001/**
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.camel.builder.xml;
018
019import java.util.HashMap;
020import java.util.Map;
021
022import javax.xml.namespace.QName;
023import javax.xml.xpath.XPathVariableResolver;
024
025import org.apache.camel.Exchange;
026import org.apache.camel.Message;
027import org.slf4j.Logger;
028import org.slf4j.LoggerFactory;
029
030import static org.apache.camel.builder.xml.Namespaces.ENVIRONMENT_VARIABLES;
031import static org.apache.camel.builder.xml.Namespaces.EXCHANGE_PROPERTY;
032import static org.apache.camel.builder.xml.Namespaces.IN_NAMESPACE;
033import static org.apache.camel.builder.xml.Namespaces.OUT_NAMESPACE;
034import static org.apache.camel.builder.xml.Namespaces.SYSTEM_PROPERTIES_NAMESPACE;
035
036/**
037 * A variable resolver for XPath expressions which support properties on the
038 * message, exchange as well as making system properties and environment
039 * properties available.
040 * <p/>
041 * Implementations of this resolver must be thread safe
042 *
043 * @version 
044 */
045public class MessageVariableResolver implements XPathVariableResolver {
046    private static final Logger LOG = LoggerFactory.getLogger(MessageVariableResolver.class);
047
048    private Map<String, Object> variables = new HashMap<String, Object>();
049    private final ThreadLocal<Exchange> exchange;
050
051    public MessageVariableResolver(ThreadLocal<Exchange> exchange) {
052        this.exchange = exchange;
053    }
054
055    public Object resolveVariable(QName name) {
056        String uri = name.getNamespaceURI();
057        String localPart = name.getLocalPart();
058        Object answer = null;
059
060        Message in = exchange.get().getIn();
061        if (uri == null || uri.length() == 0) {
062            answer = variables.get(localPart);
063            if (answer == null) {
064                Message message = in;
065                if (message != null) {
066                    answer = message.getHeader(localPart);
067                }
068                if (answer == null) {
069                    answer = exchange.get().getProperty(localPart);
070                }
071            }
072        } else if (uri.equals(SYSTEM_PROPERTIES_NAMESPACE)) {
073            try {
074                answer = System.getProperty(localPart);
075            } catch (Exception e) {
076                LOG.debug("Security exception evaluating system property: " + localPart + ". Reason: " + e, e);
077            }
078        } else if (uri.equals(ENVIRONMENT_VARIABLES)) {
079            answer = System.getenv().get(localPart);
080        } else if (uri.equals(EXCHANGE_PROPERTY)) {
081            answer = exchange.get().getProperty(localPart);
082        } else if (uri.equals(IN_NAMESPACE)) {
083            answer = in.getHeader(localPart);
084            if (answer == null && localPart.equals("body")) {
085                answer = in.getBody();
086            }
087        } else if (uri.equals(OUT_NAMESPACE)) {
088            if (exchange.get().hasOut()) {
089                Message out = exchange.get().getOut();
090                answer = out.getHeader(localPart);
091                if (answer == null && localPart.equals("body")) {
092                    answer = out.getBody();
093                }
094            }
095        }
096
097        // if we can't find an answer we must return an empty String.
098        // if we return null, then the JDK default XPathEngine will throw an exception
099        if (answer == null) {
100            return "";
101        } else {
102            return answer;
103        }
104    }
105
106    public void addVariable(String localPart, Object value) {
107        variables.put(localPart, value);
108    }
109}