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The Core Camel Java DSL based router
/**
* 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.camel.builder.xml;
import java.util.HashMap;
import java.util.Map;
import javax.xml.namespace.QName;
import javax.xml.xpath.XPathVariableResolver;
import org.apache.camel.Exchange;
import org.apache.camel.Message;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import static org.apache.camel.builder.xml.Namespaces.ENVIRONMENT_VARIABLES;
import static org.apache.camel.builder.xml.Namespaces.EXCHANGE_PROPERTY;
import static org.apache.camel.builder.xml.Namespaces.IN_NAMESPACE;
import static org.apache.camel.builder.xml.Namespaces.OUT_NAMESPACE;
import static org.apache.camel.builder.xml.Namespaces.SYSTEM_PROPERTIES_NAMESPACE;
/**
* A variable resolver for XPath expressions which support properties on the
* message, exchange as well as making system properties and environment
* properties available.
*
* Implementations of this resolver must be thread safe
*
* @version
*/
public class MessageVariableResolver implements XPathVariableResolver {
private static final Logger LOG = LoggerFactory.getLogger(MessageVariableResolver.class);
private Map variables = new HashMap<>();
private final ThreadLocal exchange;
public MessageVariableResolver(ThreadLocal exchange) {
this.exchange = exchange;
}
public Object resolveVariable(QName name) {
String uri = name.getNamespaceURI();
String localPart = name.getLocalPart();
Object answer = null;
Message in = exchange.get().getIn();
if (uri == null || uri.length() == 0) {
answer = variables.get(localPart);
if (answer == null) {
Message message = in;
if (message != null) {
answer = message.getHeader(localPart);
}
if (answer == null) {
answer = exchange.get().getProperty(localPart);
}
}
} else if (uri.equals(SYSTEM_PROPERTIES_NAMESPACE)) {
try {
answer = System.getProperty(localPart);
} catch (Exception e) {
LOG.debug("Security exception evaluating system property: " + localPart + ". Reason: " + e, e);
}
} else if (uri.equals(ENVIRONMENT_VARIABLES)) {
answer = System.getenv().get(localPart);
} else if (uri.equals(EXCHANGE_PROPERTY)) {
answer = exchange.get().getProperty(localPart);
} else if (uri.equals(IN_NAMESPACE)) {
answer = in.getHeader(localPart);
if (answer == null && localPart.equals("body")) {
answer = in.getBody();
}
} else if (uri.equals(OUT_NAMESPACE)) {
if (exchange.get().hasOut()) {
Message out = exchange.get().getOut();
answer = out.getHeader(localPart);
if (answer == null && localPart.equals("body")) {
answer = out.getBody();
}
}
}
// if we can't find an answer we must return an empty String.
// if we return null, then the JDK default XPathEngine will throw an exception
if (answer == null) {
return "";
} else {
return answer;
}
}
public void addVariable(String localPart, Object value) {
variables.put(localPart, value);
}
}