org.apache.commons.configuration.beanutils.BeanFactory Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.commons.configuration.beanutils;
/**
*
* Definition of an interface for bean factories.
*
*
* Beans defined in configuration files are not directly created, but by so
* called bean factories. This additional level of indirection
* provides for high flexibility in the creation process. For instance one
* implementation of this interface could be very simple and create a new
* instance of the specified class for each invocation. A different
* implementation could cache already created beans and ensure that always the
* same bean of the given class will be returned - this would be an easy mean
* for creating singleton objects.
*
*
* The interface itself is quite simple. There is a single method for creating a
* bean of a given class. All necessary parameters are obtained from an also
* passed in {@link BeanDeclaration} object. It is also possible
* (but optional) for a bean factory to declare the default class of the bean it
* creates. Then it is not necessary to specify a bean class in the bean
* declaration.
*
*
* @since 1.3
* @author Oliver Heger
* @version $Id: BeanFactory.java 439648 2006-09-02 20:42:10Z oheger $
*/
public interface BeanFactory
{
/**
* Returns a bean instance for the given class. The bean will be initialized
* from the specified bean declaration object. It is up to a concrete
* implementation how the bean will be created and initialized.
*
* @param beanClass the class for the bean
* @param data the bean declaration object containing all data about the
* bean to be created
* @param param an additional parameter that may be passed by calling code;
* it is up to a concrete implementation how this parameter is evaluated
* @return the new bean instance (should not be null)
* @throws Exception if an error occurs (the helper classes for creating
* beans will catch this unspecific exception and wrap it in a configuration
* exception)
*/
Object createBean(Class beanClass, BeanDeclaration data, Object param)
throws Exception;
/**
* Returns the default bean class of this bean factory. If an implementation
* here returns a non null value, bean declarations using this
* factory do not need to provide the name of the bean class. In such a case
* an instance of the default class will be created.
*
* @return the default class of this factory or null if there is
* none
*/
Class getDefaultBeanClass();
}