// BlogBridge -- RSS feed reader, manager, and web based service
// Copyright (C) 2002-2006 by R. Pito Salas
//
// This program is free software; you can redistribute it and/or modify it under
// the terms of the GNU General Public License as published by the Free Software Foundation;
// either version 2 of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
// without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
// See the GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License along with this program;
// if not, write to the Free Software Foundation, Inc., 59 Temple Place,
// Suite 330, Boston, MA 02111-1307 USA
//
// Contact: R. Pito Salas
// mailto:pitosalas@users.sourceforge.net
// More information: about BlogBridge
// http://www.blogbridge.com
// http://sourceforge.net/projects/blogbridge
//
// $Id: Checker.java,v 1.6 2006/05/29 12:48:31 spyromus Exp $
//
package com.salas.bb.updates;
import com.salas.bb.service.ServerService;
import com.salas.bb.service.ServerServiceException;
import com.salas.bb.utils.StringUtils;
import com.salas.bb.utils.i18n.Strings;
import com.salas.bbutilities.opml.utils.EmptyEntityResolver;
import org.jdom.Document;
import org.jdom.JDOMException;
import org.jdom.Element;
import org.jdom.input.SAXBuilder;
import java.io.IOException;
import java.io.StringReader;
import java.util.logging.Logger;
import java.util.logging.Level;
import java.util.Map;
import java.util.List;
import java.util.HashMap;
/**
* Checks for new versions available for download. Makes XML-RPC call to the service
* and analyzes the response.
*/
public final class Checker
{
private static final Logger LOG = Logger.getLogger(Checker.class.getName());
/**
* Checks server for new version.
*
* @param currentVersion current application version to tell service.
*
* @return result object or <code>NULL</code> if no updates available.
*
* @throws IOException when I/O error happens.
*/
public CheckResult checkForUpdates(String currentVersion)
throws IOException
{
CheckResult result = null;
try
{
String response = queryServiceForUpdates(currentVersion);
result = convertResponseToResult(response);
} catch (JDOMException e)
{
LOG.log(Level.SEVERE, Strings.error("updates.failed.to.parse.response"), e);
throw new IOException(Strings.error("updates.failed.to.parse.response"));
} catch (ServerServiceException e)
{
LOG.log(Level.SEVERE, Strings.error("updates.failed.to.query.service.for.updates"), e);
throw new IOException(Strings.error("updates.failed.to.query.service.for.updates"));
}
return result;
}
/**
* Queries some service for updates availability.
*
* @param currentVersion currently installed version.
*
* @return response of the service in XML format.
*/
private String queryServiceForUpdates(String currentVersion)
throws ServerServiceException
{
return ServerService.checkForUpdates(currentVersion);
}
/**
* Converts response of the service (in XML format) into valid result object.
*
* @param aResponse response.
*
* @return result object or <code>NULL</code> if no updates available.
*
* @throws IOException when I/O exception happens.
* @throws JDOMException when response is unparsable XML.
*/
private CheckResult convertResponseToResult(String aResponse)
throws IOException, JDOMException
{
CheckResult result = null;
if (!StringUtils.isEmpty(aResponse))
{
Document doc = parse(aResponse);
result = convertDocumentToResult(doc);
}
return result;
}
/**
* Converts parsed XML document into result object.
*
* @param aDocument document.
*
* @return result object.
*/
private CheckResult convertDocumentToResult(Document aDocument)
{
Element root = aDocument.getRootElement();
String recentVersion = root.getChildTextTrim("version");
long releaseTime = Long.parseLong(root.getChildTextTrim("releaseTime"));
VersionChange[] changes = changesToList(root.getChild("changes"));
Map locations = locationsToMap(root.getChild("locations"));
return new CheckResult(recentVersion, releaseTime, changes, locations);
}
/**
* Converts list of locations to map.
*
* @param aLocations locations element to lookup locations at.
*
* @return populated map (type- to path).
*/
private Map locationsToMap(Element aLocations)
{
Map locations;
if (aLocations != null)
{
List locationElements = aLocations.getChildren("location");
locations = new HashMap(locationElements.size());
for (int i = 0; i < locationElements.size(); i++)
{
Element locationElement = (Element)locationElements.get(i);
String type = locationElement.getAttributeValue("type");
String path = locationElement.getAttributeValue("path");
String description = locationElement.getAttributeValue("description");
String sizeS = locationElement.getAttributeValue("size");
long size = Long.parseLong(sizeS);
locations.put(type, new Location(type, description, path, size));
}
} else locations = new HashMap();
return locations;
}
/**
* Converts list of "change" elements under "changes" element to array
* of version change objects.
*
* @param aChanges changes element.
*
* @return array of changes.
*/
private VersionChange[] changesToList(Element aChanges)
{
VersionChange[] changes;
if (aChanges != null)
{
List changesElements = aChanges.getChildren("change");
int count = changesElements.size();
changes = new VersionChange[count];
for (int i = 0; i < count; i++)
{
Element change = (Element)changesElements.get(i);
changes[i] = changeToItem(change);
}
} else changes = new VersionChange[0];
return changes;
}
/**
* Converts change element to version change object.
*
* @param aChange change element.
*
* @return version change object.
*/
private VersionChange changeToItem(Element aChange)
{
int type = Integer.parseInt(aChange.getAttributeValue("type"));
String details = aChange.getTextTrim();
return new VersionChange(type, details);
}
/**
* Parses XML response into document.
*
* @param aResponse response to parse.
*
* @return document.
*
* @throws IOException when I/O exception happens.
* @throws JDOMException when response is unparsable XML.
*/
private Document parse(String aResponse)
throws IOException, JDOMException
{
SAXBuilder builder = new SAXBuilder(false);
builder.setEntityResolver(EmptyEntityResolver.INSTANCE);
return builder.build(new StringReader(aResponse));
}
}