infra.beans.factory.xml.NamespaceHandler Maven / Gradle / Ivy
/*
* Copyright 2017 - 2024 the original author or authors.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see [https://www.gnu.org/licenses/]
*/
package infra.beans.factory.xml;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import infra.beans.factory.BeanFactory;
import infra.beans.factory.config.BeanDefinition;
import infra.beans.factory.config.BeanDefinitionHolder;
import infra.beans.factory.support.BeanDefinitionRegistry;
import infra.lang.Nullable;
/**
* Base interface used by the {@link DefaultBeanDefinitionDocumentReader}
* for handling custom namespaces in a Framework XML configuration file.
*
* Implementations are expected to return implementations of the
* {@link BeanDefinitionParser} interface for custom top-level tags and
* implementations of the {@link BeanDefinitionDecorator} interface for
* custom nested tags.
*
*
The parser will call {@link #parse} when it encounters a custom tag
* directly under the {@code } tags and {@link #decorate} when
* it encounters a custom tag directly under a {@code } tag.
*
* Developers writing their own custom element extensions typically will
* not implement this interface directly, but rather make use of the provided
* {@link NamespaceHandlerSupport} class.
*
* @author Rob Harrop
* @author Erik Wiersma
* @see DefaultBeanDefinitionDocumentReader
* @see NamespaceHandlerResolver
* @since 4.0
*/
public interface NamespaceHandler {
/**
* Invoked by the {@link DefaultBeanDefinitionDocumentReader} after
* construction but before any custom elements are parsed.
*
* @see NamespaceHandlerSupport#registerBeanDefinitionParser(String, BeanDefinitionParser)
*/
default void init() { }
/**
* Parse the specified {@link Element} and register any resulting
* {@link BeanDefinition BeanDefinitions} with the
* {@link BeanDefinitionRegistry}
* that is embedded in the supplied {@link ParserContext}.
*
Implementations should return the primary {@code BeanDefinition}
* that results from the parse phase if they wish to be used nested
* inside (for example) a {@code } tag.
* Implementations may return {@code null} if they will
* not be used in a nested scenario.
*
* @param element the element that is to be parsed into one or more {@code BeanDefinitions}
* @param parserContext the object encapsulating the current state of the parsing process
* @return the primary {@code BeanDefinition} (can be {@code null} as explained above)
*/
@Nullable
BeanDefinition parse(Element element, ParserContext parserContext);
/**
* Parse the specified {@link Node} and decorate the supplied
* {@link BeanDefinition}, returning the decorated definition.
*
The {@link Node} may be either an {@link org.w3c.dom.Attr} or an
* {@link Element}, depending on whether a custom attribute or element
* is being parsed.
*
Implementations may choose to return a completely new definition,
* which will replace the original definition in the resulting
* {@link BeanFactory}.
*
The supplied {@link ParserContext} can be used to register any
* additional beans needed to support the main definition.
*
* @param source the source element or attribute that is to be parsed
* @param definition the current bean definition
* @param parserContext the object encapsulating the current state of the parsing process
* @return the decorated definition (to be registered in the BeanFactory),
* or simply the original bean definition if no decoration is required.
* A {@code null} value is strictly speaking invalid, but will be leniently
* treated like the case where the original bean definition gets returned.
*/
@Nullable
BeanDefinitionHolder decorate(Node source, BeanDefinitionHolder definition, ParserContext parserContext);
}