/**
* 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.activemq.filter;
import java.io.IOException;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import javax.jms.JMSException;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import org.apache.activemq.command.Message;
import org.apache.activemq.util.JMSExceptionSupport;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Used to evaluate an XPath Expression in a JMS selector.
*/
public final class XPathExpression implements BooleanExpression {
private static final Logger LOG = LoggerFactory.getLogger(XPathExpression.class);
private static final String EVALUATOR_SYSTEM_PROPERTY = "org.apache.activemq.XPathEvaluatorClassName";
private static final String DEFAULT_EVALUATOR_CLASS_NAME = "org.apache.activemq.filter.XalanXPathEvaluator";
public static final String DOCUMENT_BUILDER_FACTORY_FEATURE = "org.apache.activemq.documentBuilderFactory.feature";
private static final Constructor EVALUATOR_CONSTRUCTOR;
private static DocumentBuilder builder = null;
static {
String cn = System.getProperty(EVALUATOR_SYSTEM_PROPERTY, DEFAULT_EVALUATOR_CLASS_NAME);
Constructor m = null;
try {
try {
m = getXPathEvaluatorConstructor(cn);
DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance();
builderFactory.setNamespaceAware(true);
builderFactory.setIgnoringElementContentWhitespace(true);
builderFactory.setIgnoringComments(true);
try {
// set some reasonable defaults
builderFactory.setFeature("http://xml.org/sax/features/external-general-entities", false);
builderFactory.setFeature("http://xml.org/sax/features/external-parameter-entities", false);
builderFactory.setFeature("http://apache.org/xml/features/disallow-doctype-decl", true);
} catch (ParserConfigurationException e) {
LOG.warn("Error setting document builder factory feature", e);
}
// setup the feature from the system property
setupFeatures(builderFactory);
builder = builderFactory.newDocumentBuilder();
} catch (Throwable e) {
LOG.warn("Invalid " + XPathEvaluator.class.getName() + " implementation: " + cn + ", reason: " + e, e);
cn = DEFAULT_EVALUATOR_CLASS_NAME;
try {
m = getXPathEvaluatorConstructor(cn);
} catch (Throwable e2) {
LOG.error("Default XPath evaluator could not be loaded", e);
}
}
} finally {
EVALUATOR_CONSTRUCTOR = m;
}
}
private final String xpath;
private final XPathEvaluator evaluator;
public static interface XPathEvaluator {
boolean evaluate(Message message) throws JMSException;
}
XPathExpression(String xpath) {
this.xpath = xpath;
this.evaluator = createEvaluator(xpath);
}
private static Constructor getXPathEvaluatorConstructor(String cn) throws ClassNotFoundException, SecurityException, NoSuchMethodException {
Class c = XPathExpression.class.getClassLoader().loadClass(cn);
if (!XPathEvaluator.class.isAssignableFrom(c)) {
throw new ClassCastException("" + c + " is not an instance of " + XPathEvaluator.class);
}
return c.getConstructor(new Class[] {String.class, DocumentBuilder.class});
}
protected static void setupFeatures(DocumentBuilderFactory factory) {
Properties properties = System.getProperties();
List<String> features = new ArrayList<String>();
for (Map.Entry<Object, Object> prop : properties.entrySet()) {
String key = (String) prop.getKey();
if (key.startsWith(DOCUMENT_BUILDER_FACTORY_FEATURE)) {
String uri = key.split(DOCUMENT_BUILDER_FACTORY_FEATURE + ":")[1];
Boolean value = Boolean.valueOf((String)prop.getValue());
try {
factory.setFeature(uri, value);
features.add("feature " + uri + " value " + value);
} catch (ParserConfigurationException e) {
LOG.warn("DocumentBuilderFactory doesn't support the feature {} with value {}, due to {}.", new Object[]{uri, value, e});
}
}
}
if (features.size() > 0) {
StringBuffer featureString = new StringBuffer();
// just log the configured feature
for (String feature : features) {
if (featureString.length() != 0) {
featureString.append(", ");
}
featureString.append(feature);
}
}
}
private XPathEvaluator createEvaluator(String xpath2) {
try {
return (XPathEvaluator)EVALUATOR_CONSTRUCTOR.newInstance(new Object[] {xpath, builder});
} catch (InvocationTargetException e) {
Throwable cause = e.getCause();
if (cause instanceof RuntimeException) {
throw (RuntimeException)cause;
}
throw new RuntimeException("Invalid XPath Expression: " + xpath + " reason: " + e.getMessage(), e);
} catch (Throwable e) {
throw new RuntimeException("Invalid XPath Expression: " + xpath + " reason: " + e.getMessage(), e);
}
}
public Object evaluate(MessageEvaluationContext message) throws JMSException {
try {
if (message.isDropped()) {
return null;
}
return evaluator.evaluate(message.getMessage()) ? Boolean.TRUE : Boolean.FALSE;
} catch (IOException e) {
throw JMSExceptionSupport.create(e);
}
}
public String toString() {
return "XPATH " + ConstantExpression.encodeString(xpath);
}
/**
* @param message
* @return true if the expression evaluates to Boolean.TRUE.
* @throws JMSException
*/
public boolean matches(MessageEvaluationContext message) throws JMSException {
Object object = evaluate(message);
return object != null && object == Boolean.TRUE;
}
}