org.znerd.yaff.activation.XMLDataSource.java Source code

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Here is the source code for org.znerd.yaff.activation.XMLDataSource.java

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// See the COPYRIGHT file for copyright and license information
package org.znerd.yaff.activation;

import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.InputStream;
import java.io.IOException;
import java.io.OutputStream;

import javax.activation.DataSource;

import org.apache.commons.io.IOUtils;

import org.xins.common.MandatoryArgumentChecker;
import org.xins.common.text.TextUtils;
import org.xins.common.text.ParseException;
import org.xins.common.xml.Element;
import org.xins.common.xml.ElementParser;

/**
 * Implementation of a <code>DataSource</code> for parsed XML content.
 *
 * @author <a href="mailto:ernst@ernstdehaan.com">Ernst de Haan</a>
 */
public final class XMLDataSource extends Object implements XDataSource {

    //-------------------------------------------------------------------------
    // Constructors
    //-------------------------------------------------------------------------

    /**
     * Constructs a new <code>XMLDataSource</code> from an existing
     * <code>DataSource</code> object.
     *
     * @param dataSource
     *    the {@link DataSource}, cannot be <code>null</code>.
     *
     * @throws IllegalArgumentException
     *    if <code>dataSource == null</code>.
     *
     * @throws IOException
     *    if there was an I/O error while reading from the input stream of the
     *    data source.
     *
     * @throws ParseException
     *    if there was a parsing error while parsing the content as XML.
     */
    public XMLDataSource(DataSource dataSource) throws IllegalArgumentException, IOException, ParseException {

        // Check preconditions
        MandatoryArgumentChecker.check("dataSource", dataSource);

        // The DataSource could be an XDataSource instance
        XDataSource xds = (dataSource instanceof XDataSource) ? (XDataSource) dataSource : null;

        // Populate fields
        _file = (xds != null) ? xds.getFile() : null;
        _name = dataSource.getName();
        _lastModified = (xds != null) ? xds.lastModified() : System.currentTimeMillis();
        _xml = new ElementParser().parse(dataSource.getInputStream());
    }

    /**
     * Constructs a new <code>XMLDataSource</code> using the specified
     * parameters.
     *
     * <p>If <code>name == null &amp;&amp; file != null</code>, then
     * <code>file.{@linkplain File#getName() getName()}</code> is used as the
     * name.
     *
     * @param xml
     *    the XML {@link Element}, cannot be <code>null</code>.
     *
     * @param file
     *    the associated {@link File}, or <code>null</code> if none.
     *
     * @param name
     *    the file name, or <code>null</code>.
     *
     * @param lastModified
     *    the last modified time stamp, must be &gt;= <code>0L</code>.
     *
     * @throws IllegalArgumentException
     *    if <code>xml == null || lastModified &lt;= 0L</code>.
     */
    public XMLDataSource(Element xml, File file, String name, long lastModified) throws IllegalArgumentException {

        // Check preconditions
        MandatoryArgumentChecker.check("xml", xml);
        if (lastModified <= 0L) {
            throw new IllegalArgumentException("lastModified (" + lastModified + "L) <= 0L");
        }

        // Populate fields
        _file = file;
        _name = (name == null && file != null) ? file.getName() : name;
        _lastModified = lastModified;
        _xml = (Element) xml.clone();
    }

    /**
     * Constructs a new <code>XMLDataSource</code> using only an XML
     * <code>Element</code>.
     *
     * @param xml
     *    the XML {@link Element}, cannot be <code>null</code>.
     *
     * @throws IllegalArgumentException
     *    if <code>xml == null</code>.
     */
    public XMLDataSource(Element xml) throws IllegalArgumentException {

        // Check preconditions
        MandatoryArgumentChecker.check("xml", xml);

        // Populate fields
        _file = null;
        _name = null;
        _lastModified = System.currentTimeMillis();
        _xml = (Element) xml.clone();
    }

    //-------------------------------------------------------------------------
    // Fields
    //-------------------------------------------------------------------------

    /**
     * The size of the data. Initially <code>-1</code>, meaning undetermined.
     */
    private int _size = -1;

    /**
     * The name. Can be <code>null</code>.
     */
    private final String _name;

    /**
     * The last modified time stamp.
     */
    private final long _lastModified;

    /**
     * The encapsulated abstract pathname. Can be <code>null</code>.
     */
    private final File _file;

    /**
     * The XML <code>Element</code>. Can be <code>null</code>.
     */
    private final Element _xml;

    //-------------------------------------------------------------------------
    // Methods
    //-------------------------------------------------------------------------

    private byte[] getBytes() {
        return TextUtils.toUTF8(_xml.toString());
    }

    public InputStream getInputStream() throws IOException {
        byte[] bytes = getBytes();
        if (_size < 0) {
            _size = bytes.length;
        }
        return new ByteArrayInputStream(bytes);
    }

    public OutputStream getOutputStream() throws IOException {
        throw new IOException("Operation not supported.");
    }

    public String getContentType() {
        return "text/xml";
    }

    public String getName() {
        return _name;
    }

    public long lastModified() throws DataAccessException {
        return _lastModified;
    }

    public int length() throws DataAccessException {
        if (_size < 0) {
            _size = getBytes().length;
        }
        return _size;
    }

    public File getFile() {
        return _file;
    }

    // TODO: Document
    public Element getXML() {
        return (Element) _xml.clone();
    }
}