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/**
*
* 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.qpid.server.filter;
//
// Based on like named file from r450141 of the Apache ActiveMQ project <http://www.activemq.org/site/home.html>
//
import org.apache.log4j.Logger;
import org.apache.qpid.AMQException;
import org.apache.qpid.server.queue.Filterable;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
/**
* Used to evaluate an XPath Expression in a JMS selector.
*/
public final class XPathExpression implements BooleanExpression {
private static final Logger log = Logger.getLogger(XPathExpression.class);
private static final String EVALUATOR_SYSTEM_PROPERTY = "org.apache.qpid.server.filter.XPathEvaluatorClassName";
private static final String DEFAULT_EVALUATOR_CLASS_NAME=XalanXPathEvaluator.class.getName();
private static final Constructor EVALUATOR_CONSTRUCTOR;
static {
String cn = System.getProperty(EVALUATOR_SYSTEM_PROPERTY, DEFAULT_EVALUATOR_CLASS_NAME);
Constructor m = null;
try {
try {
m = getXPathEvaluatorConstructor(cn);
} 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 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});
}
private final String xpath;
private final XPathEvaluator evaluator;
static public interface XPathEvaluator {
public boolean evaluate(Filterable message);
}
XPathExpression(String xpath) {
this.xpath = xpath;
this.evaluator = createEvaluator(xpath);
}
private XPathEvaluator createEvaluator(String xpath2) {
try {
return (XPathEvaluator)EVALUATOR_CONSTRUCTOR.newInstance(new Object[]{xpath});
} 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(Filterable message) {
// try {
//FIXME this is flow to disk work
// if( message.isDropped() )
// return null;
return evaluator.evaluate(message) ? Boolean.TRUE : Boolean.FALSE;
// } catch (IOException e) {
//
// JMSException exception = new JMSException(e.getMessage());
// exception.initCause(e);
// throw exception;
//
// }
}
public String toString() {
return "XPATH "+ConstantExpression.encodeString(xpath);
}
/**
* @param message
* @return true if the expression evaluates to Boolean.TRUE.
* @throws AMQException
*/
public boolean matches(Filterable message)
{
Object object = evaluate(message);
return object!=null && object==Boolean.TRUE;
}
}
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