe" );
    }
    
    
    /**
     *  {@inheritDoc}
     **/
    public ID getPipeID() {
        throw new UnsupportedOperationException( "Not supported by ShellInputPipe" );
    }
    
    /**
     *  {@inheritDoc}
     **/
    public String getType() {
        throw new UnsupportedOperationException( "Not supported by ShellInputPipe" );
    }
    
    /**
     *  {@inheritDoc}
     **/
    public void run() {
        
        try {
            while (!closed) {
                String line;

                try {
                    line = cons.read();
                }
                catch (InterruptedIOException woken) {
                    Thread.interrupted();
                    continue;
                }
                if (line == null) {
                    break;
                }
                // Create a message off this string.
                Message msg = new Message();
                MessageElement elem = new StringMessageElement("ShellInputPipe",
                                                               line, null);

                msg.addMessageElement(elem);
                if (null != listener) {
                    PipeMsgEvent event = new PipeMsgEvent(this, msg, null);

                    try {
                        listener.pipeMsgEvent(event);
                    }
                    catch (Throwable ignored) {
                        if (LOG.isLoggable(java.util.logging.Level.SEVERE)) {
                            LOG.log(java.util.logging.Level.SEVERE,
                                    "Uncaught Throwable in listener (" +
                                    listener.getClass().getName() + ")", ignored);
                        }
                    }
                }
                else {
                    boolean pushed = false;

                    while (!pushed && !queue.isClosed()) {
                        try {
                            pushed = queue.push(msg, 100L);
                        }
                        catch (InterruptedException woken) {
                            Thread.interrupted();
                        }
                    }
                }
            }
        }
        catch (Throwable all) {
            if (LOG.isLoggable(java.util.logging.Level.SEVERE)) {
                LOG.log(java.util.logging.Level.SEVERE,
                        "Uncaught Throwable in thread :" +
                        Thread.currentThread().getName(), all);
            }
        }
        finally {
            thread = null;
        }
    }
}