com.alipay.sofa.runtime.ext.spring.parser.AbstractExtPointBeanDefinitionParser Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 com.alipay.sofa.runtime.ext.spring.parser;
import org.springframework.beans.factory.BeanDefinitionStoreException;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.BeanDefinitionHolder;
import org.springframework.beans.factory.parsing.BeanComponentDefinition;
import org.springframework.beans.factory.support.AbstractBeanDefinition;
import org.springframework.beans.factory.support.BeanDefinitionReaderUtils;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.beans.factory.xml.BeanDefinitionParser;
import org.springframework.beans.factory.xml.ParserContext;
import org.springframework.util.StringUtils;
import org.w3c.dom.Element;
/**
* Abstract parser for extension and extension point.
*
* @author fengqi.lin
* @since 2.6.0
*/
public abstract class AbstractExtPointBeanDefinitionParser implements BeanDefinitionParser {
/**
* Constant for the id attribute
*/
public static final String ID_ATTRIBUTE = "id";
@Override
public final BeanDefinition parse(Element element, ParserContext parserContext) {
AbstractBeanDefinition definition = parseInternal(element, parserContext);
if (definition != null && !parserContext.isNested()) {
try {
String id = resolveId(element, definition, parserContext);
if (!StringUtils.hasText(id)) {
parserContext.getReaderContext().error(
"Id is required for element '"
+ parserContext.getDelegate().getLocalName(element)
+ "' when used as a top-level tag", element);
}
BeanDefinitionHolder holder = new BeanDefinitionHolder(definition, id);
registerBeanDefinition(holder, parserContext.getRegistry());
if (shouldFireEvents()) {
BeanComponentDefinition componentDefinition = new BeanComponentDefinition(
holder);
postProcessComponentDefinition(componentDefinition);
parserContext.registerComponent(componentDefinition);
}
} catch (BeanDefinitionStoreException ex) {
parserContext.getReaderContext().error(ex.getMessage(), element);
return null;
}
}
return definition;
}
/**
* Resolve the ID for the supplied {@link BeanDefinition}.
* When using {@link #shouldGenerateId generation}, a name is generated automatically.
* Otherwise, the ID is extracted from the "id" attribute, potentially with a
* {@link #shouldGenerateIdAsFallback() fallback} to a generated id.
*
* @param element the element that the bean definition has been built from
* @param definition the bean definition to be registered
* @param parserContext the object encapsulating the current state of the parsing process;
* provides access to a {@link BeanDefinitionRegistry}
* @return the resolved id
* @throws BeanDefinitionStoreException if no unique name could be generated
* for the given bean definition
*/
protected String resolveId(Element element, AbstractBeanDefinition definition,
ParserContext parserContext) throws BeanDefinitionStoreException {
if (shouldGenerateId()) {
return parserContext.getReaderContext().generateBeanName(definition);
} else {
String id = element.getAttribute(ID_ATTRIBUTE);
if (!StringUtils.hasText(id) && shouldGenerateIdAsFallback()) {
id = parserContext.getReaderContext().generateBeanName(definition);
}
return id;
}
}
/**
* Register the supplied {@link BeanDefinitionHolder bean} with the supplied
* {@link BeanDefinitionRegistry registry}.
*
Subclasses can override this method to control whether or not the supplied
* {@link BeanDefinitionHolder bean} is actually even registered, or to
* register even more beans.
*
The default implementation registers the supplied {@link BeanDefinitionHolder bean}
* with the supplied {@link BeanDefinitionRegistry registry} only if the isNested
* parameter is false, because one typically does not want inner beans
* to be registered as top level beans.
*
* @param definition the bean definition to be registered
* @param registry the registry that the bean is to be registered with
* @see BeanDefinitionReaderUtils#registerBeanDefinition(BeanDefinitionHolder, BeanDefinitionRegistry)
*/
protected void registerBeanDefinition(BeanDefinitionHolder definition,
BeanDefinitionRegistry registry) {
BeanDefinitionReaderUtils.registerBeanDefinition(definition, registry);
}
/**
* Central template method to actually parse the supplied {@link Element}
* into one or more {@link BeanDefinition BeanDefinitions}.
*
* @param element the element that is to be parsed into one or more {@link BeanDefinition BeanDefinitions}
* @param parserContext the object encapsulating the current state of the parsing process;
* provides access to a {@link BeanDefinitionRegistry}
* @return the primary {@link BeanDefinition} resulting from the parsing of the supplied {@link Element}
* @see #parse(Element, ParserContext)
* @see #postProcessComponentDefinition(BeanComponentDefinition)
*/
protected abstract AbstractBeanDefinition parseInternal(Element element,
ParserContext parserContext);
/**
* Should an ID be generated instead of read from the passed in {@link Element}?
*
Disabled by default; subclasses can override this to enable ID generation.
* Note that this flag is about always generating an ID; the parser
* won't even check for an "id" attribute in this case.
*
* @return whether the parser should always generate an id
*/
protected boolean shouldGenerateId() {
return false;
}
/**
* Should an ID be generated instead if the passed in {@link Element} does not
* specify an "id" attribute explicitly?
*
Disabled by default; subclasses can override this to enable ID generation
* as fallback: The parser will first check for an "id" attribute in this case,
* only falling back to a generated ID if no value was specified.
*
* @return whether the parser should generate an id if no id was specified
*/
protected boolean shouldGenerateIdAsFallback() {
return false;
}
/**
* Controls whether this parser is supposed to fire a
* {@link BeanComponentDefinition}
* event after parsing the bean definition.
*
This implementation returns true by default; that is,
* an event will be fired when a bean definition has been completely parsed.
* Override this to return false in order to suppress the event.
*
* @return true in order to fire a component registration event
* after parsing the bean definition; false to suppress the event
* @see #postProcessComponentDefinition
* @see org.springframework.beans.factory.parsing.ReaderContext#fireComponentRegistered
*/
protected boolean shouldFireEvents() {
return true;
}
/**
* Hook method called after the primary parsing of a
* {@link BeanComponentDefinition} but before the
* {@link BeanComponentDefinition} has been registered with a
* {@link BeanDefinitionRegistry}.
*
Derived classes can override this method to supply any custom logic that
* is to be executed after all the parsing is finished.
*
The default implementation is a no-op.
*
* @param componentDefinition the {@link BeanComponentDefinition} that is to be processed
*/
protected void postProcessComponentDefinition(BeanComponentDefinition componentDefinition) {
}
}