beandefinition.java

spring api 源代码

/*
 * 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.config;

import org.springframework.beans.BeanMetadataElement;
import org.springframework.beans.MutablePropertyValues;
import org.springframework.core.AttributeAccessor;

/**
 * A BeanDefinition describes a bean instance, which has property values,
 * constructor argument values, and further information supplied by
 * concrete implementations.
 *
 * <p>This is just a minimal interface: The main intention is to allow a
 * {@link BeanFactoryPostProcessor} such as {@link PropertyPlaceholderConfigurer}
 * to introspect and modify property values and other bean metadata.
 *
 * @author Juergen Hoeller
 * @author Rob Harrop
 * @since 19.03.2004
 * @see ConfigurableListableBeanFactory#getBeanDefinition
 * @see org.springframework.beans.factory.support.RootBeanDefinition
 * @see org.springframework.beans.factory.support.ChildBeanDefinition
 */
public interface BeanDefinition extends AttributeAccessor, BeanMetadataElement {

	/**
	 * Scope identifier for the standard singleton scope: "singleton".
	 * <p>Note that extended bean factories might support further scopes.
	 * @see #setScope
	 */
	String SCOPE_SINGLETON = ConfigurableBeanFactory.SCOPE_SINGLETON;

	/**
	 * Scope identifier for the standard prototype scope: "prototype".
	 * <p>Note that extended bean factories might support further scopes.
	 * @see #setScope
	 */
	String SCOPE_PROTOTYPE = ConfigurableBeanFactory.SCOPE_PROTOTYPE;


	/**
	 * Role hint indicating that a <code>BeanDefinition</code> is a major part
	 * of the application. Typically corresponds to a user-defined bean.
	 */
	int ROLE_APPLICATION = 0;

	/**
	 * Role hint indicating that a <code>BeanDefinition</code> is a supporting
	 * part of some larger configuration, typically an outer
	 * {@link org.springframework.beans.factory.parsing.ComponentDefinition}.
	 * <code>SUPPORT</code> beans are considered important enough to be aware
	 * of when looking more closely at a particular
	 * {@link org.springframework.beans.factory.parsing.ComponentDefinition}, but
	 * not when looking at the overall configuration of an application.
	 */
	int ROLE_SUPPORT = 1;

	/**
	 * Role hint indicating that a <code>BeanDefinition</code> is providing
	 * an entirely background role and has no relevance to the end-user. This
	 * hint is used when registering beans that are completely part of the internal
	 * workings of a {@link org.springframework.beans.factory.parsing.ComponentDefinition}.
	 */
	int ROLE_INFRASTRUCTURE = 2;


	/**
	 * Return the current bean class name of this bean definition.
	 * <p>Note that this does not have to be the actual class name used at runtime,
	 * in case of a child definition overriding/inheriting the class name from its parent.
	 * Hence, do <i>not</i> consider this to be the definitive bean type at runtime but
	 * rather only use it for parsing purposes at the individual bean definition level.
	 */
	String getBeanClassName();

	/**
	 * Override the bean class name of this bean definition.
	 * <p>The class name can be modified during bean factory post-processing,
	 * typically replacing the original class name with a parsed variant of it.
	 */
	void setBeanClassName(String beanClassName);

	/**
	 * Return the constructor argument values for this bean.
	 * <p>The returned instance can be modified during bean factory post-processing.
	 * @return the ConstructorArgumentValues object (never <code>null</code>)
	 */
	ConstructorArgumentValues getConstructorArgumentValues();

	/**
	 * Return the property values to be applied to a new instance of the bean.
	 * <p>The returned instance can be modified during bean factory post-processing.
	 * @return the MutablePropertyValues object (never <code>null</code>)
	 */
	MutablePropertyValues getPropertyValues();


	/**
	 * Return the name of the current target scope for this bean.
	 */
	String getScope();

	/**
	 * Override the target scope of this bean, specifying a new scope name.
	 * @see #SCOPE_SINGLETON
	 * @see #SCOPE_PROTOTYPE
	 */
	void setScope(String scope);

	/**
	 * Return whether this a <b>Singleton</b>, with a single, shared instance
	 * returned on all calls.
	 */
	boolean isSingleton();

	/**
	 * Return whether this bean is "abstract", that is, not meant to be instantiated.
	 */
	boolean isAbstract();

	/**
	 * Return whether this bean should be lazily initialized, that is, not
	 * eagerly instantiated on startup.
	 */
	boolean isLazyInit();


	/**
	 * Return a description of the resource that this bean definition
	 * came from (for the purpose of showing context in case of errors).
	 */
	String getResourceDescription();

	/**
	 * Get the role hint for this <code>BeanDefinition</code>. The role hint
	 * provides tools with an indication of the importance of a particular
	 * <code>BeanDefinition</code>.
	 * @see #ROLE_APPLICATION
	 * @see #ROLE_INFRASTRUCTURE
	 * @see #ROLE_SUPPORT
	 */
	int getRole();

}