view flys-client/src/main/java/de/intevation/flys/client/server/FixingsKMChartServiceImpl.java @ 4421:0b0f415203f0

Add new Filter class to change caching Add new Filter class to avoid caching of GWT nocache files in browsers and http proxies. The new Filter class NoCacheFilter sets http headers to stop the proxies and browesers from storing the nocache files.
author Björn Ricks <bjoern.ricks@intevation.de>
date Tue, 06 Nov 2012 13:32:06 +0100
parents 51ed89b754ae
children
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package de.intevation.flys.client.server;

import de.intevation.artifacts.common.utils.XMLUtils;

import de.intevation.artifacts.httpclient.http.HttpClient;
import de.intevation.artifacts.httpclient.http.HttpClientImpl;

import de.intevation.artifacts.httpclient.exceptions.ConnectionException;

import de.intevation.artifacts.httpclient.http.response.StreamResponseHandler;

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

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.log4j.Logger;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;

public class FixingsKMChartServiceImpl
extends      HttpServlet
{
    private static final Logger log =
        Logger.getLogger(FixingsKMChartServiceImpl.class);

    public static final String SERVICE_NAME = "fixings-km-chart";

    public FixingsKMChartServiceImpl() {
    }

    public void doGet(HttpServletRequest req, HttpServletResponse resp) {

        log.info("FixingsKMChartServiceImpl.doGet");

        String url    = getServletContext().getInitParameter("server-url");
        String locale = req.getParameter("locale");
        String filter = req.getParameter("filter");

        if (filter == null || filter.length() == 0) {
            log.warn("Missing 'filter' parameter.");
            return;
        }

        if (locale == null || locale.length() == 0) {
            locale = "de";
        }

        Document filterDoc = XMLUtils.jsonToXML(filter);

        if (filterDoc == null) {
            log.warn("Creating filter document failed.");
            return;
        }

        InputStream in;

        try {
            HttpClient client = new HttpClientImpl(url, locale);
            in = (InputStream)client.callService(
                url, // XXX: Why? The URL is passed by construction already.
                SERVICE_NAME,
                filterDoc,
                new StreamResponseHandler());
        }
        catch (ConnectionException ce) {
            log.error(ce);
            return;
        }

        resp.setHeader("Content-Type", guessMIMEType(filterDoc));

        try {
            OutputStream out = resp.getOutputStream();

            byte [] buf = new byte[4096];
            int i = -1;
            while ((i = in.read(buf)) >= 0) {
                out.write(buf, 0, i);
            }
            out.flush();
        }
        catch (IOException ioe) {
            log.error(ioe);
        }
        finally {
            try { in.close(); }
            catch (IOException ioe) { /* ignored */ }
        }
    }

    protected static String guessMIMEType(Document document) {

        NodeList formats = document.getElementsByTagName("format");

        String format = "png";

        if (formats.getLength() > 0) {
            String type = ((Element)formats.item(0)).getAttribute("type");
            if (type.length() > 0) {
                format = type;
            }
        }

        return "image/" + format;
    }
}
// vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :

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