https://github.com/spring-projects/spring-framework: Spring Beans (Spring IO)
  • Juergen Hoeller 
/*
 * Copyright 2002-2017 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.xml;

import org.w3c.dom.Element;

import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.support.AbstractBeanDefinition;
import org.springframework.beans.factory.support.BeanDefinitionBuilder;
import org.springframework.lang.Nullable;


Base class for those BeanDefinitionParser implementations that need to parse and define just a single BeanDefinition. 
Extend this parser class when you want to create a single bean definition from an arbitrarily complex XML element. You may wish to consider extending the AbstractSimpleBeanDefinitionParser when you want to create a single bean definition from a relatively simple custom XML element. 
The resulting BeanDefinition will be automatically registered with the BeanDefinitionRegistry. Your job simply is to parse the custom XML Element into a single BeanDefinition. 
Author:Rob Harrop, Juergen Hoeller, Rick Evans
See Also:
Since:2.0
/**
 * Base class for those {@link BeanDefinitionParser} implementations that
 * need to parse and define just a <i>single</i> {@code BeanDefinition}.
 *
 * <p>Extend this parser class when you want to create a single bean definition
 * from an arbitrarily complex XML element. You may wish to consider extending
 * the {@link AbstractSimpleBeanDefinitionParser} when you want to create a
 * single bean definition from a relatively simple custom XML element.
 *
 * <p>The resulting {@code BeanDefinition} will be automatically registered
 * with the {@link org.springframework.beans.factory.support.BeanDefinitionRegistry}.
 * Your job simply is to {@link #doParse parse} the custom XML {@link Element}
 * into a single {@code BeanDefinition}.
 *
 * @author Rob Harrop
 * @author Juergen Hoeller
 * @author Rick Evans
 * @since 2.0
 * @see #getBeanClass
 * @see #getBeanClassName
 * @see #doParse
 */
public abstract class AbstractSingleBeanDefinitionParser extends AbstractBeanDefinitionParser {

	
Creates a BeanDefinitionBuilder instance for the bean Class and passes it to the doParse strategy method. 
Params:
  • element – the element that is to be parsed into a single BeanDefinition
  • parserContext – the object encapsulating the current state of the parsing process
Throws:
See Also:
Returns:the BeanDefinition resulting from the parsing of the supplied Element
/**
	 * Creates a {@link BeanDefinitionBuilder} instance for the
	 * {@link #getBeanClass bean Class} and passes it to the
	 * {@link #doParse} strategy method.
	 * @param element the element that is to be parsed into a single BeanDefinition
	 * @param parserContext the object encapsulating the current state of the parsing process
	 * @return the BeanDefinition resulting from the parsing of the supplied {@link Element}
	 * @throws IllegalStateException if the bean {@link Class} returned from
	 * {@link #getBeanClass(org.w3c.dom.Element)} is {@code null}
	 * @see #doParse
	 */
	@Override
	protected final AbstractBeanDefinition parseInternal(Element element, ParserContext parserContext) {
		BeanDefinitionBuilder builder = BeanDefinitionBuilder.genericBeanDefinition();
		String parentName = getParentName(element);
		if (parentName != null) {
			builder.getRawBeanDefinition().setParentName(parentName);
		}
		Class<?> beanClass = getBeanClass(element);
		if (beanClass != null) {
			builder.getRawBeanDefinition().setBeanClass(beanClass);
		}
		else {
			String beanClassName = getBeanClassName(element);
			if (beanClassName != null) {
				builder.getRawBeanDefinition().setBeanClassName(beanClassName);
			}
		}
		builder.getRawBeanDefinition().setSource(parserContext.extractSource(element));
		BeanDefinition containingBd = parserContext.getContainingBeanDefinition();
		if (containingBd != null) {
			// Inner bean definition must receive same scope as containing bean.
			builder.setScope(containingBd.getScope());
		}
		if (parserContext.isDefaultLazyInit()) {
			// Default-lazy-init applies to custom bean definitions as well.
			builder.setLazyInit(true);
		}
		doParse(element, parserContext, builder);
		return builder.getBeanDefinition();
	}

	
Determine the name for the parent of the currently parsed bean,
in case of the current bean being defined as a child bean.

The default implementation returns null, indicating a root bean definition. 
Params:
  • element – the Element that is being parsed
Returns:the name of the parent bean for the currently parsed bean, or null if none
/**
	 * Determine the name for the parent of the currently parsed bean,
	 * in case of the current bean being defined as a child bean.
	 * <p>The default implementation returns {@code null},
	 * indicating a root bean definition.
	 * @param element the {@code Element} that is being parsed
	 * @return the name of the parent bean for the currently parsed bean,
	 * or {@code null} if none
	 */
	@Nullable
	protected String getParentName(Element element) {
		return null;
	}

	
Determine the bean class corresponding to the supplied Element. 
Note that, for application classes, it is generally preferable to override getBeanClassName instead, in order to avoid a direct dependence on the bean implementation class. The BeanDefinitionParser and its NamespaceHandler can be used within an IDE plugin then, even if the application classes are not available on the plugin's classpath. 
Params:
  • element – the Element that is being parsed
See Also:
Returns:the Class of the bean that is being defined via parsing the supplied Element, or null if none
/**
	 * Determine the bean class corresponding to the supplied {@link Element}.
	 * <p>Note that, for application classes, it is generally preferable to
	 * override {@link #getBeanClassName} instead, in order to avoid a direct
	 * dependence on the bean implementation class. The BeanDefinitionParser
	 * and its NamespaceHandler can be used within an IDE plugin then, even
	 * if the application classes are not available on the plugin's classpath.
	 * @param element the {@code Element} that is being parsed
	 * @return the {@link Class} of the bean that is being defined via parsing
	 * the supplied {@code Element}, or {@code null} if none
	 * @see #getBeanClassName
	 */
	@Nullable
	protected Class<?> getBeanClass(Element element) {
		return null;
	}

	
Determine the bean class name corresponding to the supplied Element. 
Params:
  • element – the Element that is being parsed
See Also:
Returns:the class name of the bean that is being defined via parsing the supplied Element, or null if none
/**
	 * Determine the bean class name corresponding to the supplied {@link Element}.
	 * @param element the {@code Element} that is being parsed
	 * @return the class name of the bean that is being defined via parsing
	 * the supplied {@code Element}, or {@code null} if none
	 * @see #getBeanClass
	 */
	@Nullable
	protected String getBeanClassName(Element element) {
		return null;
	}

	
Parse the supplied Element and populate the supplied BeanDefinitionBuilder as required. 
The default implementation delegates to the doParse version without ParserContext argument. 
Params:
  • element – the XML element being parsed
  • parserContext – the object encapsulating the current state of the parsing process
  • builder – used to define the BeanDefinition
See Also:
/**
	 * Parse the supplied {@link Element} and populate the supplied
	 * {@link BeanDefinitionBuilder} as required.
	 * <p>The default implementation delegates to the {@code doParse}
	 * version without ParserContext argument.
	 * @param element the XML element being parsed
	 * @param parserContext the object encapsulating the current state of the parsing process
	 * @param builder used to define the {@code BeanDefinition}
	 * @see #doParse(Element, BeanDefinitionBuilder)
	 */
	protected void doParse(Element element, ParserContext parserContext, BeanDefinitionBuilder builder) {
		doParse(element, builder);
	}

	
Parse the supplied Element and populate the supplied BeanDefinitionBuilder as required. 
The default implementation does nothing.

Params:
  • element – the XML element being parsed
  • builder – used to define the BeanDefinition
/**
	 * Parse the supplied {@link Element} and populate the supplied
	 * {@link BeanDefinitionBuilder} as required.
	 * <p>The default implementation does nothing.
	 * @param element the XML element being parsed
	 * @param builder used to define the {@code BeanDefinition}
	 */
	protected void doParse(Element element, BeanDefinitionBuilder builder) {
	}

}