/*
* JBoss, Home of Professional Open Source
* Copyright 2009, Red Hat Middleware LLC, and individual contributors
* by the @authors tag. See the copyright.txt in the distribution for a
* full listing of individual contributors.
*
* Licensed 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.jboss.arquillian.impl;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.lang.reflect.Constructor;
import java.net.URL;
import java.util.Collection;
import java.util.Enumeration;
import java.util.LinkedHashSet;
import java.util.Set;
import java.util.logging.Logger;
import org.jboss.arquillian.spi.ServiceLoader;
/**
* ServiceLoader implementation that use META-INF/services/interface files to registered Services.
*
* @author <a href="mailto:aslak@conduct.no">Aslak Knutsen</a>
* @version $Revision: $
*/
public class DynamicServiceLoader implements ServiceLoader
{
//-------------------------------------------------------------------------------------||
// Class Members ----------------------------------------------------------------------||
//-------------------------------------------------------------------------------------||
private static Logger logger = Logger.getLogger(DynamicServiceLoader.class.getName());
private static final String SERVICES = "META-INF/services";
//-------------------------------------------------------------------------------------||
// Required Implementations - ServiceLoader -------------------------------------------||
//-------------------------------------------------------------------------------------||
/* (non-Javadoc)
* @see org.jboss.arquillian.spi.ServiceLoader#all(java.lang.Class)
*/
public <T> Collection<T> all(Class<T> serviceClass)
{
return all(SecurityActions.getThreadContextClassLoader(), serviceClass);
}
/* (non-Javadoc)
* @see org.jboss.arquillian.spi.ServiceLoader#all(java.lang.ClassLoader, java.lang.Class)
*/
@Override
public <T> Collection<T> all(ClassLoader classLoader, Class<T> serviceClass)
{
Validate.notNull(classLoader, "ClassLoader must be provided");
Validate.notNull(serviceClass, "ServiceClass must be provided");
return createInstances(
serviceClass,
load(serviceClass, classLoader));
}
/* (non-Javadoc)
* @see org.jboss.arquillian.spi.ServiceLoader#onlyOne(java.lang.Class)
*/
public <T> T onlyOne(Class<T> serviceClass)
{
return onlyOne(SecurityActions.getThreadContextClassLoader(), serviceClass);
}
/* (non-Javadoc)
* @see org.jboss.arquillian.spi.ServiceLoader#onlyOne(java.lang.ClassLoader, java.lang.Class)
*/
@Override
public <T> T onlyOne(ClassLoader classLoader, Class<T> serviceClass)
{
Validate.notNull(classLoader, "ClassLoader must be provided");
Validate.notNull(serviceClass, "ServiceClass must be provided");
Set<Class<? extends T>> serviceImpls = load(serviceClass, classLoader);
verifyOnlyOneOrSameImplementation(serviceClass, serviceImpls);
return createInstance(serviceImpls.iterator().next());
}
/* (non-Javadoc)
* @see org.jboss.arquillian.spi.ServiceLoader#onlyOne(java.lang.Class, java.lang.Class)
*/
public <T> T onlyOne(Class<T> serviceClass, Class<? extends T> defaultServiceClass)
{
return onlyOne(SecurityActions.getThreadContextClassLoader(), serviceClass, defaultServiceClass);
}
/* (non-Javadoc)
* @see org.jboss.arquillian.spi.ServiceLoader#onlyOne(java.lang.ClassLoader, java.lang.Class, java.lang.Class)
*/
@Override
public <T> T onlyOne(ClassLoader classLoader, Class<T> serviceClass, Class<? extends T> defaultServiceClass)
{
Validate.notNull(classLoader, "ClassLoader must be provided");
Validate.notNull(serviceClass, "ServiceClass must be provided");
Validate.notNull(defaultServiceClass, "DefaultServiceClass must be provided");
Class<? extends T> serviceImplToCreate = defaultServiceClass;
Set<Class<? extends T>> serviceImpls = load(serviceClass, classLoader);
if(serviceImpls.size() > 0)
{
verifySameImplementation(serviceClass, serviceImpls);
serviceImplToCreate = serviceImpls.iterator().next();
}
return createInstance(serviceImplToCreate);
}
//-------------------------------------------------------------------------------------||
// Internal Helper Methods ------------------------------------------------------------||
//-------------------------------------------------------------------------------------||
private <T> void verifyOnlyOneOrSameImplementation(Class<T> serviceClass, Collection<Class<? extends T>> providers)
{
if(providers == null || providers.size() == 0)
{
throw new IllegalStateException(
"No implementation found for " +
serviceClass.getName() + ", please check your classpath");
}
if(providers.size() > 1)
{
// verify that they all point to the same implementation, if not throw exception
verifySameImplementation(serviceClass, providers);
}
}
private <T> void verifySameImplementation(Class<T> serviceClass, Collection<Class<? extends T>> providers)
{
boolean providersAreTheSame = false;
Class<?> firstProvider = null;
for(Class<?> provider : providers)
{
if(firstProvider == null)
{
// set the class to match
firstProvider = provider;
continue;
}
if(firstProvider == provider)
{
providersAreTheSame = true;
}
else
{
throw new IllegalStateException(
"More then one implementation found for "
+ serviceClass.getName() + ", " +
"please check your classpath. The found implementations are " + toClassString(providers));
}
}
if(providersAreTheSame)
{
logger.warning(
"More then one reference to the same implementation was found for " +
serviceClass.getName() + ", please verify you classpath");
}
}
private <T> String toClassString(Collection<Class<? extends T>> providers)
{
StringBuilder sb = new StringBuilder();
for(Class<?> provider : providers)
{
sb.append(provider.getName()).append(", ");
}
return sb.subSequence(0, sb.length()-2).toString();
}
//-------------------------------------------------------------------------------------||
// Internal Helper Methods - Service Loading ------------------------------------------||
//-------------------------------------------------------------------------------------||
private <T> Set<Class<? extends T>> load(Class<T> serviceClass, ClassLoader loader)
{
String serviceFile = SERVICES + "/" + serviceClass.getName();
LinkedHashSet<Class<? extends T>> providers = new LinkedHashSet<Class<? extends T>>();
try
{
Enumeration<URL> enumeration = loader.getResources(serviceFile);
while (enumeration.hasMoreElements())
{
final URL url = enumeration.nextElement();
final InputStream is = url.openStream();
BufferedReader reader = null;
try
{
reader = new BufferedReader(new InputStreamReader(is, "UTF-8"));
String line = reader.readLine();
while (null != line)
{
final int comment = line.indexOf('#');
if (comment > -1)
{
line = line.substring(0, comment);
}
line = line.trim();
if (line.length() > 0)
{
try
{
providers.add(
loader.loadClass(line)
.asSubclass(serviceClass));
}
catch (ClassCastException e)
{
throw new IllegalStateException("Service " + line + " does not implement expected type "
+ serviceClass.getName());
}
}
line = reader.readLine();
}
}
finally
{
if (reader != null)
{
reader.close();
}
}
}
}
catch (Exception e)
{
throw new RuntimeException("Could not load services for " + serviceClass.getName(), e);
}
return providers;
}
/**
* Create a new instance of the found Service. <br/>
*
* Verifies that the found ServiceImpl implements Service.
*
* @param <T>
* @param serviceType The Service interface
* @param className The name of the implementation class
* @param loader The ClassLoader to load the ServiceImpl from
* @return A new instance of the ServiceImpl
* @throws Exception If problems creating a new instance
*/
private <T> T createInstance(Class<? extends T> serviceImplClass)
{
try
{
Constructor<? extends T> constructor = SecurityActions.getConstructor(serviceImplClass);
if (!constructor.isAccessible())
{
constructor.setAccessible(true);
}
return constructor.newInstance();
}
catch (Exception e)
{
throw new RuntimeException("Could not create a new instance of Service implementation " + serviceImplClass.getName(), e);
}
}
private <T> Set<T> createInstances(Class<T> serviceType, Set<Class<? extends T>> providers)
{
Set<T> providerImpls = new LinkedHashSet<T>();
for(Class<? extends T> serviceClass: providers)
{
providerImpls.add(createInstance(serviceClass));
}
return providerImpls;
}
}