/**
* 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.io.InputStream;
import java.io.StringReader;
import java.util.List;
import java.util.Map;
import java.util.Queue;
import java.util.concurrent.ConcurrentLinkedQueue;
import javax.xml.namespace.QName;
import javax.xml.transform.dom.DOMSource;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;
import javax.xml.xpath.XPathFactoryConfigurationException;
import javax.xml.xpath.XPathFunction;
import javax.xml.xpath.XPathFunctionException;
import javax.xml.xpath.XPathFunctionResolver;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;
import org.apache.camel.Exchange;
import org.apache.camel.Expression;
import org.apache.camel.Message;
import org.apache.camel.Predicate;
import org.apache.camel.RuntimeExpressionException;
import org.apache.camel.Service;
import org.apache.camel.component.bean.BeanInvocation;
import org.apache.camel.component.file.GenericFile;
import org.apache.camel.spi.NamespaceAware;
import org.apache.camel.util.ExchangeHelper;
import org.apache.camel.util.MessageHelper;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import static org.apache.camel.builder.xml.Namespaces.DEFAULT_NAMESPACE;
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.isMatchingNamespaceOrEmptyNamespace;
/**
* Creates an XPath expression builder which creates a nodeset result by default.
* If you want to evaluate a String expression then call {@link #stringResult()}
* <p/>
* An XPath object is not thread-safe and not reentrant. In other words, it is the application's responsibility to make
* sure that one XPath object is not used from more than one thread at any given time, and while the evaluate method
* is invoked, applications may not recursively call the evaluate method.
* <p/>
* This implementation is thread safe by using thread locals and pooling to allow concurrency
*
* @see XPathConstants#NODESET
*
* @version $Revision: 836037 $
*/
public class XPathBuilder implements Expression, Predicate, NamespaceAware, Service {
private static final transient Log LOG = LogFactory.getLog(XPathBuilder.class);
private final Queue<XPathExpression> pool = new ConcurrentLinkedQueue<XPathExpression>();
private final String text;
private final ThreadLocal<MessageVariableResolver> variableResolver = new ThreadLocal<MessageVariableResolver>();
private final ThreadLocal<Exchange> exchange = new ThreadLocal<Exchange>();
private XPathFactory xpathFactory;
private Class<?> documentType = Document.class;
// For some reason the default expression of "a/b" on a document such as
// <a><b>1</b><b>2</b></a>
// will evaluate as just "1" by default which is bizarre. So by default
// lets assume XPath expressions result in nodesets.
private Class<?> resultType;
private QName resultQName = XPathConstants.NODESET;
private String objectModelUri;
private DefaultNamespaceContext namespaceContext;
private XPathFunctionResolver functionResolver;
private XPathFunction bodyFunction;
private XPathFunction headerFunction;
private XPathFunction outBodyFunction;
private XPathFunction outHeaderFunction;
public XPathBuilder(String text) {
this.text = text;
}
public static XPathBuilder xpath(String text) {
return new XPathBuilder(text);
}
public static XPathBuilder xpath(String text, Class<?> resultType) {
XPathBuilder builder = new XPathBuilder(text);
builder.setResultType(resultType);
return builder;
}
@Override
public String toString() {
return "XPath: " + text;
}
public boolean matches(Exchange exchange) {
Object booleanResult = evaluateAs(exchange, XPathConstants.BOOLEAN);
return exchange.getContext().getTypeConverter().convertTo(Boolean.class, booleanResult);
}
public <T> T evaluate(Exchange exchange, Class<T> type) {
Object result = evaluate(exchange);
return exchange.getContext().getTypeConverter().convertTo(type, result);
}
// Builder methods
// -------------------------------------------------------------------------
/**
* Sets the expression result type to boolean
*
* @return the current builder
*/
public XPathBuilder booleanResult() {
resultQName = XPathConstants.BOOLEAN;
return this;
}
/**
* Sets the expression result type to boolean
*
* @return the current builder
*/
public XPathBuilder nodeResult() {
resultQName = XPathConstants.NODE;
return this;
}
/**
* Sets the expression result type to boolean
*
* @return the current builder
*/
public XPathBuilder nodeSetResult() {
resultQName = XPathConstants.NODESET;
return this;
}
/**
* Sets the expression result type to boolean
*
* @return the current builder
*/
public XPathBuilder numberResult() {
resultQName = XPathConstants.NUMBER;
return this;
}
/**
* Sets the expression result type to boolean
*
* @return the current builder
*/
public XPathBuilder stringResult() {
resultQName = XPathConstants.STRING;
return this;
}
/**
* Sets the expression result type to boolean
*
* @return the current builder
*/
public XPathBuilder resultType(Class<?> resultType) {
setResultType(resultType);
return this;
}
/**
* Sets the object model URI to use
*
* @return the current builder
*/
public XPathBuilder objectModel(String uri) {
this.objectModelUri = uri;
return this;
}
/**
* Sets the {@link XPathFunctionResolver} instance to use on these XPath
* expressions
*
* @return the current builder
*/
public XPathBuilder functionResolver(XPathFunctionResolver functionResolver) {
this.functionResolver = functionResolver;
return this;
}
/**
* Registers the namespace prefix and URI with the builder so that the
* prefix can be used in XPath expressions
*
* @param prefix is the namespace prefix that can be used in the XPath
* expressions
* @param uri is the namespace URI to which the prefix refers
* @return the current builder
*/
public XPathBuilder namespace(String prefix, String uri) {
getNamespaceContext().add(prefix, uri);
return this;
}
/**
* Registers namespaces with the builder so that the registered
* prefixes can be used in XPath expressions
*
* @param namespaces is namespaces object that should be used in the
* XPath expression
* @return the current builder
*/
public XPathBuilder namespaces(Namespaces namespaces) {
namespaces.configure(this);
return this;
}
/**
* Registers a variable (in the global namespace) which can be referred to
* from XPath expressions
*/
public XPathBuilder variable(String name, Object value) {
getVariableResolver().addVariable(name, value);
return this;
}
/**
* Configures the document type to use.
* <p/>
* The document type controls which kind of Class Camel should convert the payload
* to before doing the xpath evaluation.
* <p/>
* For example you can set it to {@link InputSource} to use SAX streams.
* By default Camel uses {@link Document} as the type.
*
* @param documentType the document type
* @return the current builder
*/
public XPathBuilder documentType(Class<?> documentType) {
setDocumentType(documentType);
return this;
}
// Properties
// -------------------------------------------------------------------------
public XPathFactory getXPathFactory() throws XPathFactoryConfigurationException {
if (xpathFactory == null) {
if (objectModelUri != null) {
xpathFactory = XPathFactory.newInstance(objectModelUri);
}
xpathFactory = XPathFactory.newInstance();
}
return xpathFactory;
}
public void setXPathFactory(XPathFactory xpathFactory) {
this.xpathFactory = xpathFactory;
}
public Class<?> getDocumentType() {
return documentType;
}
public void setDocumentType(Class<?> documentType) {
this.documentType = documentType;
}
public String getText() {
return text;
}
public QName getResultQName() {
return resultQName;
}
public void setResultQName(QName resultQName) {
this.resultQName = resultQName;
}
public DefaultNamespaceContext getNamespaceContext() {
if (namespaceContext == null) {
try {
DefaultNamespaceContext defaultNamespaceContext = new DefaultNamespaceContext(getXPathFactory());
populateDefaultNamespaces(defaultNamespaceContext);
namespaceContext = defaultNamespaceContext;
} catch (XPathFactoryConfigurationException e) {
throw new RuntimeExpressionException(e);
}
}
return namespaceContext;
}
public void setNamespaceContext(DefaultNamespaceContext namespaceContext) {
this.namespaceContext = namespaceContext;
}
public XPathFunctionResolver getFunctionResolver() {
return functionResolver;
}
public void setFunctionResolver(XPathFunctionResolver functionResolver) {
this.functionResolver = functionResolver;
}
public void setNamespaces(Map<String, String> namespaces) {
getNamespaceContext().setNamespaces(namespaces);
}
public XPathFunction getBodyFunction() {
if (bodyFunction == null) {
bodyFunction = new XPathFunction() {
@SuppressWarnings("unchecked")
public Object evaluate(List list) throws XPathFunctionException {
if (exchange == null) {
return null;
}
return exchange.get().getIn().getBody();
}
};
}
return bodyFunction;
}
public void setBodyFunction(XPathFunction bodyFunction) {
this.bodyFunction = bodyFunction;
}
public XPathFunction getHeaderFunction() {
if (headerFunction == null) {
headerFunction = new XPathFunction() {
@SuppressWarnings("unchecked")
public Object evaluate(List list) throws XPathFunctionException {
if (exchange != null && !list.isEmpty()) {
Object value = list.get(0);
if (value != null) {
return exchange.get().getIn().getHeader(value.toString());
}
}
return null;
}
};
}
return headerFunction;
}
public void setHeaderFunction(XPathFunction headerFunction) {
this.headerFunction = headerFunction;
}
public XPathFunction getOutBodyFunction() {
if (outBodyFunction == null) {
outBodyFunction = new XPathFunction() {
@SuppressWarnings("unchecked")
public Object evaluate(List list) throws XPathFunctionException {
if (exchange.get() != null && exchange.get().hasOut()) {
return exchange.get().getOut().getBody();
}
return null;
}
};
}
return outBodyFunction;
}
public void setOutBodyFunction(XPathFunction outBodyFunction) {
this.outBodyFunction = outBodyFunction;
}
public XPathFunction getOutHeaderFunction() {
if (outHeaderFunction == null) {
outHeaderFunction = new XPathFunction() {
@SuppressWarnings("unchecked")
public Object evaluate(List list) throws XPathFunctionException {
if (exchange.get() != null && !list.isEmpty()) {
Object value = list.get(0);
if (value != null) {
return exchange.get().getOut().getHeader(value.toString());
}
}
return null;
}
};
}
return outHeaderFunction;
}
public void setOutHeaderFunction(XPathFunction outHeaderFunction) {
this.outHeaderFunction = outHeaderFunction;
}
public Class<?> getResultType() {
return resultType;
}
public void setResultType(Class<?> resultType) {
this.resultType = resultType;
if (Number.class.isAssignableFrom(resultType)) {
numberResult();
} else if (String.class.isAssignableFrom(resultType)) {
stringResult();
} else if (Boolean.class.isAssignableFrom(resultType)) {
booleanResult();
} else if (Node.class.isAssignableFrom(resultType)) {
nodeResult();
} else if (NodeList.class.isAssignableFrom(resultType)) {
nodeSetResult();
}
}
// Implementation methods
// -------------------------------------------------------------------------
protected Object evaluate(Exchange exchange) {
Object answer = evaluateAs(exchange, resultQName);
if (resultType != null) {
return ExchangeHelper.convertToType(exchange, resultType, answer);
}
return answer;
}
/**
* Evaluates the expression as the given result type
*/
protected Object evaluateAs(Exchange exchange, QName resultQName) {
// pool a pre compiled expression from pool
XPathExpression xpathExpression = pool.poll();
if (xpathExpression == null) {
LOG.trace("Creating new XPathExpression as none was available from pool");
// no avail in pool then create one
try {
xpathExpression = createXPathExpression();
} catch (XPathExpressionException e) {
throw new InvalidXPathExpression(getText(), e);
} catch (Exception e) {
throw new RuntimeExpressionException("Cannot create xpath expression", e);
}
} else {
LOG.trace("Acquired XPathExpression from pool");
}
try {
return doInEvaluateAs(xpathExpression, exchange, resultQName);
} finally {
// release it back to the pool
pool.add(xpathExpression);
LOG.trace("Released XPathExpression back to pool");
}
}
protected Object doInEvaluateAs(XPathExpression xpathExpression, Exchange exchange, QName resultQName) {
if (LOG.isTraceEnabled()) {
LOG.trace("Evaluating exchange: " + exchange + " as: " + resultQName);
}
Object answer;
// set exchange and variable resolver as thread locals for concurrency
this.exchange.set(exchange);
try {
Object document = getDocument(exchange);
if (resultQName != null) {
if (document instanceof InputSource) {
InputSource inputSource = (InputSource) document;
answer = xpathExpression.evaluate(inputSource, resultQName);
} else if (document instanceof DOMSource) {
DOMSource source = (DOMSource) document;
answer = xpathExpression.evaluate(source.getNode(), resultQName);
} else {
answer = xpathExpression.evaluate(document, resultQName);
}
} else {
if (document instanceof InputSource) {
InputSource inputSource = (InputSource) document;
answer = xpathExpression.evaluate(inputSource);
} else if (document instanceof DOMSource) {
DOMSource source = (DOMSource) document;
answer = xpathExpression.evaluate(source.getNode());
} else {
answer = xpathExpression.evaluate(document);
}
}
} catch (XPathExpressionException e) {
throw new InvalidXPathExpression(getText(), e);
}
if (LOG.isTraceEnabled()) {
LOG.trace("Done evaluating exchange: " + exchange + " as: " + resultQName + " with result: " + answer);
}
return answer;
}
protected XPathExpression createXPathExpression() throws XPathExpressionException, XPathFactoryConfigurationException {
XPath xPath = getXPathFactory().newXPath();
xPath.setNamespaceContext(getNamespaceContext());
xPath.setXPathVariableResolver(getVariableResolver());
XPathFunctionResolver parentResolver = getFunctionResolver();
if (parentResolver == null) {
parentResolver = xPath.getXPathFunctionResolver();
}
xPath.setXPathFunctionResolver(createDefaultFunctionResolver(parentResolver));
return xPath.compile(text);
}
/**
* Lets populate a number of standard prefixes if they are not already there
*/
protected void populateDefaultNamespaces(DefaultNamespaceContext context) {
setNamespaceIfNotPresent(context, "in", IN_NAMESPACE);
setNamespaceIfNotPresent(context, "out", OUT_NAMESPACE);
setNamespaceIfNotPresent(context, "env", Namespaces.ENVIRONMENT_VARIABLES);
setNamespaceIfNotPresent(context, "system", Namespaces.SYSTEM_PROPERTIES_NAMESPACE);
}
protected void setNamespaceIfNotPresent(DefaultNamespaceContext context, String prefix, String uri) {
if (context != null) {
String current = context.getNamespaceURI(prefix);
if (current == null) {
context.add(prefix, uri);
}
}
}
protected XPathFunctionResolver createDefaultFunctionResolver(final XPathFunctionResolver parent) {
return new XPathFunctionResolver() {
public XPathFunction resolveFunction(QName qName, int argumentCount) {
XPathFunction answer = null;
if (parent != null) {
answer = parent.resolveFunction(qName, argumentCount);
}
if (answer == null) {
if (isMatchingNamespaceOrEmptyNamespace(qName.getNamespaceURI(), IN_NAMESPACE)
|| isMatchingNamespaceOrEmptyNamespace(qName.getNamespaceURI(), DEFAULT_NAMESPACE)) {
String localPart = qName.getLocalPart();
if (localPart.equals("body") && argumentCount == 0) {
return getBodyFunction();
}
if (localPart.equals("header") && argumentCount == 1) {
return getHeaderFunction();
}
}
if (isMatchingNamespaceOrEmptyNamespace(qName.getNamespaceURI(), OUT_NAMESPACE)) {
String localPart = qName.getLocalPart();
if (localPart.equals("body") && argumentCount == 0) {
return getOutBodyFunction();
}
if (localPart.equals("header") && argumentCount == 1) {
return getOutHeaderFunction();
}
}
}
return answer;
}
};
}
/**
* Strategy method to extract the document from the exchange
*/
@SuppressWarnings("unchecked")
protected Object getDocument(Exchange exchange) {
Message in = exchange.getIn();
Class type = getDocumentType();
Object answer = null;
if (type != null) {
answer = in.getBody(type);
}
if (answer == null) {
answer = in.getBody();
}
// lets try coerce some common types into something JAXP can deal with
if (answer instanceof GenericFile) {
// special for files so we can work with them out of the box
InputStream is = exchange.getContext().getTypeConverter().convertTo(InputStream.class, answer);
answer = new InputSource(is);
} else if (answer instanceof BeanInvocation) {
// if its a null bean invocation then handle that
BeanInvocation bi = exchange.getContext().getTypeConverter().convertTo(BeanInvocation.class, answer);
if (bi.getArgs() != null && bi.getArgs().length == 1 && bi.getArgs()[0] == null) {
// its a null argument from the bean invocation so use null as answer
answer = null;
}
} else if (answer instanceof String) {
answer = new InputSource(new StringReader(answer.toString()));
}
// call the reset if the in message body is StreamCache
MessageHelper.resetStreamCache(exchange.getIn());
return answer;
}
private MessageVariableResolver getVariableResolver() {
MessageVariableResolver resolver = variableResolver.get();
if (resolver == null) {
resolver = new MessageVariableResolver(exchange);
variableResolver.set(resolver);
}
return resolver;
}
public void start() throws Exception {
}
public void stop() throws Exception {
pool.clear();
}
}