com.ibm.jbatch.container.services.impl.JSEBatchArtifactFactoryImpl Maven / Gradle / Ivy
/*
* Copyright 2012 International Business Machines Corp.
*
* See the NOTICE file distributed with this work for additional information
* regarding copyright ownership. Licensed 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 com.ibm.jbatch.container.services.impl;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.xml.namespace.QName;
import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLStreamConstants;
import javax.xml.stream.XMLStreamReader;
import com.ibm.jbatch.container.exception.BatchContainerRuntimeException;
import com.ibm.jbatch.container.exception.BatchContainerServiceException;
import com.ibm.jbatch.spi.services.IBatchArtifactFactory;
import com.ibm.jbatch.spi.services.IBatchConfig;
public class JSEBatchArtifactFactoryImpl implements IBatchArtifactFactory, XMLStreamConstants {
private final static Logger logger = Logger.getLogger(JSEBatchArtifactFactoryImpl.class.getName());
private final static String CLASSNAME = JSEBatchArtifactFactoryImpl.class.getName();
// TODO - surface constants
private final static String BATCH_XML = "META-INF/batch.xml";
private final static QName BATCH_ROOT_ELEM = new QName("http://xmlns.jcp.org/xml/ns/javaee", "batch-artifacts");
// TODO - synchronize appropriately once we learn more about usage
private boolean loaded = false;
private volatile ArtifactMap artifactMap = null;
// Uses TCCL
@Override
public Object load(String batchId) {
String methodName = "load";
if (logger.isLoggable(Level.FINER)) {
logger.entering(CLASSNAME, methodName, "Loading batch artifact id = " + batchId);
}
ClassLoader tccl = Thread.currentThread().getContextClassLoader();
if (logger.isLoggable(Level.FINE)) {
logger.fine("TCCL = " + tccl);
}
initArtifactMapFromClassLoader(tccl);
Object loadedArtifact = artifactMap.getArtifactById(batchId);
if (loadedArtifact == null) {
throw new IllegalArgumentException("Could not load any artifacts with batch id=" + batchId);
}
if (logger.isLoggable(Level.FINER)) {
logger.exiting(CLASSNAME, methodName, "For batch artifact id = " + batchId + ", loaded artifact instance: " +
loadedArtifact + " of type: " + loadedArtifact.getClass().getCanonicalName());
}
return loadedArtifact;
}
private void initArtifactMapFromClassLoader(ClassLoader loader) {
/*
* Following pattern in:
* http://en.wikipedia.org/wiki/Double-checked_locking
*/
ArtifactMap tempMap = artifactMap;
if (tempMap == null) {
synchronized(this) {
tempMap = artifactMap;
if (tempMap == null) {
tempMap = new ArtifactMap();
InputStream is = getBatchXMLStreamFromClassLoader(loader);
artifactMap = populateArtifactMapFromStream(tempMap, is);
}
}
}
}
protected InputStream getBatchXMLStreamFromClassLoader(ClassLoader loader) {
InputStream is = loader.getResourceAsStream(BATCH_XML);
if (is == null) {
throw new IllegalStateException("Unable to load batch.xml");
}
return is;
}
/*
* Non-validating (e.g. that the artifact type is correct) load
*
* TODO - add some logging to the parsing
*/
protected ArtifactMap populateArtifactMapFromStream(ArtifactMap tempMap, InputStream is) {
XMLInputFactory xmlInputFactory = XMLInputFactory.newInstance();
try {
XMLStreamReader xmlStreamReader = xmlInputFactory.createXMLStreamReader(is);
if (logger.isLoggable(Level.FINEST)) {
logger.finest("Loaded XMLStreamReader = " + xmlStreamReader);
}
boolean processedRoot = false;
// We are going to take advantage of the simplified structure of a
// line
// E.g.:
//
//
// ..
//
//
// and have much simpler logic than general-purpose parsing would
// require.
while (xmlStreamReader.hasNext()) {
int event = xmlStreamReader.next();
// Until we reach end of document
if (event == END_DOCUMENT) {
break;
}
// At this point we have either:
// A) just passed START_DOCUMENT, and are at START_ELEMENT for the root,
// , or
// B) we have just passed END_ELEMENT for one of the artifacts which is a child of
// .
//
// Only handle START_ELEMENT now so we can skip whitespace CHARACTERS events.
//
if (event == START_ELEMENT) {
if (!processedRoot) {
QName rootQName = xmlStreamReader.getName();
if (!rootQName.equals(BATCH_ROOT_ELEM)) {
throw new IllegalStateException("Expecting document with root element QName: " + BATCH_ROOT_ELEM
+ ", but found root element with QName: " + rootQName);
} else {
processedRoot = true;
}
} else {
// Should only need localName
String annotationShortName = xmlStreamReader.getLocalName();
String id = xmlStreamReader.getAttributeValue(null, "id");
String className = xmlStreamReader.getAttributeValue(null, "class");
tempMap.addEntry(annotationShortName, id, className);
// Ignore anything else (text/whitespace) within this
// element
while (event != END_ELEMENT) {
event = xmlStreamReader.next();
}
}
}
}
xmlStreamReader.close();
is.close();
return tempMap;
} catch (Exception e) {
throw new RuntimeException(e);
}
}
private class ArtifactMap {
private Map idToArtifactClassMap = new HashMap();
// Maps to a list of types not a single type since there's no reason a single artifact couldn't be annotated
// with >1 batch artifact annotation type.
private Map> idToArtifactTypeListMap = new HashMap>();
/*
* Init already synchronized, so no need to synch further
*/
private void addEntry(String batchTypeName, String id, String className) {
try {
if (!idToArtifactClassMap.containsKey(id)) {
Class artifactClass = Thread.currentThread().getContextClassLoader().loadClass(className);
idToArtifactClassMap.put(id, artifactClass);
List typeList = new ArrayList();
typeList.add(batchTypeName);
idToArtifactTypeListMap.put(id, typeList);
} else {
Class artifactClass = Thread.currentThread().getContextClassLoader().loadClass(className);
// Already contains entry for this 'id', let's make sure it's the same Class
// which thus must implement >1 batch artifact "type" (i.e. contains >1 batch artifact annotation).
if (!idToArtifactClassMap.get(id).equals(artifactClass)) {
if (logger.isLoggable(Level.SEVERE)) {
Class alreadyLoaded = idToArtifactClassMap.get(id);
logger.severe("Attempted to load batch artifact with id: " + id + ", and className: " + className +
". Found: " + artifactClass + ", however the artifact id: " + id +
" is already associated with: " + alreadyLoaded + ", of className: " +
alreadyLoaded.getCanonicalName());
}
throw new IllegalArgumentException("Already loaded a different class for id = " + id);
}
List typeList = idToArtifactTypeListMap.get(id);
typeList.add(batchTypeName);
}
} catch (Exception e) {
throw new RuntimeException(e);
}
}
private Object getArtifactById(String id) {
Object artifactInstance = null;
try {
Class clazz = idToArtifactClassMap.get(id);
if (clazz != null) {
artifactInstance = (idToArtifactClassMap.get(id)).newInstance();
}
} catch (IllegalAccessException e) {
throw new BatchContainerRuntimeException("Tried but failed to load artifact with id: " + id, e);
} catch (InstantiationException e) {
throw new BatchContainerRuntimeException("Tried but failed to load artifact with id: " + id, e);
}
return artifactInstance;
}
private List getBatchTypeList(String id) {
return idToArtifactTypeListMap.get(id);
}
}
@Override
public void init(IBatchConfig batchConfig) throws BatchContainerServiceException {
// TODO Auto-generated method stub
}
@Override
public void shutdown() throws BatchContainerServiceException {
// TODO Auto-generated method stub
}
}
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