org.eclipse.virgo.build.p2tools/src/main/java/org/eclipse/virgo/build/p2tools/instructions/FeatureParser.java

package org.eclipse.virgo.build.p2tools.instructions;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;

import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;

import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

/**
 * 
 * Parses a feature in search for the specific 'autostart' attribute of the element plugin. The attribute is case sensitive so if's written incorrectly it'll be ignored.
 * <p />
 *
 * <strong>Concurrent Semantics</strong><br />
 * Not thread-safe.
 */
public class FeatureParser extends DefaultHandler {

    private ArrayList<String> result;

    private final SAXParserFactory parserFactory = SAXParserFactory.newInstance();

    private SAXParser parser;

    public FeatureParser() {
        try {
            this.parser = this.parserFactory.newSAXParser();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    @Override
    public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
        if ("plugin".equals(qName)) {
            processAutostart(attributes);
        }
    }

    public ArrayList<String> parse(File featureXml) throws IOException {
        this.result = new ArrayList<String>();
        if (featureXml.exists()) {
            InputStream input = null;
            try {
                input = new BufferedInputStream(new FileInputStream(featureXml));
                this.parser.parse(input, this);
            } catch (Exception e) {
            } finally {
                input.close();
            }
            return this.result;
        }
        return null;
    }

    private void processAutostart(Attributes attributes) {
        if (attributes.getValue("autostart").equals("true")) {
            this.result.add(attributes.getValue("id"));
        }
    }

}