XMLExportType.java

/*
 * #%L
 * Lapis JSF Exporter - XML export type
 * %%
 * Copyright (C) 2013 - 2015 Lapis Software Associates
 * %%
 * 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.
 * #L%
 */
package com.lapis.jsfexporter.xml;

import javax.faces.context.ExternalContext;

import org.jdom2.Document;
import org.jdom2.Element;
import org.jdom2.output.Format;
import org.jdom2.output.XMLOutputter;

import com.lapis.jsfexporter.api.AbstractExportType;
import com.lapis.jsfexporter.api.IExportCell;
import com.lapis.jsfexporter.api.IExportRow;

public class XMLExportType extends AbstractExportType<Document, Void, Element> {

	// !|"|#|\$|%|&|'|\(|\)|\*|\+|,|/|;|<|=|>|\?|@|\[|\\|\]|\^|`|\{|\||\}|~|\s
	private static final String ILLEGAL_CHARACTER_REGEX = "!|\"|#|\\$|%|&|'|\\(|\\)|\\*|\\+|,|/|;|<|=|>|\\?|@|\\[|\\\\|\\]|\\^|`|\\{|\\||\\}|~|\\s";
	// ^(-|\.|\d).*
	private static final String ILLEGAL_START_REGEX = "^(-|\\.|\\d).*";
	
	private Document document;
	private Element rootElement;
	
	public XMLExportType() {
		rootElement = new Element("export");
		document = new Document(rootElement);
	}
	
	@Override
	public String getContentType() {
		return "application/xml";
	}

	@Override
	public String getFileExtension() {
		return "xml";
	}
	
	@Override
	public Document getContext() {
		return document;
	}

	@Override
	public void writeExport(ExternalContext externalContext) throws Exception {
		externalContext.setResponseCharacterEncoding("UTF-8");
		new XMLOutputter(Format.getPrettyFormat()).output(document, externalContext.getResponseOutputStream());
	}
	
	@Override
	public Element exportRow(IExportRow row) {
		Element currentElement = (Element) row.getParentRowId();
		if (currentElement == null) {
			currentElement = rootElement;
		}
		
		for (String namePart : row.getName()) {
			Element subElement = new Element(cleanElementName(namePart));
			currentElement.addContent(subElement);
			currentElement = subElement;
		}
		
		for (IExportCell cell : row.getCells()) {
			Element cellElement = currentElement;
			for (String namePart : cell.getName()) {
				Element subElement = cellElement.getChild(namePart);
				if (subElement == null) {
					subElement = new Element(cleanElementName(namePart));
					cellElement.addContent(subElement);
				}
				cellElement = subElement;
			}
			
			if (!cellElement.getText().equals("")) {
				String cellName = cellElement.getName();
				cellElement = cellElement.getParentElement();
				Element newCellElement = new Element(cellName);
				cellElement.addContent(newCellElement);
				cellElement = newCellElement;
			}
			cellElement.setText(cell.getValue());
		}
		
		return currentElement;
	}
	
	/**
	 * Cleans an element name so it doesn't contain any illegal characters.
	 * According to the Wikipedia article on XML:
	 * 
	 * Tag names cannot contain any of the characters !"#$%&'()*+,/;<=>?@[\]^`{|}~, nor a space character,
	 * and cannot start with -, ., or a numeric digit.
	 * @param name
	 * @return
	 */
	private static String cleanElementName(String name) {
		name = name.replaceAll(ILLEGAL_CHARACTER_REGEX, "_");
		if (name.matches(ILLEGAL_START_REGEX)) {
			name = "_" + name;
		}
		return name;
	}

}