de.decoit.visa.http.ajax.handlers.ExportRDFHandler.java Source code

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Here is the source code for de.decoit.visa.http.ajax.handlers.ExportRDFHandler.java

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/*
 *  Copyright (C) 2013, DECOIT GmbH
 *
 *   This file is part of VISA Topology-Editor.
 *
 *   VISA Topology-Editor is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by the
 *   Free Software Foundation, either version 3 of the License, or (at your option)
 *   any later version.
 *
 *   VISA Topology-Editor is distributed in the hope that it will be useful, but
 *   WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 *   or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 *   more details.
 *
 *   You should have received a copy of the GNU General Public License along with
 *   VISA Topology-Editor. If not, see <http://www.gnu.org/licenses/>.
 */

package de.decoit.visa.http.ajax.handlers;

import java.io.IOException;
import java.nio.file.Path;
import org.apache.log4j.Logger;
import org.json.JSONException;
import org.json.JSONObject;
import com.sun.net.httpserver.HttpExchange;
import de.decoit.visa.TEBackend;
import de.decoit.visa.http.QueryString;
import de.decoit.visa.http.ajax.AJAXServer;

/**
 * This handler tells the {@link de.decoit.visa.rdf.RDFManager RDFManager} to serialize the current RDF model
 * as RDF/XML and write it to a file. The file is located in the 'export'
 * directory of the frontend's webserver and can be accessed by the frontend.<br>
 * <br>
 * On success, a JSON object will be returned containing the path of the created
 * file (key: file).<br>
 * <br>
 * Any exception thrown during the processing of the request will cause the
 * request to fail.
 * <br>
 * Possible return messages of this handler are:<br>
 * - ajaxSuccess (success)<br>
 * - ajaxException (exception caught and no recovery attempt made)<br>
 * - ajaxMissing (missing arguments)
 *
 * @author Thomas Rix
 * @see AJAXServer
 * @see DefaultHandler
 */
public class ExportRDFHandler extends DefaultHandler {
    private static Logger log = Logger.getLogger(ExportRDFHandler.class.getName());

    @Override
    public void handle(HttpExchange he) throws IOException {
        log.info(he.getRequestURI().toString());

        // Get the URI of the request and extract the query string from it
        QueryString queryParameters = new QueryString(he.getRequestURI());

        // Create StringBuilder for the response
        String response = null;

        // Check if the query parameters are valid for this handler
        if (this.checkQueryParameters(queryParameters)) {
            try {
                Path outFile = TEBackend.getExportPath().resolve(queryParameters.get("file").get());

                TEBackend.RDF_MANAGER.writeRDF(outFile);

                JSONObject rv = new JSONObject();
                rv.put("status", AJAXServer.AJAX_SUCCESS);
                rv.put("file", outFile.toString());
                response = rv.toString();
            } catch (Throwable ex) {
                TEBackend.logException(ex, log);

                // Exception was thrown during cable removal
                JSONObject rv = new JSONObject();
                try {
                    rv.put("status", AJAXServer.AJAX_ERROR_EXCEPTION);
                    rv.put("type", ex.getClass().getSimpleName());
                    rv.put("message", ex.getMessage());
                    rv.put("topology", TEBackend.TOPOLOGY_STORAGE.genTopologyJSON());
                } catch (JSONException e) {
                    /* Ignore */
                }

                response = rv.toString();
            }
        } else {
            // Missing or malformed query string, set response to error code
            JSONObject rv = new JSONObject();
            try {
                rv.put("status", AJAXServer.AJAX_ERROR_MISSING_ARGS);
            } catch (JSONException exc) {
                /* Ignore */
            }

            response = rv.toString();
        }

        // Send the response
        sendResponse(he, response);
    }

    /**
     * Check if the provided QueryString object contains all keys required by
     * this handler and if their values are valid.
     *
     * @param pQueryString A QueryString object with all query parameters of the
     *            request
     * @return true if no problems were found, false if something is missing or
     *         malformed
     */
    private boolean checkQueryParameters(QueryString pQueryString) {
        boolean rv = true;

        // The file key must be present
        if (rv && (!pQueryString.containsKey("file") || pQueryString.get("file").get().isEmpty())) {
            rv = false;
        }

        return rv;
    }
}