com.ocpsoft.pretty.faces.el.LazyBeanNameFinder Maven / Gradle / Ivy
/*
* Copyright 2010 Lincoln Baxter, III
*
* 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 com.ocpsoft.pretty.faces.el;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import javax.servlet.ServletContext;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.ocpsoft.common.services.ServiceLoader;
import org.ocpsoft.rewrite.el.spi.BeanNameResolver;
/**
*
* Class implementing lazy resolving of bean names.
*
*
* This class is typically created once and is than supplied to {@link LazyExpression} instances in the
* {@link LazyExpression#LazyExpression(LazyBeanNameFinder, Class, String)} constructor.
*
*
* @author Christian Kaltepoth
*/
public class LazyBeanNameFinder
{
private final static Log log = LogFactory.getLog(LazyBeanNameFinder.class);
/**
* List of all resolvers. Initialized once on object creation
*/
private final List resolvers = new ArrayList();
/**
* Creates a new {@link LazyBeanNameFinder}. The constructor will find all implementations of
* {@link ELBeanNameResolver} by using the {@link ServiceLoader} mechanism.
*
* @param servletContext The servlet context
*/
public LazyBeanNameFinder(ServletContext servletContext)
{
// we use the context classloader
ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
// fallback, if no context classloader exists
if (classLoader == null)
{
classLoader = this.getClass().getClassLoader();
}
// find resolvers via ServiceLoader
@SuppressWarnings("unchecked")
Iterator beanNameFinderIterator = ServiceLoader.load(BeanNameResolver.class).iterator();
// call init() method on all resolvers
while (beanNameFinderIterator.hasNext())
{
// log resolver name
BeanNameResolver resolver = beanNameFinderIterator.next();
if (log.isTraceEnabled())
{
log.trace("Initializing BeanNameResolver: " + resolver.getClass().getName());
}
try
{
resolvers.add(resolver);
}
catch (ClassFormatError e)
{
/*
* Seems to happen for CDI classes when using GWT
* In this case just ignore the resolver
* See: http://code.google.com/p/prettyfaces/issues/detail?id=101
*/
log.warn("Failed to initialize " + resolver.getClass().getSimpleName() + ": " + e.getMessage());
}
}
}
/**
* Find the bean name of the supplied class. This method will try to resolve the bean name by calling all registered
* implementations of {@link ELBeanNameResolver}. This method will either return the resolved name or throw an
* {@link IllegalStateException}, if no resolver knows the name of the bean.
*
* @param clazz The class of the bean
* @return The resolved bean name
* @throws IllegalStateException If the name of the bean cannot be resolved
*/
public String findBeanName(Class clazz) throws IllegalStateException
{
// process all resolvers
for (BeanNameResolver resolver : resolvers)
{
// try to resolve bean name with current resolver
String name = resolver.getBeanName(clazz);
// return the bean name, if the resolver was successful
if (name != null)
{
return name;
}
}
// No resolver knows the name of the bean
throw new IllegalStateException("Cannot find name of bean '" + clazz.getName()
+ "'! You should place a @URLBeanName annotation on this class to let PrettyFaces know its name.");
}
}