/**
* 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.component.velocity;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.StringReader;
import java.io.StringWriter;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Properties;
import org.apache.camel.Exchange;
import org.apache.camel.ExchangePattern;
import org.apache.camel.Message;
import org.apache.camel.component.ResourceEndpoint;
import org.apache.camel.util.ExchangeHelper;
import org.apache.camel.util.IOHelper;
import org.apache.camel.util.ObjectHelper;
import org.apache.camel.util.ResourceHelper;
import org.apache.velocity.VelocityContext;
import org.apache.velocity.app.Velocity;
import org.apache.velocity.app.VelocityEngine;
import org.apache.velocity.context.Context;
import org.apache.velocity.runtime.log.CommonsLogLogChute;
/**
* @version
*/
public class VelocityEndpoint extends ResourceEndpoint {
private VelocityEngine velocityEngine;
private boolean loaderCache = true;
private String encoding;
private String propertiesFile;
public VelocityEndpoint() {
}
public VelocityEndpoint(String uri, VelocityComponent component, String resourceUri) {
super(uri, component, resourceUri);
}
@Override
public boolean isSingleton() {
return true;
}
@Override
public ExchangePattern getExchangePattern() {
return ExchangePattern.InOut;
}
@Override
protected String createEndpointUri() {
return "velocity:" + getResourceUri();
}
private synchronized VelocityEngine getVelocityEngine() throws Exception {
if (velocityEngine == null) {
velocityEngine = new VelocityEngine();
Properties properties = new Properties();
// load the velocity properties from property file
if (ObjectHelper.isNotEmpty(getPropertiesFile())) {
InputStream reader = ResourceHelper.resolveMandatoryResourceAsInputStream(getCamelContext().getClassResolver(), getPropertiesFile());
try {
properties.load(reader);
log.info("Loaded the velocity configuration file " + getPropertiesFile());
} finally {
IOHelper.close(reader, getPropertiesFile(), log);
}
}
// set the class resolver as a property so we can access it from CamelVelocityClasspathResourceLoader
velocityEngine.addProperty("CamelClassResolver", getCamelContext().getClassResolver());
// set regular properties
properties.setProperty(Velocity.FILE_RESOURCE_LOADER_CACHE, isLoaderCache() ? "true" : "false");
properties.setProperty(Velocity.RESOURCE_LOADER, "file, class");
properties.setProperty("class.resource.loader.description", "Camel Velocity Classpath Resource Loader");
properties.setProperty("class.resource.loader.class", CamelVelocityClasspathResourceLoader.class.getName());
properties.setProperty(Velocity.RUNTIME_LOG_LOGSYSTEM_CLASS, CommonsLogLogChute.class.getName());
properties.setProperty(CommonsLogLogChute.LOGCHUTE_COMMONS_LOG_NAME, VelocityEndpoint.class.getName());
log.debug("Initializing VelocityEngine with properties {}", properties);
// help the velocityEngine to load the CamelVelocityClasspathResourceLoader
ClassLoader old = Thread.currentThread().getContextClassLoader();
try {
ClassLoader delegate = new CamelVelocityDelegateClassLoader(old);
Thread.currentThread().setContextClassLoader(delegate);
velocityEngine.init(properties);
} finally {
Thread.currentThread().setContextClassLoader(old);
}
}
return velocityEngine;
}
public void setVelocityEngine(VelocityEngine velocityEngine) {
this.velocityEngine = velocityEngine;
}
public boolean isLoaderCache() {
return loaderCache;
}
/**
* Enables / disables the velocity resource loader cache which is enabled by default
*
* @param loaderCache a flag to enable/disable the cache
*/
public void setLoaderCache(boolean loaderCache) {
this.loaderCache = loaderCache;
}
public void setEncoding(String encoding) {
this.encoding = encoding;
}
public String getEncoding() {
return encoding;
}
public void setPropertiesFile(String file) {
propertiesFile = file;
}
public String getPropertiesFile() {
return propertiesFile;
}
public VelocityEndpoint findOrCreateEndpoint(String uri, String newResourceUri) {
String newUri = uri.replace(getResourceUri(), newResourceUri);
log.debug("Getting endpoint with URI: {}", newUri);
return (VelocityEndpoint) getCamelContext().getEndpoint(newUri);
}
@SuppressWarnings("unchecked")
@Override
protected void onExchange(Exchange exchange) throws Exception {
String path = getResourceUri();
ObjectHelper.notNull(path, "resourceUri");
String newResourceUri = exchange.getIn().getHeader(VelocityConstants.VELOCITY_RESOURCE_URI, String.class);
if (newResourceUri != null) {
exchange.getIn().removeHeader(VelocityConstants.VELOCITY_RESOURCE_URI);
log.debug("{} set to {} creating new endpoint to handle exchange", VelocityConstants.VELOCITY_RESOURCE_URI, newResourceUri);
VelocityEndpoint newEndpoint = findOrCreateEndpoint(getEndpointUri(), newResourceUri);
newEndpoint.onExchange(exchange);
return;
}
Reader reader;
String content = exchange.getIn().getHeader(VelocityConstants.VELOCITY_TEMPLATE, String.class);
if (content != null) {
// use content from header
reader = new StringReader(content);
if (log.isDebugEnabled()) {
log.debug("Velocity content read from header {} for endpoint {}", VelocityConstants.VELOCITY_TEMPLATE, getEndpointUri());
}
// remove the header to avoid it being propagated in the routing
exchange.getIn().removeHeader(VelocityConstants.VELOCITY_TEMPLATE);
} else {
if (log.isDebugEnabled()) {
log.debug("Velocity content read from resource {} with resourceUri: {} for endpoint {}", new Object[]{getResourceUri(), path, getEndpointUri()});
}
reader = getEncoding() != null ? new InputStreamReader(getResourceAsInputStream(), getEncoding()) : new InputStreamReader(getResourceAsInputStream());
}
// getResourceAsInputStream also considers the content cache
StringWriter buffer = new StringWriter();
String logTag = getClass().getName();
Map variableMap = ExchangeHelper.createVariableMap(exchange);
Context velocityContext = new VelocityContext(variableMap);
// let velocity parse and generate the result in buffer
VelocityEngine engine = getVelocityEngine();
log.debug("Velocity is evaluating using velocity context: {}", variableMap);
engine.evaluate(velocityContext, buffer, logTag, reader);
// now lets output the results to the exchange
Message out = exchange.getOut();
out.setBody(buffer.toString());
Map<String, Object> headers = (Map<String, Object>) velocityContext.get("headers");
for (Entry<String, Object> entry : headers.entrySet()) {
out.setHeader(entry.getKey(), entry.getValue());
}
}
}