/*
* Copyright 2002-2008 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.context.support;
import java.io.IOException;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.support.DefaultListableBeanFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextException;
/**
* Base class for {@link org.springframework.context.ApplicationContext}
* implementations which are supposed to support multiple refreshs,
* creating a new internal bean factory instance every time.
* Typically (but not necessarily), such a context will be driven by
* a set of config locations to load bean definitions from.
*
* <p>The only method to be implemented by subclasses is {@link #loadBeanDefinitions},
* which gets invoked on each refresh. A concrete implementation is supposed to load
* bean definitions into the given
* {@link org.springframework.beans.factory.support.DefaultListableBeanFactory},
* typically delegating to one or more specific bean definition readers.
*
* <p><b>Note that there is a similar base class for WebApplicationContexts.</b>
* {@link org.springframework.web.context.support.AbstractRefreshableWebApplicationContext}
* provides the same subclassing strategy, but additionally pre-implements
* all context functionality for web environments. There is also a
* pre-defined way to receive config locations for a web context.
*
* <p>Concrete standalone subclasses of this base class, reading in a
* specific bean definition format, are {@link ClassPathXmlApplicationContext}
* and {@link FileSystemXmlApplicationContext}, which both derive from the
* common {@link AbstractXmlApplicationContext} base class.
*
* @author Juergen Hoeller
* @since 1.1.3
* @see #loadBeanDefinitions
* @see org.springframework.beans.factory.support.DefaultListableBeanFactory
* @see org.springframework.web.context.support.AbstractRefreshableWebApplicationContext
* @see AbstractXmlApplicationContext
* @see ClassPathXmlApplicationContext
* @see FileSystemXmlApplicationContext
*/
public abstract class AbstractRefreshableApplicationContext extends AbstractApplicationContext {
private Boolean allowBeanDefinitionOverriding;
private Boolean allowCircularReferences;
/** Bean factory for this context */
private DefaultListableBeanFactory beanFactory;
/** Synchronization monitor for the internal BeanFactory */
private final Object beanFactoryMonitor = new Object();
/**
* Create a new AbstractRefreshableApplicationContext with no parent.
*/
public AbstractRefreshableApplicationContext() {
}
/**
* Create a new AbstractRefreshableApplicationContext with the given parent context.
* @param parent the parent context
*/
public AbstractRefreshableApplicationContext(ApplicationContext parent) {
super(parent);
}
/**
* Set whether it should be allowed to override bean definitions by registering
* a different definition with the same name, automatically replacing the former.
* If not, an exception will be thrown. Default is "true".
* @see org.springframework.beans.factory.support.DefaultListableBeanFactory#setAllowBeanDefinitionOverriding
*/
public void setAllowBeanDefinitionOverriding(boolean allowBeanDefinitionOverriding) {
this.allowBeanDefinitionOverriding = Boolean.valueOf(allowBeanDefinitionOverriding);
}
/**
* Set whether to allow circular references between beans - and automatically
* try to resolve them.
* <p>Default is "true". Turn this off to throw an exception when encountering
* a circular reference, disallowing them completely.
* @see org.springframework.beans.factory.support.DefaultListableBeanFactory#setAllowCircularReferences
*/
public void setAllowCircularReferences(boolean allowCircularReferences) {
this.allowCircularReferences = Boolean.valueOf(allowCircularReferences);
}
/**
* This implementation performs an actual refresh of this context's underlying
* bean factory, shutting down the previous bean factory (if any) and
* initializing a fresh bean factory for the next phase of the context's lifecycle.
*/
protected final void refreshBeanFactory() throws BeansException {
if (hasBeanFactory()) {
destroyBeans();
closeBeanFactory();
}
try {
DefaultListableBeanFactory beanFactory = createBeanFactory();
customizeBeanFactory(beanFactory);
loadBeanDefinitions(beanFactory);
synchronized (this.beanFactoryMonitor) {
this.beanFactory = beanFactory;
}
}
catch (IOException ex) {
throw new ApplicationContextException(
"I/O error parsing XML document for application context [" + getDisplayName() + "]", ex);
}
}
protected final void closeBeanFactory() {
synchronized (this.beanFactoryMonitor) {
this.beanFactory = null;
}
}
/**
* Determine whether this context currently holds a bean factory,
* i.e. has been refreshed at least once and not been closed yet.
*/
protected final boolean hasBeanFactory() {
synchronized (this.beanFactoryMonitor) {
return (this.beanFactory != null);
}
}
public final ConfigurableListableBeanFactory getBeanFactory() {
synchronized (this.beanFactoryMonitor) {
if (this.beanFactory == null) {
throw new IllegalStateException("BeanFactory not initialized or already closed - " +
"call 'refresh' before accessing beans via the ApplicationContext");
}
return this.beanFactory;
}
}
/**
* Create an internal bean factory for this context.
* Called for each {@link #refresh()} attempt.
* <p>The default implementation creates a
* {@link org.springframework.beans.factory.support.DefaultListableBeanFactory}
* with the {@link #getInternalParentBeanFactory() internal bean factory} of this
* context's parent as parent bean factory. Can be overridden in subclasses,
* for example to customize DefaultListableBeanFactory's settings.
* @return the bean factory for this context
* @see org.springframework.beans.factory.support.DefaultListableBeanFactory#setAllowBeanDefinitionOverriding
* @see org.springframework.beans.factory.support.DefaultListableBeanFactory#setAllowEagerClassLoading
* @see org.springframework.beans.factory.support.DefaultListableBeanFactory#setAllowCircularReferences
* @see org.springframework.beans.factory.support.DefaultListableBeanFactory#setAllowRawInjectionDespiteWrapping
*/
protected DefaultListableBeanFactory createBeanFactory() {
return new DefaultListableBeanFactory(getInternalParentBeanFactory());
}
/**
* Customize the internal bean factory used by this context.
* Called for each {@link #refresh()} attempt.
* <p>The default implementation applies this context's
* {@link #setAllowBeanDefinitionOverriding "allowBeanDefinitionOverriding"}
* and {@link #setAllowCircularReferences "allowCircularReferences"} settings,
* if specified. Can be overridden in subclasses to customize any of
* {@link DefaultListableBeanFactory}'s settings.
* @param beanFactory the newly created bean factory for this context
* @see DefaultListableBeanFactory#setAllowBeanDefinitionOverriding
* @see DefaultListableBeanFactory#setAllowCircularReferences
* @see DefaultListableBeanFactory#setAllowRawInjectionDespiteWrapping
* @see DefaultListableBeanFactory#setAllowEagerClassLoading
*/
protected void customizeBeanFactory(DefaultListableBeanFactory beanFactory) {
if (this.allowBeanDefinitionOverriding != null) {
beanFactory.setAllowBeanDefinitionOverriding(this.allowBeanDefinitionOverriding.booleanValue());
}
if (this.allowCircularReferences != null) {
beanFactory.setAllowCircularReferences(this.allowCircularReferences.booleanValue());
}
}
/**
* Load bean definitions into the given bean factory, typically through
* delegating to one or more bean definition readers.
* @param beanFactory the bean factory to load bean definitions into
* @throws IOException if loading of bean definition files failed
* @throws BeansException if parsing of the bean definitions failed
* @see org.springframework.beans.factory.support.PropertiesBeanDefinitionReader
* @see org.springframework.beans.factory.xml.XmlBeanDefinitionReader
*/
protected abstract void loadBeanDefinitions(DefaultListableBeanFactory beanFactory)
throws IOException, BeansException;
}