/*****************************************************************
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
****************************************************************/
package org.apache.cayenne.project.upgrade;
import org.apache.cayenne.ConfigurationException;
import org.apache.cayenne.configuration.DataChannelDescriptor;
import org.apache.cayenne.map.DataMap;
import org.apache.cayenne.map.EntityResolver;
import org.apache.cayenne.resource.Resource;
import org.apache.cayenne.util.Util;
import org.xml.sax.Attributes;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.DefaultHandler;
import java.io.InputStream;
import java.net.URL;
/**
* A common superclass of UpgradeHandlers.
*
* @since 3.1
*/
// there's no guarantee this will survive the further version upgrades, but for
// now all
// the code here seems like version-agnostic
public abstract class BaseUpgradeHandler implements UpgradeHandler {
static final String UNKNOWN_VERSION = "0";
static final String MIN_SUPPORTED_VERSION = "3.0.0.1";
protected Resource projectSource;
protected UpgradeMetaData metaData;
public BaseUpgradeHandler(Resource projectSource) {
if (projectSource == null) {
throw new NullPointerException("Null project source");
}
this.projectSource = projectSource;
}
/**
* Creates a single common EntityResolver for all project DataMaps, setting
* it as a namespace for all of them. This is needed for resolving cross-map
* relationships.
*/
protected void attachToNamespace(DataChannelDescriptor channelDescriptor) {
EntityResolver entityResolver = new EntityResolver(channelDescriptor.getDataMaps());
for (DataMap map : entityResolver.getDataMaps()) {
map.setNamespace(entityResolver);
}
}
@Override
public Resource getProjectSource() {
return projectSource;
}
@Override
public UpgradeMetaData getUpgradeMetaData() {
// no attempts at thread-safety... shouldn't be needed for upgrades
if (metaData == null) {
metaData = loadMetaData();
}
return metaData;
}
@Override
public Resource performUpgrade() throws ConfigurationException {
UpgradeMetaData metaData = getUpgradeMetaData();
switch (metaData.getUpgradeType()) {
case DOWNGRADE_NEEDED:
throw new ConfigurationException("Downgrade can not be performed");
case INTERMEDIATE_UPGRADE_NEEDED:
throw new ConfigurationException("Upgrade can not be performed - intermediate version upgrade needed");
case UPGRADE_NEEDED:
return doPerformUpgrade(metaData);
default:
return getProjectSource();
}
}
/**
* Does the actual project upgrade, assuming the caller already verified
* that the upgrade is possible.
*
* @param metaData
* object describing the type of upgrade
*/
protected abstract Resource doPerformUpgrade(UpgradeMetaData metaData) throws ConfigurationException;
protected abstract String getToVersion();
/**
* Creates a metadata object describing the type of upgrade needed.
*/
protected UpgradeMetaData loadMetaData() {
String version = loadProjectVersion();
UpgradeMetaData metadata = new UpgradeMetaData();
metadata.setSupportedVersion(getToVersion());
metadata.setProjectVersion(version);
int c1 = compareVersions(version, MIN_SUPPORTED_VERSION);
int c2 = compareVersions(getToVersion(), version);
if (c1 < 0) {
metadata.setIntermediateUpgradeVersion(MIN_SUPPORTED_VERSION);
metadata.setUpgradeType(UpgradeType.INTERMEDIATE_UPGRADE_NEEDED);
} else if (c2 < 0) {
metadata.setUpgradeType(UpgradeType.DOWNGRADE_NEEDED);
} else if (c2 == 0) {
metadata.setUpgradeType(UpgradeType.UPGRADE_NOT_NEEDED);
} else {
metadata.setUpgradeType(UpgradeType.UPGRADE_NEEDED);
}
return metadata;
}
/**
* A default method for quick extraction of the project version from an XML
* file.
*/
protected String loadProjectVersion() {
RootTagHandler rootHandler = new RootTagHandler();
URL url = projectSource.getURL();
try (InputStream in = url.openStream();) {
XMLReader parser = Util.createXmlReader();
parser.setContentHandler(rootHandler);
parser.setErrorHandler(rootHandler);
parser.parse(new InputSource(in));
} catch (SAXException e) {
// expected ... handler will terminate as soon as it finds a root
// tag.
} catch (Exception e) {
throw new ConfigurationException("Error reading configuration from %s", e, url);
}
return rootHandler.projectVersion != null ? rootHandler.projectVersion : UNKNOWN_VERSION;
}
/**
* Compares two String versions.
*/
protected int compareVersions(String v1, String v2) {
if (v1.equals(v2)) {
return 0;
}
double v1Double = decodeVersion(v1);
double v2Double = decodeVersion(v2);
return v1Double < v2Double ? -1 : 1;
}
protected double decodeVersion(String version) {
if (version == null || version.trim().length() == 0) {
return 0;
}
// leave the first dot, and treat remaining as a fraction
// remove all non digit chars
StringBuilder buffer = new StringBuilder(version.length());
boolean dotProcessed = false;
for (int i = 0; i < version.length(); i++) {
char nextChar = version.charAt(i);
if (nextChar == '.' && !dotProcessed) {
dotProcessed = true;
buffer.append('.');
} else if (Character.isDigit(nextChar)) {
buffer.append(nextChar);
}
}
return Double.parseDouble(buffer.toString());
}
class RootTagHandler extends DefaultHandler {
private String projectVersion;
@Override
public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
this.projectVersion = attributes.getValue("", "project-version");
// bail right away - we are not interested in reading this to the
// end
throw new SAXException("finished");
}
}
}