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The JXTA Shell is a sample application that demonstrates key concepts
of JXTA JXSE. The JXTA Shell enables users to interact with the JXTA
platform through a command-line interpreter. Much like the UNIX® shell,
the JXTA Shell is useful for accessing and managing core platform objects
(peers, groups, pipes), debugging communications problems, checking the
status of peers and/or peer groups, and communicating with other JXTA
services and applications. As in UNIX®, the JXTA shell allows users to
"pipe" shell commands together connecting commands "on-the-fly." Pipes
in Project JXTA are useful for collecting information at one peer and
perhaps processing the command at another.
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/*
* 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
*
The different queues are stored in a hashtable, where the key is
*/
public class HistoryQueue {
/**
* The maximum number of commands
*/
protected static final int MAX_HISTORY = 100;
/**
* The vector that holds the commands
*/
private List queue;
/**
* The index at for the next commend to retrieve
*/
private int nextCommand = -1;
/**
* Array containing the commands that are not added to the command list
*/
private final String exclude[];
/**
* Create a new history queue
*/
public HistoryQueue() {
this(new String[0]);
}
/**
* Create a new history queue
*
* @param exclude the commands to not add to the queue (that are the
* usually Cursor up and down events )
*/
public HistoryQueue(String exclude[]) {
queue = new ArrayList(MAX_HISTORY);
nextCommand = -1;
this.exclude = exclude;
}
@Override
public String toString() {
return "History queue of " + queue.size();
}
/**
* Adds a new command to the queue.
*
* If the queue has already reached MAX_HISTORY, the element at
* index 0 is discarded.
*
* @param cmd the command to add
*/
public synchronized void addCommand(String cmd) {
cmd = cmd.trim();
// no empty commands
if (0 == cmd.length())
return;
// none of the excludes
for (String anExclude : exclude) {
if (anExclude.equals(cmd))
return;
}
// remove extra commands
while (queue.size() >= MAX_HISTORY) {
queue.remove(0);
}
String last = null;
if (queue.size() > 0) {
last = queue.get(queue.size() - 1);
}
// add if not the same as the last command.
if (!cmd.equals(last)) {
queue.add(cmd);
}
nextCommand = queue.size();
}
/**
* Removes the last command added to the queue
*/
public synchronized void removeLastCommand() {
if (queue.size() > 0) {
queue.remove(queue.size() - 1);
nextCommand = queue.size();
}
}
/**
* Returns the command immediately preceeding the previous command
*/
public String getNextCommand() {
nextCommand--;
if (nextCommand < 0) nextCommand = -1;
return getCommand(nextCommand);
}
/**
* Returns the command immediately succedding the previous command
* THIS needs help !!
*/
public String getPreviousCommand() {
nextCommand++;
if (nextCommand > queue.size()) nextCommand = queue.size();
return getCommand(nextCommand);
}
/**
* Gets the command at index, if there is an element at index.
* Otherwise, an empty string is returned
*
* @return the command at index, if there is an element at index
* or an empty string, if index is out of range
*/
public String getCommand(int index) {
return (index < 0 || index >= queue.size()) ? "" : queue.get(index);
}
/**
* Prints the available commands to a String.
* If no commands are available, we return and empty string
*/
public String printHistory() {
StringBuilder buffer = new StringBuilder();
int k;
int i;
int max = queue.size();
int length = String.valueOf(MAX_HISTORY).length();
String number;
for (i = 0; i < max; i++) {
number = String.valueOf(i);
k = 0;
while ((k++ + number.length()) != length)
buffer.append(" ");
buffer.append(number).append(" ");
buffer.append(queue.get(i));
buffer.append("\n");
}
return buffer.toString();
}
}