/*
* Copyright 2004 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.
*
* $Header:$
*/
package org.apache.beehive.controls.spi.bean;
import java.io.InputStream;
import java.io.IOException;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.util.Properties;
import java.util.concurrent.ConcurrentHashMap;
import org.apache.beehive.controls.api.properties.PropertyMap;
import org.apache.beehive.controls.api.properties.BeanPropertyMap;
import org.apache.beehive.controls.api.properties.PropertyKey;
import org.apache.beehive.controls.api.bean.ControlBean;
import org.apache.beehive.controls.api.context.ControlBeanContext;
import org.apache.beehive.controls.api.ControlException;
/**
* The SimpleControlFactory class is a default implementation of the
* <code>org.apache.beehive.controls.api.bean.ControlFactory</code> interface. It
* uses Java reflection to create new control instances.
*
* @see org.apache.beehive.controls.api.bean.Controls#instantiate
* @see org.apache.beehive.controls.spi.bean.ControlFactory
*/
public class JavaControlFactory implements ControlFactory
{
private static ConcurrentHashMap<Class, Constructor> _constructors = new ConcurrentHashMap<Class, Constructor>();
private static final Properties _extImplBindings = new Properties();
private static final String EXT_IMPL_BINDING_CONFIG = "controlbindings.properties";
private static final String KEY_CONTROL_IMPLEMENTATION = "controlImplementation";
static
{
InputStream is = JavaControlFactory.class.getClassLoader().getResourceAsStream( EXT_IMPL_BINDING_CONFIG );
if ( is != null )
{
try
{
_extImplBindings.load( is );
}
catch(IOException ignore) { }
}
}
/**
* Instantiates a new ControlBean of the requested class, using mechanisms provided
* by a provider-specific JavaBeans framework.
*
* @param beanClass the ControlBean class to instantiate
* @param props an initial set of client-specified properties to associate with the
* bean instance. May be null.
* @param context the containing ControlBeanContext for the bean, if nested inside of
* a container or other control. May be null to use the current active
* execution context.
* @param id the bean control ID. Must be unique within the containing context. If
* null, a unique identifier will be auto-generated.
* @return a new ControlBean instance of the requested class.
*/
public <T extends ControlBean> T instantiate(Class<T> beanClass,
PropertyMap props,
ControlBeanContext context,
String id)
{
String beanClassName = beanClass.getName();
String extImplBinding = _extImplBindings.getProperty( beanClassName + "_" + id );
if ( extImplBinding == null )
extImplBinding = _extImplBindings.getProperty( beanClassName );
if ( extImplBinding != null )
{
BeanPropertyMap bpm = props == null ? new BeanPropertyMap( beanClass ) : new BeanPropertyMap( props );
PropertyKey propKey = new PropertyKey(org.apache.beehive.controls.api.properties.BaseProperties.class,
KEY_CONTROL_IMPLEMENTATION);
bpm.setProperty( propKey, extImplBinding );
props = bpm;
}
T ret = null;
try
{
Constructor<T> ctor = _constructors.get(beanClass);
if (ctor == null)
{
ctor = beanClass.getConstructor(ControlBeanContext.class,
String.class,
PropertyMap.class);
_constructors.put(beanClass, ctor);
}
ret = ctor.newInstance(context, id, props);
}
catch (InvocationTargetException ite)
{
Throwable t = ite.getCause();
throw new ControlException("ControlBean constructor exception", t);
}
catch (Exception e)
{
throw new ControlException("Exception creating ControlBean", e);
}
return ret;
}
}