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* Licensed to the Apache Software Foundation (ASF) under one
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* 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.ofbiz.base.config;
import java.io.InputStream;
import java.net.URL;
import org.apache.ofbiz.base.util.Debug;
import org.apache.ofbiz.base.util.UtilURL;
import org.apache.ofbiz.base.util.UtilXml;
import org.apache.ofbiz.base.util.cache.UtilCache;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
/**
* Loads resources using dynamically specified resource loader classes.
*/
public abstract class ResourceLoader {
public static final String module = ResourceLoader.class.getName();
private static final UtilCache<String, ResourceLoader> loaderCache = UtilCache.createUtilCache("resource.ResourceLoaders", 0, 0);
// This cache is temporary - we will use it until the framework has been refactored to eliminate DOM tree caching, then it can be removed.
private static final UtilCache<String, Document> domCache = UtilCache.createUtilCache("resource.DomTrees", 0, 0);
public static InputStream loadResource(String xmlFilename, String location, String loaderName) throws GenericConfigException {
ResourceLoader loader = getLoader(xmlFilename, loaderName);
if (loader == null) {
throw new IllegalArgumentException("ResourceLoader not found with name [" + loaderName + "] in " + xmlFilename);
}
return loader.loadResource(location);
}
public static URL getURL(String xmlFilename, String location, String loaderName) throws GenericConfigException {
ResourceLoader loader = getLoader(xmlFilename, loaderName);
if (loader == null) {
throw new IllegalArgumentException("ResourceLoader not found with name [" + loaderName + "] in " + xmlFilename);
}
return loader.getURL(location);
}
public static ResourceLoader getLoader(String xmlFilename, String loaderName) throws GenericConfigException {
String cacheKey = xmlFilename.concat("#").concat(loaderName);
ResourceLoader loader = loaderCache.get(cacheKey);
if (loader == null) {
Element rootElement = null;
URL xmlUrl = UtilURL.fromResource(xmlFilename);
if (xmlUrl == null) {
throw new GenericConfigException("Could not find the " + xmlFilename + " file");
}
try {
rootElement = UtilXml.readXmlDocument(xmlUrl, true, true).getDocumentElement();
} catch (Exception e) {
throw new GenericConfigException("Exception thrown while reading " + xmlFilename + ": ", e);
}
Element loaderElement = UtilXml.firstChildElement(rootElement, "resource-loader", "name", loaderName);
if (loaderElement == null) {
throw new GenericConfigException("The " + xmlFilename + " file is missing the <resource-loader> element with the name " + loaderName);
}
if (loaderElement.getAttribute("class").isEmpty()) {
throw new GenericConfigException("The " + xmlFilename + " file <resource-loader> element with the name " + loaderName + " is missing the class attribute");
}
loader = loaderCache.putIfAbsentAndGet(cacheKey, makeLoader(loaderElement));
}
return loader;
}
/** This method should be avoided. DOM object trees take a lot of memory and they are not
* thread-safe, so they should not be cached.
* @deprecated use {@link #readXmlRootElement(String)}
*/
@Deprecated
public static Element getXmlRootElement(String xmlFilename) throws GenericConfigException {
Document document = ResourceLoader.getXmlDocument(xmlFilename);
if (document != null) {
return document.getDocumentElement();
} else {
return null;
}
}
public static Element readXmlRootElement(String xmlFilename) throws GenericConfigException {
Document document = ResourceLoader.readXmlDocument(xmlFilename);
if (document != null) {
return document.getDocumentElement();
} else {
return null;
}
}
public static void invalidateDocument(String xmlFilename) throws GenericConfigException {
UtilCache.clearCachesThatStartWith(xmlFilename);
}
/** This method should be avoided. DOM object trees take a lot of memory and they are not
* thread-safe, so they should not be cached.
* @deprecated use {@link #readXmlDocument(String)}
*/
@Deprecated
public static Document getXmlDocument(String xmlFilename) throws GenericConfigException {
Document document = domCache.get(xmlFilename);
if (document == null) {
document = readXmlDocument(xmlFilename);
if (document != null) {
document = (Document) domCache.putIfAbsentAndGet(xmlFilename, document);
}
}
return document;
}
public static Document readXmlDocument(String xmlFilename) throws GenericConfigException {
URL confUrl = UtilURL.fromResource(xmlFilename);
if (confUrl == null) {
throw new GenericConfigException("ERROR: could not find the [" + xmlFilename + "] XML file on the classpath");
}
try {
return UtilXml.readXmlDocument(confUrl, true, true);
} catch (org.xml.sax.SAXException e) {
throw new GenericConfigException("Error reading " + xmlFilename + "", e);
} catch (javax.xml.parsers.ParserConfigurationException e) {
throw new GenericConfigException("Error reading " + xmlFilename + "", e);
} catch (java.io.IOException e) {
throw new GenericConfigException("Error reading " + xmlFilename + "", e);
}
}
private static ResourceLoader makeLoader(Element loaderElement) throws GenericConfigException {
String loaderName = loaderElement.getAttribute("name");
String className = loaderElement.getAttribute("class");
ResourceLoader loader = null;
try {
Class<?> lClass = null;
ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
lClass = classLoader.loadClass(className);
loader = (ResourceLoader) lClass.newInstance();
loader.init(loaderName, loaderElement.getAttribute("prefix"), loaderElement.getAttribute("prepend-env"));
return loader;
} catch (Exception e) {
throw new GenericConfigException("Exception thrown while loading ResourceLoader class \"" + className + "\" ", e);
}
}
private String prefix;
private String envName;
protected ResourceLoader() {}
private void init(String name, String prefix, String envName) {
this.prefix = prefix;
this.envName = envName;
}
/**
* Just a utility method to be used in loadResource by the implementing class.
* @param location
* @return the built-up full location
*/
public String fullLocation(String location) {
StringBuilder buf = new StringBuilder();
if (!envName.isEmpty()) {
String propValue = System.getProperty(envName);
if (propValue == null) {
String errMsg = "The Java environment (-Dxxx=yyy) variable with name " + envName + " is not set, cannot load resource.";
Debug.logError(errMsg, module);
throw new IllegalArgumentException(errMsg);
}
buf.append(propValue);
}
buf.append(prefix);
buf.append(location);
return buf.toString();
}
public abstract InputStream loadResource(String location) throws GenericConfigException;
public abstract URL getURL(String location) throws GenericConfigException;
}