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Camel with OSGi SCR (Declarative Services)
/**
* 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.scr;
import java.io.File;
import java.lang.reflect.Field;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.net.URI;
import java.net.URL;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;
import org.apache.camel.CamelContext;
import org.apache.camel.RoutesBuilder;
import org.apache.camel.component.properties.PropertiesComponent;
import org.apache.camel.core.osgi.OsgiCamelContextPublisher;
import org.apache.camel.core.osgi.OsgiDefaultCamelContext;
import org.apache.camel.core.osgi.utils.BundleDelegatingClassLoader;
import org.apache.camel.impl.DefaultCamelContext;
import org.apache.camel.impl.ExplicitCamelContextNameStrategy;
import org.apache.camel.impl.SimpleRegistry;
import org.apache.camel.spi.Registry;
import org.apache.camel.util.ReflectionHelper;
import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceReference;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public abstract class AbstractCamelRunner implements Runnable {
public static final int START_DELAY = 5000;
public static final String PROPERTY_PREFIX = "camel.scr.properties.prefix";
protected Logger log = LoggerFactory.getLogger(getClass());
// Configured fields
private String camelContextId;
private boolean active;
private CamelContext context;
private ScheduledExecutorService executor = Executors.newSingleThreadScheduledExecutor();
private ScheduledFuture starter;
private volatile boolean activated;
private volatile boolean started;
public final synchronized void activate(final BundleContext bundleContext, final Map props) throws Exception {
if (activated) {
return;
}
log.debug("activated!");
activated = true;
prepare(bundleContext, props);
runWithDelay(this);
}
public final synchronized void prepare(final BundleContext bundleContext, final Map props) throws Exception {
createCamelContext(bundleContext, props);
// Configure fields from properties
configure(context, this, log, true);
setupCamelContext(bundleContext, camelContextId);
}
protected void createCamelContext(final BundleContext bundleContext, final Map props) {
if (bundleContext != null) {
context = new OsgiDefaultCamelContext(bundleContext, createRegistry(bundleContext));
// Setup the application context classloader with the bundle classloader
context.setApplicationContextClassLoader(new BundleDelegatingClassLoader(bundleContext.getBundle()));
// and make sure the TCCL is our classloader
Thread.currentThread().setContextClassLoader(context.getApplicationContextClassLoader());
} else {
context = new DefaultCamelContext(createRegistry());
}
setupPropertiesComponent(context, props, log);
}
protected void setupCamelContext(final BundleContext bundleContext, final String camelContextId) throws Exception {
// Set up CamelContext
if (camelContextId != null) {
context.setNameStrategy(new ExplicitCamelContextNameStrategy(camelContextId));
}
// Add routes
for (RoutesBuilder route : getRouteBuilders()) {
context.addRoutes(configure(context, route, log));
}
// ensure we publish this CamelContext to the OSGi service registry
context.getManagementStrategy().addEventNotifier(new OsgiCamelContextPublisher(bundleContext));
}
public static void setupPropertiesComponent(final CamelContext context, final Map props, Logger log) {
// Set up PropertiesComponent
PropertiesComponent pc = new PropertiesComponent();
if (context.getComponentNames().contains("properties")) {
pc = context.getComponent("properties", PropertiesComponent.class);
} else {
context.addComponent("properties", pc);
}
// Set property prefix
if (System.getProperty(PROPERTY_PREFIX) != null) {
pc.setPropertyPrefix(System.getProperty(PROPERTY_PREFIX) + ".");
}
if (props != null) {
Properties initialProps = new Properties();
initialProps.putAll(props);
log.debug(String.format("Added %d initial properties", props.size()));
pc.setInitialProperties(initialProps);
}
}
protected abstract List getRouteBuilders() throws Exception;
// Run after a delay unless the method is called again
private void runWithDelay(final Runnable runnable) {
if (activated && !started) {
cancelDelayedRun();
// Run after a delay
starter = executor.schedule(runnable, START_DELAY, TimeUnit.MILLISECONDS);
}
}
private void cancelDelayedRun() {
if (null != starter) {
// Cancel but don't interrupt
starter.cancel(false);
}
}
public final synchronized void run() {
startCamelContext();
}
public final synchronized void deactivate() {
if (!activated) {
return;
}
log.debug("deactivated!");
activated = false;
cancelDelayedRun();
stop();
}
public final synchronized void stop() {
stopCamelContext();
}
private void startCamelContext() {
if (started) {
return;
}
try {
if (!active) {
context.setAutoStartup(false);
}
context.start();
started = true;
} catch (Exception e) {
// we should have a better way - than just try every 5th second to try to start the bundle
log.warn("Failed to start Camel context. Will try again when more Camel components have been registered.", e);
}
}
private void stopCamelContext() {
if (!started) {
return;
}
try {
context.stop();
} catch (Exception e) {
log.warn("Failed to stop Camel context.", e);
} finally {
// Even if stopping failed we consider Camel context stopped
started = false;
}
}
public final CamelContext getContext() {
return context;
}
protected final void gotCamelComponent(final ServiceReference serviceReference) {
log.trace("Got a new Camel Component.");
runWithDelay(this);
}
protected final void lostCamelComponent(final ServiceReference serviceReference) {
log.trace("Lost a Camel Component.");
}
public static T configure(final CamelContext context, final T target, final Logger log) {
return configure(context, target, log, false);
}
public static T configure(final CamelContext context, final T target, final Logger log, final boolean deep) {
Class clazz = target.getClass();
log.debug("Configuring {}", clazz.getName());
Collection fields = new ArrayList();
fields.addAll(Arrays.asList(clazz.getDeclaredFields()));
if (deep) {
fields.addAll(Arrays.asList(clazz.getFields()));
fields.addAll(Arrays.asList(clazz.getSuperclass().getDeclaredFields()));
}
for (Field field : fields) {
String propertyValue;
try {
propertyValue = context.resolvePropertyPlaceholders("{{" + field.getName() + "}}");
} catch (Exception e) {
log.debug("Skipped field {}", field.getName());
continue;
}
try {
if (!propertyValue.isEmpty()) {
// Try to convert the value and set the field
Object convertedValue = convertValue(propertyValue, field.getGenericType());
ReflectionHelper.setField(field, target, convertedValue);
log.debug("Configured field {} with value {}", field.getName(), propertyValue);
}
} catch (Exception e) {
log.warn("Error setting field " + field.getName() + " due: " + e.getMessage() + ". This exception is ignored.", e);
}
}
return target;
}
public static Object convertValue(final String value, final Type type) throws Exception {
Class clazz = null;
if (type instanceof ParameterizedType) {
clazz = (Class) ((ParameterizedType) type).getRawType();
} else if (type instanceof Class) {
clazz = (Class) type;
}
if (clazz != null && value != null) {
if (clazz.isAssignableFrom(value.getClass())) {
return clazz.cast(value);
} else if (clazz == Boolean.class || clazz == boolean.class) {
return Boolean.parseBoolean(value);
} else if (clazz == Integer.class || clazz == int.class) {
return Integer.parseInt(value);
} else if (clazz == Long.class || clazz == long.class) {
return Long.parseLong(value);
} else if (clazz == Double.class || clazz == double.class) {
return Double.parseDouble(value);
} else if (clazz == File.class) {
return new File(value);
} else if (clazz == URI.class) {
return new URI(value);
} else if (clazz == URL.class) {
return new URL(value);
} else {
throw new IllegalArgumentException("Unsupported type: " + clazz.getName());
}
} else {
return null;
}
}
public static T getRegistry(CamelContext context, Class type) throws Exception {
T result = context.getRegistry(type);
if (result == null) {
throw new Exception(type.getName() + " not available in " + context.getName());
}
return result;
}
protected Registry createRegistry() {
return new SimpleRegistry();
}
protected Registry createRegistry(BundleContext bundleContext) {
return createRegistry();
}
}
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