// Copyright 2004, 2005 The Apache Software Foundation
//
// 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.apache.tapestry.services.impl;
import java.util.Locale;
import org.apache.hivemind.ApplicationRuntimeException;
import org.apache.hivemind.ClassResolver;
import org.apache.tapestry.IEngine;
import org.apache.tapestry.services.EngineFactory;
import org.apache.tapestry.spec.IApplicationSpecification;
/**
* Standard implementation of {@link org.apache.tapestry.services.EngineFactory} service.
* This should do for most purposes, since a major focus of Tapestry 4.0 is to no longer
* require subclassing of {@link org.apache.tapestry.engine.BaseEngine}.
*
* @author Howard Lewis Ship
* @since 4.0
*/
public class EngineFactoryImpl implements EngineFactory
{
private IApplicationSpecification _applicationSpecification;
private String _defaultEngineClassName;
private EngineConstructor _constructor;
private ClassResolver _classResolver;
interface EngineConstructor
{
IEngine construct();
}
// TODO: Create a BaseEngineConstructor that is hardcoded to
// instantiate a BaseEngine instance, without using reflection
// (for efficiency).
static class ReflectiveEngineConstructor implements EngineConstructor
{
private Class _engineClass;
ReflectiveEngineConstructor(Class engineClass)
{
_engineClass = engineClass;
}
public IEngine construct()
{
try
{
return (IEngine) _engineClass.newInstance();
}
catch (Exception ex)
{
throw new ApplicationRuntimeException(
ImplMessages.errorInstantiatingEngine(_engineClass, ex),
ex);
}
}
}
public void initializeService()
{
String engineClassName = _applicationSpecification.getEngineClassName();
// TODO: Check in web.xml first.
if (engineClassName == null)
engineClassName = _defaultEngineClassName;
Class engineClass = _classResolver.findClass(engineClassName);
_constructor = new ReflectiveEngineConstructor(engineClass);
}
public IEngine constructNewEngineInstance(Locale locale)
{
IEngine result = _constructor.construct();
result.setLocale(locale);
return result;
}
public void setApplicationSpecification(IApplicationSpecification specification)
{
_applicationSpecification = specification;
}
public void setClassResolver(ClassResolver resolver)
{
_classResolver = resolver;
}
public void setDefaultEngineClassName(String string)
{
_defaultEngineClassName = string;
}
}