nz.co.senanque.madura.configuration.XMLBeanFactory Maven / Gradle / Ivy

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Connects Apache Commons Configuration with Spring Beans. Useful for injecting configuration information into Spring Beans from an external configuration file.
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/*******************************************************************************
 * Copyright (c)2013 Prometheus Consulting
 *
 * 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 nz.co.senanque.madura.configuration;

import java.io.FileInputStream;
import java.io.InputStream;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.commons.configuration.beanutils.BeanDeclaration;
import org.apache.commons.configuration.beanutils.DefaultBeanFactory;
import org.apache.commons.configuration.beanutils.XMLBeanDeclaration;
import org.apache.commons.configuration.tree.ConfigurationNode;
import org.jdom.Attribute;
import org.jdom.Document;
import org.jdom.Element;
import org.jdom.input.SAXBuilder;

/**
 * 
 * This is a factory for apache.commons.config.
 * You can configure it to return an XML document. It does not cache, but Spring does.
 * 

 * 
 *    <test1 config-class="org.jdom.Document"

 *           config-factory="nz.co.senanque.madura.configuration.XMLBeanFactory">

 *         <A>XYZ</A>

 *         <B>ABC</B>

 *     </test1>

 * 
 *  

 * 
 * @author Roger Parkinson
 * @version $Revision: 1.4 $
 */
public class XMLBeanFactory extends DefaultBeanFactory
{
    /** A map for the so far created instances.*/
    private Map beans;
    
    public XMLBeanFactory()
    {
        super();
        beans = new HashMap();
    }
    
    // Creates the bean. Checks if already an instance exists.
    public synchronized Object createBean(Class beanClass, BeanDeclaration decl,
        Object param) throws Exception
    {
        Map m = decl.getBeanProperties();
        XMLBeanDeclaration xmlDecl = (XMLBeanDeclaration)decl;
        ConfigurationNode n = xmlDecl.getNode();
        String nodeName = n.getName();
        n = n.getParentNode();
        while (n != null)
        {
            if (n.getName() != null)
                nodeName = n.getName()+"/"+nodeName;
            n = n.getParentNode();
        }
        Object bean = beans.get(nodeName);
        if (bean != null)
        {
            // Yes, there is already an instance
            return bean;
        }
        String fileLocation = (String)m.get("fileLocation");
        Document doc = null;
        SAXBuilder sax = new SAXBuilder();
        if (fileLocation == null)
        {
            // build the doc from the children
            ConfigurationNode node = xmlDecl.getNode();
            doc = new Document();
            doc.addContent(makeElement(node));
        }
        else
        {
            InputStream in = new FileInputStream(fileLocation);
            doc = sax.build(in);
        }
        bean = doc;
        // Store it in map
        beans.put(nodeName, bean);
        return bean;
    }

    private Element makeElement(ConfigurationNode node)
    {
        Element element = new Element(node.getName());
        Object value = node.getValue();
        if (value != null)
            element.setText(value.toString());
        List attributes = node.getAttributes();
        for (ConfigurationNode attribute: attributes)
        {
            element.setAttribute(new Attribute(attribute.getName(),attribute.getValue().toString()));
        }
        List children = node.getChildren();
        for (ConfigurationNode child: children)
        {
            element.addContent(makeElement(child));
        }
        return element;
    }
}