StaxParser.java

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package org.glassfish.flashlight.xml;

/**
 * An abstract class that you can build upon to make your own custom parser.
 * @author bnevins
 */

import java.io.*;
import java.util.*;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.xml.stream.*;
import static javax.xml.stream.XMLStreamConstants.END_DOCUMENT;
import static javax.xml.stream.XMLStreamConstants.END_ELEMENT;
import static javax.xml.stream.XMLStreamConstants.START_ELEMENT;

public abstract class StaxParser {

    abstract protected void read() throws XMLStreamException, EndDocumentException;

    public StaxParser(File f) throws XMLStreamException {
        try {
            xmlStream = new FileInputStream(f);
            createParser();
        }
        catch(IOException ioe) {
            throw new XMLStreamException(ioe);
        }
    }
    
    public StaxParser(String resource, ClassLoader cl) throws XMLStreamException {
        xmlStream = cl.getResourceAsStream(resource);
        createParser();
    }

    public StaxParser(InputStream is) throws XMLStreamException {
        xmlStream = is;
        createParser();
    }

    /**
     * The same as calling XmlStreamReader.next() except that we throw a special
     * Exception if the end of the document was reached
     * @return
     * @throws XMLStreamException
     * @throws xml.StaxParser.EndDocumentException if the end of the document is here
     */
     protected int next() throws XMLStreamException, EndDocumentException {
        int event = parser.next();
        if (event == END_DOCUMENT) {
            parser.close();
            throw new EndDocumentException();
        }
        return event;
    }

    /**
     * The cursor will be pointing at the START_ELEMENT of name when it returns.
     * note that skipTree must be called.  Otherwise we could be fooled by a
     * sub-element with the same name as an outer element
     *
     * @param name the Element to skip to
     * @throws javax.xml.stream.XMLStreamException
     */
    protected void skipTo(String name) throws XMLStreamException, EndDocumentException {
        while (true) {
            nextStart();
            // cursor is at a START_ELEMENT
            String localName = parser.getLocalName();
            if (name.equals(localName)) {
                return;
            } else {
                skipTree(localName);
            }
        }
    }

    /**
     * The cursor must be pointing at a START_ELEMENT.  Returns all attributes
     * in a Map
     * @return Map<String, String> of all attributes
     * @throws IllegalStateException if the cursor is not pointing at a START_ELEMENT
     */

    protected Map<String, String> parseAttributes() {
        int num = parser.getAttributeCount();
        Map<String, String> map = new HashMap<String, String>();

        for (int i = 0; i < num; i++) {
            map.put(parser.getAttributeName(i).getLocalPart(), parser.getAttributeValue(i));
        }

        return map;
    }
    /**
     * Skip to the first START_ELEMENT after the given START_ELEMENT name
     * This is useful for skipping past the root element
     * @param name The START_ELEMENT to skip past
     * @throws XMLStreamException if any errors
     * @throws xml.StaxParser.EndDocumentException if end of document reached first
     */
    protected void skipPast(String name) throws XMLStreamException, EndDocumentException {
        // Move to the first 'top-level' element under name
        // Return with cursor pointing to first sub-element
        skipTo(name);
        nextStart();
    }

    /**
     * Skip to the next START_ELEMENT
     * @throws XMLStreamException
     * @throws xml.StaxParser.EndDocumentException
     */
    protected void nextStart() throws XMLStreamException, EndDocumentException {
        while (next() != START_ELEMENT)
            ;
    }

    protected void close() {
        try {
            if (parser != null) {
                parser.close();
            }
        }
        catch (Exception e) {
            // ignore
        }
        try {
            if (xmlStream != null) {
                xmlStream.close();
            }
        }
        catch (Exception e) {
            // ignore
        }
    }

     /////////////////////  private below //////////////////////////////////////

     private void createParser() throws XMLStreamException {
        XMLInputFactory xif = XMLInputFactory.newInstance();
        parser = xif.createXMLStreamReader(xmlStream);
    }


     private void skipTree(String name) throws XMLStreamException, EndDocumentException {
        // The cursor is pointing at the start-element of name.
        // throw everything in this element away and return with the cursor
        // pointing at its end-element.
        while (true) {
            int event = next();
            if (event == END_ELEMENT && name.equals(parser.getLocalName())) {
                return;
            }
        }
    }

     // this is so we can return from arbitrarily nested calls -- it is VERY easy
     // to get into an infinite loop without this!
    protected static class EndDocumentException extends Exception {
        EndDocumentException() {
        }
    }
    private InputStream xmlStream;
    protected XMLStreamReader parser;
}