org.springframework.beans.factory.xml.NamespaceHandlerSupport Maven / Gradle / Ivy
/*
* 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
*
* https://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 java.util.HashMap;
import java.util.Map;
import org.w3c.dom.Attr;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.BeanDefinitionHolder;
import org.springframework.lang.Nullable;
/**
* Support class for implementing custom {@link NamespaceHandler NamespaceHandlers}.
* Parsing and decorating of individual {@link Node Nodes} is done via {@link BeanDefinitionParser}
* and {@link BeanDefinitionDecorator} strategy interfaces, respectively.
*
* Provides the {@link #registerBeanDefinitionParser} and {@link #registerBeanDefinitionDecorator}
* methods for registering a {@link BeanDefinitionParser} or {@link BeanDefinitionDecorator}
* to handle a specific element.
*
* @author Rob Harrop
* @author Juergen Hoeller
* @since 2.0
* @see #registerBeanDefinitionParser(String, BeanDefinitionParser)
* @see #registerBeanDefinitionDecorator(String, BeanDefinitionDecorator)
*/
public abstract class NamespaceHandlerSupport implements NamespaceHandler {
/**
* Stores the {@link BeanDefinitionParser} implementations keyed by the
* local name of the {@link Element Elements} they handle.
*/
private final Map parsers = new HashMap<>();
/**
* Stores the {@link BeanDefinitionDecorator} implementations keyed by the
* local name of the {@link Element Elements} they handle.
*/
private final Map decorators = new HashMap<>();
/**
* Stores the {@link BeanDefinitionDecorator} implementations keyed by the local
* name of the {@link Attr Attrs} they handle.
*/
private final Map attributeDecorators = new HashMap<>();
/**
* Parses the supplied {@link Element} by delegating to the {@link BeanDefinitionParser} that is
* registered for that {@link Element}.
*/
@Override
@Nullable
public BeanDefinition parse(Element element, ParserContext parserContext) {
BeanDefinitionParser parser = findParserForElement(element, parserContext);
return (parser != null ? parser.parse(element, parserContext) : null);
}
/**
* Locates the {@link BeanDefinitionParser} from the register implementations using
* the local name of the supplied {@link Element}.
*/
@Nullable
private BeanDefinitionParser findParserForElement(Element element, ParserContext parserContext) {
String localName = parserContext.getDelegate().getLocalName(element);
BeanDefinitionParser parser = this.parsers.get(localName);
if (parser == null) {
parserContext.getReaderContext().fatal(
"Cannot locate BeanDefinitionParser for element [" + localName + "]", element);
}
return parser;
}
/**
* Decorates the supplied {@link Node} by delegating to the {@link BeanDefinitionDecorator} that
* is registered to handle that {@link Node}.
*/
@Override
@Nullable
public BeanDefinitionHolder decorate(
Node node, BeanDefinitionHolder definition, ParserContext parserContext) {
BeanDefinitionDecorator decorator = findDecoratorForNode(node, parserContext);
return (decorator != null ? decorator.decorate(node, definition, parserContext) : null);
}
/**
* Locates the {@link BeanDefinitionParser} from the register implementations using
* the local name of the supplied {@link Node}. Supports both {@link Element Elements}
* and {@link Attr Attrs}.
*/
@Nullable
private BeanDefinitionDecorator findDecoratorForNode(Node node, ParserContext parserContext) {
BeanDefinitionDecorator decorator = null;
String localName = parserContext.getDelegate().getLocalName(node);
if (node instanceof Element) {
decorator = this.decorators.get(localName);
}
else if (node instanceof Attr) {
decorator = this.attributeDecorators.get(localName);
}
else {
parserContext.getReaderContext().fatal(
"Cannot decorate based on Nodes of type [" + node.getClass().getName() + "]", node);
}
if (decorator == null) {
parserContext.getReaderContext().fatal("Cannot locate BeanDefinitionDecorator for " +
(node instanceof Element ? "element" : "attribute") + " [" + localName + "]", node);
}
return decorator;
}
/**
* Subclasses can call this to register the supplied {@link BeanDefinitionParser} to
* handle the specified element. The element name is the local (non-namespace qualified)
* name.
*/
protected final void registerBeanDefinitionParser(String elementName, BeanDefinitionParser parser) {
this.parsers.put(elementName, parser);
}
/**
* Subclasses can call this to register the supplied {@link BeanDefinitionDecorator} to
* handle the specified element. The element name is the local (non-namespace qualified)
* name.
*/
protected final void registerBeanDefinitionDecorator(String elementName, BeanDefinitionDecorator dec) {
this.decorators.put(elementName, dec);
}
/**
* Subclasses can call this to register the supplied {@link BeanDefinitionDecorator} to
* handle the specified attribute. The attribute name is the local (non-namespace qualified)
* name.
*/
protected final void registerBeanDefinitionDecoratorForAttribute(String attrName, BeanDefinitionDecorator dec) {
this.attributeDecorators.put(attrName, dec);
}
}