SystemParamsUtils.java

/*
*
* Copyright 2005 AgileTec s.r.l. (http://www.agiletec.it) All rights reserved.
*
* This file is part of jAPS software.
* jAPS is a free software; 
* you can redistribute it and/or modify it
* under the terms of the GNU General Public License (GPL) as published by the Free Software Foundation; version 2.
* 
* See the file License for the specific language governing permissions   
* and limitations under the License
* 
* 
* 
* Copyright 2005 AgileTec s.r.l. (http://www.agiletec.it) All rights reserved.
*
*/
package com.agiletec.apsadmin.admin;

import java.io.StringReader;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.jdom.Document;
import org.jdom.Element;
import org.jdom.input.SAXBuilder;
import org.jdom.output.XMLOutputter;

import com.agiletec.aps.system.ApsSystemUtils;
import com.agiletec.aps.system.exception.ApsSystemException;

/**
 * DOM support class used to handle the configuration parameters.
 * @author E.Santoboni
 */
public class SystemParamsUtils {
	
	/**
	 * Return the configuration params contained in the given XML.
	 * @param xmlParams XML string containing the parameters to fetch.
	 * @return The resulting parameters map.
	 * @throws Throwable if errors are detected.
	 */
	public static Map<String, String> getParams(String xmlParams) throws Throwable {
		Map<String, String> params = new HashMap<String, String>();
		Document doc = decodeDOM(xmlParams);
		Element element = doc.getRootElement();
		insertParams(element, params);
		return params;
	}
	
	private static void insertParams(Element currentElement, Map<String, String> params) {
		if ("Param".equals(currentElement.getName())) {
			String key = currentElement.getAttributeValue("name");
			String value = currentElement.getText();
			params.put(key, value);
		}
		List<Element> elements = currentElement.getChildren();
		for (int i=0; i<elements.size(); i++) {
			Element element = elements.get(i);
			insertParams(element, params);
		}
	}
	
	/**
	 * Return the XML of the configuration with updated parameters.
	 * NOTE: All the values contained in the map but NOT in the given XML are ignored. 
	 * @param oldXmlParams The old configuration XML.
	 * @param newSystemParams The map with updated values
	 * @return String The new system configuration string.
	 * @throws Throwable if errors are detected.
	 */
	public static String getNewXmlParams(String oldXmlParams, Map<String, String> newSystemParams) throws Throwable {
		Document doc = decodeDOM(oldXmlParams);
		Element element = doc.getRootElement();
		Iterator<String> newParamsName = newSystemParams.keySet().iterator();
		while (newParamsName.hasNext()) {
			String paramName = (String) newParamsName.next();
			Element paramElement = searchParamElement(element, paramName);
			if (null != paramElement) {
				String value = newSystemParams.get(paramName);
				paramElement.setText(value);
			}
		}
		return getXMLDocument(doc);
	}
	
	public static String getXMLDocument(Document doc) {
		XMLOutputter out = new XMLOutputter();
		String xml = out.outputString(doc);
		return xml;
	}
	
	private static Element searchParamElement(Element currentElement, String paramName) {
		String elementName = currentElement.getName();
		String key = currentElement.getAttributeValue("name");
		if ("Param".equals(elementName) && paramName.equals(key)) {
			return currentElement;
		} else {
			List<Element> elements = currentElement.getChildren();
			for (int i=0; i<elements.size(); i++) {
				Element element = elements.get(i);
				Element result = searchParamElement(element, paramName);
				if (null != result) return result; 
			}
		}
		return null;
	}
	
	private static Document decodeDOM(String xmlText) throws ApsSystemException {
		SAXBuilder builder = new SAXBuilder();
		builder.setValidation(false);
		StringReader reader = new StringReader(xmlText);
		Document doc = null;
		try {
			doc = builder.build(reader);
		} catch (Throwable t) {
			ApsSystemUtils.getLogger().severe("Errore nel parsing: " + t.getMessage());
			throw new ApsSystemException("Errore nell'interpretazione dell'xml", t);
		}
		return doc;
	}
	
}