sapience.features.streams.kml.KMLRetriever.java Source code

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Here is the source code for sapience.features.streams.kml.KMLRetriever.java

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/**
 * Copyright 2010 Institute for Geoinformatics (ifgi)
 *
 * 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,
 * ITHOUT 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 sapience.features.streams.kml;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URL;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;

import org.apache.commons.io.IOUtils;

public class KMLRetriever {

    /**
     * Tries to fetch a KML file from the given URL. If it points to a zipped KML, it will
     * be extracted. Makes use of caching.
     * 
     * @param url
     * @return
     * @throws IOException
     */
    public File fetch(URL url) throws IOException {
        StringBuffer pre = new StringBuffer(System.getProperty("java.io.tmpdir"));
        if (!(pre.toString().endsWith("/") || pre.toString().endsWith("\\")))
            pre.append(System.getProperty("file.separator"));
        pre.append("cached");
        pre.append(url.hashCode());

        File kml = new File(pre.toString() + ".kml");

        if (kml.createNewFile()) {
            InputStream in = null;
            OutputStream out = null;
            try {
                in = fetchStream(url);
                out = new FileOutputStream(kml);
                IOUtils.copy(in, out);
            } catch (IOException e) {
                throw e;
            } finally {
                IOUtils.closeQuietly(in);
                IOUtils.closeQuietly(out);
            }
        }
        return kml;
    }

    /**
     * Directly returns the input stream coming from the URL (or the zipped
     * KML). Does not cache. 
     * 
     * @param url
     * @return
     * @throws IOException
     */
    public InputStream fetchStream(URL url) throws IOException {
        InputStream in = null;

        if (getSuffix(url) == ".kmz")
            in = extractSource(url, "doc.kml");
        else
            in = url.openConnection().getInputStream();

        return in;
    }

    /**
     * If the resource is hidden in a ZIP file, download, cache, and extract resource
     * 
     * @param url
     * @return the input stream with the given source
     * @throws IOException 
     */
    private InputStream extractSource(URL url, String entry) throws IOException {
        InputStream in = null;
        OutputStream out = null;
        try {

            File f = File.createTempFile("zippedSource", ".zip");
            out = new FileOutputStream(f);
            in = url.openStream();

            IOUtils.copy(in, out);
            ZipFile zip = new ZipFile(f);
            ZipEntry ze = zip.getEntry(entry);
            return zip.getInputStream(ze);

        } catch (IOException e) {
            throw e;
        } finally {
            IOUtils.closeQuietly(in);
            IOUtils.closeQuietly(out);
        }

    }

    /**
     * Checks if .KML or .KMZ appears somewhere in path 
     * 
     * @param url
     * @throws ParserException 
     * @throws MareDefinedException
     */
    private String getSuffix(URL url) throws IOException {
        if (url.getFile().endsWith(".kml"))
            return ".kml";
        else if (url.getFile().endsWith(".kmz"))
            return ".kmz";
        else
            throw new IOException("validation.file.unsupported");
    }

}