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Spring Framework example source code file (AbstractSimpleBeanDefinitionParser.java)

This example Spring Framework source code file (AbstractSimpleBeanDefinitionParser.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Spring Framework tags/keywords

abstractsimplebeandefinitionparser, abstractsinglebeandefinitionparser, attr, attr, beandefinitionbuilder, dom, element, illegal, illegal, namednodemap, namednodemap, string, string

The Spring Framework AbstractSimpleBeanDefinitionParser.java source code

/*
 * 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.xml;

import org.w3c.dom.Attr;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;

import org.springframework.beans.factory.support.BeanDefinitionBuilder;
import org.springframework.core.Conventions;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;

/**
 * Convenient base class for when there exists a one-to-one mapping
 * between attribute names on the element that is to be parsed and
 * the property names on the {@link Class} being configured.
 *
 * <p>Extend this parser class when you want to create a single
 * bean definition from a relatively simple custom XML element. The
 * resulting <code>BeanDefinition will be automatically
 * registered with the relevant
 * {@link org.springframework.beans.factory.support.BeanDefinitionRegistry}.
 *
 * <p>An example will hopefully make the use of this particular parser
 * class immediately clear. Consider the following class definition:
 *
 * <pre class="code">public class SimpleCache implements Cache {
 * 
 *     public void setName(String name) {...}
 *     public void setTimeout(int timeout) {...}
 *     public void setEvictionPolicy(EvictionPolicy policy) {...}
 * 
 *     // remaining class definition elided for clarity...
 * }</pre>
 *
 * <p>Then let us assume the following XML tag has been defined to
 * permit the easy configuration of instances of the above class;
 *
 * <pre class="code"><caching:cache name="..." timeout="..." eviction-policy="..."/>
* * <p>All that is required of the Java developer tasked with writing * the parser to parse the above XML tag into an actual * <code>SimpleCache bean definition is the following: * * <pre class="code">public class SimpleCacheBeanDefinitionParser extends AbstractSimpleBeanDefinitionParser { * * protected Class getBeanClass(Element element) { * return SimpleCache.class; * } * }</pre> * * <p>Please note that the AbstractSimpleBeanDefinitionParser * is limited to populating the created bean definition with property values. * if you want to parse constructor arguments and nested elements from the * supplied XML element, then you will have to implement the * {@link #postProcess(org.springframework.beans.factory.support.BeanDefinitionBuilder, org.w3c.dom.Element)} * method and do such parsing yourself, or (more likely) subclass the * {@link AbstractSingleBeanDefinitionParser} or {@link AbstractBeanDefinitionParser} * classes directly. * * <p>The process of actually registering the * <code>SimpleCacheBeanDefinitionParser with the Spring XML parsing * infrastructure is described in the Spring Framework reference documentation * (in one of the appendices). * * <p>For an example of this parser in action (so to speak), do look at * the source code for the * {@link org.springframework.beans.factory.xml.UtilNamespaceHandler.PropertiesBeanDefinitionParser}; * the observant (and even not so observant) reader will immediately notice that * there is next to no code in the implementation. The * <code>PropertiesBeanDefinitionParser populates a * {@link org.springframework.beans.factory.config.PropertiesFactoryBean} * from an XML element that looks like this: * * <pre class="code"><util:properties location="jdbc.properties"/> * * <p>The observant reader will notice that the sole attribute on the * <code><util:properties/> element matches the * {@link org.springframework.beans.factory.config.PropertiesFactoryBean#setLocation(org.springframework.core.io.Resource)} * method name on the <code>PropertiesFactoryBean (the general * usage thus illustrated holds true for any number of attributes). * All that the <code>PropertiesBeanDefinitionParser needs * actually do is supply an implementation of the * {@link #getBeanClass(org.w3c.dom.Element)} method to return the * <code>PropertiesFactoryBean type. * * @author Rob Harrop * @author Rick Evans * @author Juergen Hoeller * @since 2.0 * @see Conventions#attributeNameToPropertyName(String) */ public abstract class AbstractSimpleBeanDefinitionParser extends AbstractSingleBeanDefinitionParser { /** * Parse the supplied {@link Element} and populate the supplied * {@link BeanDefinitionBuilder} as required. * <p>This implementation maps any attributes present on the * supplied element to {@link org.springframework.beans.PropertyValue} * instances, and * {@link BeanDefinitionBuilder#addPropertyValue(String, Object) adds them} * to the * {@link org.springframework.beans.factory.config.BeanDefinition builder}. * <p>The {@link #extractPropertyName(String)} method is used to * reconcile the name of an attribute with the name of a JavaBean * property. * @param element the XML element being parsed * @param builder used to define the <code>BeanDefinition * @see #extractPropertyName(String) */ protected final void doParse(Element element, BeanDefinitionBuilder builder) { NamedNodeMap attributes = element.getAttributes(); for (int x = 0; x < attributes.getLength(); x++) { Attr attribute = (Attr) attributes.item(x); if (isEligibleAttribute(attribute)) { String propertyName = extractPropertyName(attribute.getLocalName()); Assert.state(StringUtils.hasText(propertyName), "Illegal property name returned from 'extractPropertyName(String)': cannot be null or empty."); builder.addPropertyValue(propertyName, attribute.getValue()); } } postProcess(builder, element); } /** * Determine whether the given attribute is eligible for being * turned into a corresponding bean property value. * <p>The default implementation considers any attribute as eligible, * except for the "id" attribute and namespace declaration attributes. * @param attribute the XML attribute to check * @see #isEligibleAttribute(String) */ protected boolean isEligibleAttribute(Attr attribute) { String fullName = attribute.getName(); return (!fullName.equals("xmlns") && !fullName.startsWith("xmlns:") && isEligibleAttribute(attribute.getLocalName())); } /** * Determine whether the given attribute is eligible for being * turned into a corresponding bean property value. * <p>The default implementation considers any attribute as eligible, * except for the "id" attribute. * @param attributeName the attribute name taken straight from the * XML element being parsed (never <code>null) */ protected boolean isEligibleAttribute(String attributeName) { return !ID_ATTRIBUTE.equals(attributeName); } /** * Extract a JavaBean property name from the supplied attribute name. * <p>The default implementation uses the * {@link Conventions#attributeNameToPropertyName(String)} * method to perform the extraction. * <p>The name returned must obey the standard JavaBean property name * conventions. For example for a class with a setter method * '<code>setBingoHallFavourite(String)', the name returned had * better be '<code>bingoHallFavourite' (with that exact casing). * @param attributeName the attribute name taken straight from the * XML element being parsed (never <code>null) * @return the extracted JavaBean property name (must never be <code>null) */ protected String extractPropertyName(String attributeName) { return Conventions.attributeNameToPropertyName(attributeName); } /** * Hook method that derived classes can implement to inspect/change a * bean definition after parsing is complete. * <p>The default implementation does nothing. * @param beanDefinition the parsed (and probably totally defined) bean definition being built * @param element the XML element that was the source of the bean definition's metadata */ protected void postProcess(BeanDefinitionBuilder beanDefinition, Element element) { } }

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