/*
* Copyright 2002-2007 the original author or authors.
*
* 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.springframework.beans.factory.access;
import org.springframework.beans.BeansException;
/**
* Defines a contract for the lookup, use, and release of a
* {@link org.springframework.beans.factory.BeanFactory},
* or a <code>BeanFactory</code> subclass such as an
* {@link org.springframework.context.ApplicationContext}.
*
* <p>Where this interface is implemented as a singleton class such as
* {@link SingletonBeanFactoryLocator}, the Spring team <strong>strongly</strong>
* suggests that it be used sparingly and with caution. By far the vast majority
* of the code inside an application is best written in a Dependency Injection
* style, where that code is served out of a
* <code>BeanFactory</code>/<code>ApplicationContext</code> container, and has
* its own dependencies supplied by the container when it is created. However,
* even such a singleton implementation sometimes has its use in the small glue
* layers of code that is sometimes needed to tie other code together. For
* example, third party code may try to construct new objects directly, without
* the ability to force it to get these objects out of a <code>BeanFactory</code>.
* If the object constructed by the third party code is just a small stub or
* proxy, which then uses an implementation of this class to get a
* <code>BeanFactory</code> from which it gets the real object, to which it
* delegates, then proper Dependency Injection has been achieved.
*
* <p>As another example, in a complex J2EE app with multiple layers, with each
* layer having its own <code>ApplicationContext</code> definition (in a
* hierarchy), a class like <code>SingletonBeanFactoryLocator</code> may be used
* to demand load these contexts.
*
* @author Colin Sampaleanu
* @see org.springframework.beans.factory.BeanFactory
* @see org.springframework.context.access.DefaultLocatorFactory
* @see org.springframework.context.ApplicationContext
*/
public interface BeanFactoryLocator {
/**
* Use the {@link org.springframework.beans.factory.BeanFactory} (or derived
* interface such as {@link org.springframework.context.ApplicationContext})
* specified by the <code>factoryKey</code> parameter.
* <p>The definition is possibly loaded/created as needed.
* @param factoryKey a resource name specifying which <code>BeanFactory</code> the
* <code>BeanFactoryLocator</code> must return for usage. The actual meaning of the
* resource name is specific to the implementation of <code>BeanFactoryLocator</code>.
* @return the <code>BeanFactory</code> instance, wrapped as a {@link BeanFactoryReference} object
* @throws BeansException if there is an error loading or accessing the <code>BeanFactory</code>
*/
BeanFactoryReference useBeanFactory(String factoryKey) throws BeansException;
}