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ActiveMQ example source code file (XPathExpression.java)
The ActiveMQ XPathExpression.java source code/** * 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 javax.jms.JMSException; 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 = 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 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}); } 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(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; } } Other ActiveMQ examples (source code examples)Here is a short list of links related to this ActiveMQ XPathExpression.java source code file: |
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