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* regarding copyright ownership. The ASF licenses this file *
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package org.apache.james.container.spring.osgi;
import java.net.URL;
import java.util.Enumeration;
import org.apache.commons.configuration.HierarchicalConfiguration;
import org.apache.james.container.spring.lifecycle.ConfigurationProvider;
import org.osgi.framework.Bundle;
import org.osgi.framework.BundleContext;
import org.osgi.framework.BundleEvent;
import org.osgi.framework.BundleListener;
import org.osgi.framework.ServiceReference;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.support.BeanDefinitionBuilder;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.context.ApplicationContext;
import org.springframework.osgi.context.BundleContextAware;
import org.springframework.osgi.context.support.AbstractDelegatedExecutionApplicationContext;
import org.springframework.osgi.service.exporter.OsgiServicePropertiesResolver;
import org.springframework.osgi.service.exporter.support.OsgiServiceFactoryBean;
/**
* This {@link BundleListener} use the extender pattern to scan all loaded
* bundles if a class name with a given name is present. If so it register in
* the {@link BeanDefinitionRegistry} and also register it to the OSG-Registry via an {@link OsgiServiceFactoryBean}
*
*/
public abstract class AbstractBundleTracker implements BeanFactoryAware, BundleListener, BundleContextAware, InitializingBean, DisposableBean {
private BundleContext context;
private String configuredClass;
private volatile OsgiServiceFactoryBean osgiFactoryBean;
private BeanFactory factory;
private final Logger logger = LoggerFactory.getLogger(AbstractBundleTracker.class);
@Override
public void setBeanFactory(BeanFactory factory) throws BeansException {
this.factory = factory;
}
@Override
public void setBundleContext(BundleContext context) {
this.context = context;
}
@Override
public void bundleChanged(BundleEvent event) {
Bundle b = event.getBundle();
// Check if the event was fired for this class
if (b.equals(this.context.getBundle())) {
return;
}
switch (event.getType()) {
case BundleEvent.STARTED:
Enumeration<?> entrs = b.findEntries("/", "*.class", true);
if (entrs != null) {
// Loop over all the classes
while (entrs.hasMoreElements()) {
URL e = (URL) entrs.nextElement();
String file = e.getFile();
String className = file.replaceAll("/", ".").replaceAll(".class", "").replaceFirst(".", "");
if (className.equals(configuredClass)) {
try {
BeanFactory bFactory = getBeanFactory(b.getBundleContext());
Class<?> clazz = getServiceClass();
// Create the definition and register it
BeanDefinitionRegistry registry = (BeanDefinitionRegistry) bFactory;
BeanDefinition def = BeanDefinitionBuilder.genericBeanDefinition(className).getBeanDefinition();
registry.registerBeanDefinition(getComponentName(), def);
// register the bean as service in the OSGI-Registry
osgiFactoryBean = new OsgiServiceFactoryBean();
osgiFactoryBean.setTargetBeanName(getComponentName());
osgiFactoryBean.setBeanFactory(bFactory);
osgiFactoryBean.setBundleContext(b.getBundleContext());
osgiFactoryBean.setInterfaces(new Class[] { clazz });
osgiFactoryBean.afterPropertiesSet();
logger.debug("Registered " + configuredClass + " in the OSGI-Registry with interface " + clazz.getName());
} catch (Exception e1) {
logger.error("Unable to register " + configuredClass + " in the OSGI-Registry", e1);
}
}
}
}
break;
case BundleEvent.STOPPED:
// check if we need to destroy the OsgiFactoryBean. This also include the unregister from the OSGI-Registry
if (osgiFactoryBean != null) {
osgiFactoryBean.destroy();
osgiFactoryBean = null;
logger.debug("Unregistered " + configuredClass + " in the OSGI-Registry with interface " + getServiceClass().getName());
}
break;
default:
break;
}
}
/**
* Return the {@link BeanFactory} for the given {@link BundleContext}. If none can be found we just create a new {@link AbstractDelegatedExecutionApplicationContext} and return the {@link BeanFactory} of it
*
*
* @param bundleContext
* @return factory
* @throws Exception
*/
private BeanFactory getBeanFactory(final BundleContext bundleContext) throws Exception {
final String filter = "(" + OsgiServicePropertiesResolver.BEAN_NAME_PROPERTY_KEY + "=" + bundleContext.getBundle().getSymbolicName() + ")";
final ServiceReference[] applicationContextRefs = bundleContext.getServiceReferences(ApplicationContext.class.getName(), filter);
// Check if we found an ApplicationContext. If not create one
if(applicationContextRefs == null || applicationContextRefs.length != 1) {
// Create a new context which just serve as registry later
AbstractDelegatedExecutionApplicationContext context = new AbstractDelegatedExecutionApplicationContext() {
};
context.setBundleContext(bundleContext);
context.setPublishContextAsService(true);
context.refresh();
return context.getBeanFactory();
} else {
return ((ApplicationContext) bundleContext.getService(applicationContextRefs[0])).getAutowireCapableBeanFactory();
}
}
@Override
public void afterPropertiesSet() throws Exception {
ConfigurationProvider confProvider = factory.getBean(ConfigurationProvider.class);
HierarchicalConfiguration config = confProvider.getConfiguration(getComponentName());
// Get the configuration for the class
configuredClass = config.getString("[@class]");
if (context != null) {
context.addBundleListener(this);
}
}
@Override
public void destroy() throws Exception {
// Its time to unregister the listener so we are sure resources are released
if (context != null) {
context.removeBundleListener(this);
}
}
/**
* Return the name of the component
*
* @return name
*/
protected abstract String getComponentName();
/**
* Return the class which will be used to expose the service in the OSGI
* registry
*
* @return sClass
*/
protected abstract Class<?> getServiceClass();
}