it.unibz.inf.xmlssd.metadator.xml.XMLProcessor.java Source code

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Here is the source code for it.unibz.inf.xmlssd.metadator.xml.XMLProcessor.java

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/*
 * Copyright 2009 Martin Palma
 * 
 * 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 it.unibz.inf.xmlssd.metadator.xml;

import gnu.xml.XMLPrinter;
import gnu.xquery.lang.XQuery;
import it.unibz.inf.xmlssd.metadator.helpers.Exporter;
import it.unibz.inf.xmlssd.metadator.helpers.UIHelper;
import it.unibz.inf.xmlssd.metadator.sqlite.SQLiteManager;

import java.io.File;
import java.io.IOException;
import java.io.StringWriter;
import java.io.Writer;
import java.util.Iterator;
import java.util.List;

import org.dom4j.Document;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.Node;

/**
 * Class for processing XML.
 * @author Martin Palma <martin@palma.bz>
 *
 */
public class XMLProcessor {

    private SQLiteManager backend;

    /**
     * Constructs the object.
     */
    public XMLProcessor() {
        backend = new SQLiteManager();
    }

    /**
     * Method which queries the data and returns the corresponding result. 
     * @param query
     * @return
     * @throws Throwable
     */
    public String get(String query) throws Throwable {
        // Creating a temporal snapshot of the stored data.
        File tmpFile = File.createTempFile("metadator", ".xml");

        // Modifing the query and adding the doc('file.xml')
        query = query.replaceAll("%%doc%%", "doc('" + tmpFile.getAbsolutePath() + "')");

        // Write XML for processing the XQuery/XPath
        Exporter exporter = new Exporter(tmpFile);
        exporter.export();

        StringWriter aStringWriter = new StringWriter();
        XMLPrinter aXMLWriter = new XMLPrinter(aStringWriter);

        XQuery aXQuery = new XQuery();
        aXQuery.eval(query, (Writer) aXMLWriter);

        aXMLWriter.flush();
        aStringWriter.flush();

        String result = aStringWriter.getBuffer().toString();

        // Remove tmp file
        tmpFile.delete();

        return (result.equals("")) ? "No result!" : result;
    }

    /**
     * Method which returns only a simple list of photos for displaying it in the
     * deletion dialog.
     * @return
     * @throws IOException 
     */
    public String getListOfPhotos() throws IOException {
        Document document = DocumentHelper.createDocument();
        Element root = document.addElement("metadator");

        List list = backend.get().selectNodes("//metadator/photo");
        for (Iterator i = list.iterator(); i.hasNext();) {
            Element element = (Element) i.next();

            Node author = element.selectSingleNode("//author");
            Node title = element.selectSingleNode("//title");

            root.addElement("photo").addAttribute("id", element.attributeValue("id"))
                    .addAttribute("author", author.getStringValue())
                    .addAttribute("filename", element.attributeValue("filename"))
                    .addAttribute("title", title.getStringValue());
        }

        return UIHelper.prettyPrintString(document.asXML());
    }

}