kmlmapproducerfactory.java

电子地图服务器,搭建自己的地图服务

/* Copyright (c) 2001 - 2007 TOPP - www.openplans.org.  All rights reserved.
 * This code is licensed under the GPL 2.0 license, availible at the root
 * application directory.
 */
package org.vfny.geoserver.wms.responses.map.kml;

import org.vfny.geoserver.global.WMS;
import org.vfny.geoserver.wms.GetMapProducer;
import org.vfny.geoserver.wms.GetMapProducerFactorySpi;
import java.util.Collections;
import java.util.Map;
import java.util.Set;


/**
 * KMLMapProducerFactory
 * This class is used as part of the SPI auto discovery process which enables
 * new format producers to be plugged in.
 *
 * @version $Id: KMLMapProducerFactory.java 7467 2007-08-28 22:29:03Z afabiani $
 */
public class KMLMapProducerFactory implements GetMapProducerFactorySpi {
    /**
     * this is just to check the requested mime type starts with this string,
     * since the most common error when performing the HTTP request is not to
     * escape the '+' sign in "kml+xml", which is decoded as a space
     * character at server side.
     */
    private static final String PRODUCE_TYPE = "kml";

    /** Official KML mime type
     * @TODO add KMZ support
     */
    public static final String MIME_TYPE = "application/vnd.google-earth.kml+xml";

    /** Set of supported mime types for the producers made by this Factory
     */
    private static final Set SUPPORTED_FORMATS = Collections.singleton(MIME_TYPE);

    /**
     * Creates a new KMLMapProducerFactory object.
     */
    public KMLMapProducerFactory() {
    }

    /**
     * Human readable description of output format.
     */
    public String getName() {
        return "Keyhole markup language producer";
    }

    /**
     * Discover what output formats are supported by the producers made by this factory.
     *
     * @return Set of supported mime types
     */
    public Set getSupportedFormats() {
        return SUPPORTED_FORMATS;
    }

    /**
     * Reports on the availability of this factory.  As no external libraries are
     * required for KML this should always be true.
     *
     * @return <code>true</code>
     */
    public boolean isAvailable() {
        return true;
    }

    /**
     * evaluates if this Map producer can generate the map format specified by
     * <code>mapFormat</code>
     *
     * <p>
     * In this case, true if <code>mapFormat</code> starts with "kml", as
     * both <code>"kml"</code> and <code>"kml+xml"</code> are
     * commonly passed.  Also true if <code>application/vnd.google-earth.kml</code>
     * is passed, since that is as close as we can get to the value advertised in the
     * capabilities document taking into account the common mistake of not escaping '+'.
     * We must do this as the most way to request an output format is to use the name
     * in the caps document.
     * </p>
     *
     * @TODO should this be image/kml and image/kml+xml?
     * @param mapFormat the mime type of the output map format requiered
     *
     * @return true if class can produce a map in the passed format.
     */
    public boolean canProduce(String mapFormat) {
        //MIME TYPE is spec compliant, as its what we advertise in the caps
        //document.  Keeping the startsWith kml, so shortcuts can be used. -ch
        return (mapFormat != null)
        && (mapFormat.startsWith(PRODUCE_TYPE)
        || mapFormat.startsWith("application/vnd.google-earth.kml"));
    }

    /**
     * Create an actual instance of a KMLMapProducer.
     *
     * @param mapFormat
     *            String which MUST match the supported formats. Call canProcess
     *            fisrt if you are unsure.
     *
     * @return GetMapProducer instance.
     *
     * @throws IllegalArgumentException
     *             DOCUMENT ME!
     */
    public GetMapProducer createMapProducer(String mapFormat, WMS wms)
        throws IllegalArgumentException {
        if (canProduce(mapFormat)) {
            return new KMLMapProducer(mapFormat, MIME_TYPE);
        }

        throw new IllegalArgumentException("Unable to produce format " + mapFormat);
    }

    /* (non-Javadoc)
     * @see org.geotools.factory.Factory#getImplementationHints()
     * This just returns java.util.Collections.EMPTY_MAP
     */
    public Map getImplementationHints() {
        return java.util.Collections.EMPTY_MAP;
    }
}