net.ontopia.infoset.content.ContentStoreServlet.java Source code

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Here is the source code for net.ontopia.infoset.content.ContentStoreServlet.java

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/*
 * #!
 * Ontopia Content Store
 * #-
 * Copyright (C) 2001 - 2013 The Ontopia Project
 * #-
 * 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,
 * WITHOUT 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 net.ontopia.infoset.content;

import java.io.IOException;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import net.ontopia.topicmaps.core.TopicMapIF;
import net.ontopia.topicmaps.nav2.core.NavigatorApplicationIF;
import net.ontopia.topicmaps.nav2.core.NavigatorRuntimeException;
import net.ontopia.topicmaps.nav2.utils.NavigatorUtils;
import org.apache.commons.io.IOUtils;

/**
 * INTERNAL: A servlet implementation that returns content stored in a
 * content store. It supports the following interface:</p>
 *
 * <pre>
 * Parameter   Explanation                                       Required
 * ---------   ------------------------------------------------  --------
 * uri         The URI of the content object, which must be of   Yes
 *             the form "x-ontopia:cms:XXX".
 * 
 * tmid        The identifier of the topic map from which the    Yes
 *             CO has been referenced.
 * 
 * ctype       The content-type to be given for the CO. Default  No
 *             is "application/octet-stream".
 * 
 * view        Whether to tell browser to open in browser        No
 *             window or to download into file. Values: 
 *             true/false. Default is to download to file 
 *             (false). 
 * 
 * filename    The filename to suggest. Default is to suggest    No
 *             none.
 * </pre>
 */
public class ContentStoreServlet extends HttpServlet {

    @Override
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException {
        // default values
        String ctype = "application/octet-stream";
        boolean view = false;

        // get values from request
        String uri = request.getParameter("uri");
        if (uri == null)
            throw new ServletException("Request parameter 'uri' required");

        String tmid = request.getParameter("tmid");
        if (tmid == null)
            throw new ServletException("Request parameter 'tmid' required");

        String filename = request.getParameter("filename");

        if (request.getParameter("ctype") != null)
            ctype = request.getParameter("ctype");

        if (request.getParameter("view") != null) {
            String value = request.getParameter("ctype").trim().toLowerCase();
            if ("true".equals(value))
                view = true;
            else if (!"false".equals(value))
                throw new ServletException("Request parameter 'view' must hold 'true' or 'false'");
        }

        // find the key
        if (!uri.startsWith("x-ontopia:cms:"))
            throw new ServletException("URI must begin with 'x-ontopia:cms:'");
        int key;
        try {
            key = Integer.parseInt(uri.substring(14));
        } catch (NumberFormatException e) {
            throw new ServletException("Content object ID was not an integer: '" + uri.substring(14) + "'");
        }

        // set response headers (content-disposition defined in RFC 2183)
        response.setContentType(ctype);
        String disposition = "attachment";
        if (view)
            disposition = "inline";
        if (filename != null)
            disposition = disposition + "; filename=" + filename;
        response.setHeader("Content-disposition", disposition);

        // get the content store
        NavigatorApplicationIF navApp = null;
        TopicMapIF tm = null;
        try {
            navApp = NavigatorUtils.getNavigatorApplication(getServletContext());
            tm = navApp.getTopicMapById(tmid);
            ContentStoreIF cs = getContentStore(tm, getServletContext());

            // get the content stream
            ContentInputStream istream;
            try {
                istream = cs.get(key);
            } catch (ContentStoreException e) {
                throw new ServletException(e);
            }

            // set the content length
            response.setContentLength(istream.getLength());

            // write content to output stream
            try {
                IOUtils.copy(istream, response.getOutputStream());
                istream.close();
            } catch (IOException e) {
                throw new ServletException(e);
            }
        } catch (NavigatorRuntimeException e) {
            throw new ServletException(e);
        } catch (ContentStoreException e) {
            throw new ServletException(e);
        } finally {
            if (navApp != null && tm != null)
                navApp.returnTopicMap(tm);
        }
    }

    // --- To be overridden, if necessary

    protected ContentStoreIF getContentStore(TopicMapIF tm, ServletContext ctxt) throws ContentStoreException {
        return ContentStoreUtils.getContentStore(tm, null);
    }

}