edu.cornell.mannlib.vitro.webapp.controller.json.GetEntitiesByVClassContinuation.java Source code

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Here is the source code for edu.cornell.mannlib.vitro.webapp.controller.json.GetEntitiesByVClassContinuation.java

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/* $This file is distributed under the terms of the license in /doc/license.txt$ */

package edu.cornell.mannlib.vitro.webapp.controller.json;

import static edu.cornell.mannlib.vitro.webapp.controller.json.JsonServlet.REPLY_SIZE;

import java.util.ArrayList;
import java.util.List;
import java.util.ListIterator;

import javax.servlet.ServletException;
import javax.servlet.http.HttpSession;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import edu.cornell.mannlib.vitro.webapp.beans.Individual;
import edu.cornell.mannlib.vitro.webapp.controller.VitroRequest;

/**
 * 
 */
public class GetEntitiesByVClassContinuation extends JsonArrayProducer {
    private static final Log log = LogFactory.getLog(GetEntitiesByVClassContinuation.class);

    protected GetEntitiesByVClassContinuation(VitroRequest vreq) {
        super(vreq);
    }

    @Override
    protected JSONArray process() throws ServletException {
        log.debug("in getEntitiesByVClassContinuation()");
        String resKey = vreq.getParameter("resultKey");
        if (resKey == null)
            throw new ServletException("Could not get resultKey");
        HttpSession session = vreq.getSession();
        if (session == null)
            throw new ServletException("there is no session to get the pervious results from");
        @SuppressWarnings("unchecked")
        List<Individual> entsInVClass = (List<Individual>) session.getAttribute(resKey);
        if (entsInVClass == null)
            throw new ServletException("Could not find List<Individual> for resultKey " + resKey);

        List<Individual> entsToReturn = new ArrayList<Individual>(REPLY_SIZE);
        boolean more = false;
        int count = 0;
        /* we have a large number of items to send back so we need to stash the list in the session scope */
        if (entsInVClass.size() > REPLY_SIZE) {
            more = true;
            ListIterator<Individual> entsFromVclass = entsInVClass.listIterator();
            while (entsFromVclass.hasNext() && count <= REPLY_SIZE) {
                entsToReturn.add(entsFromVclass.next());
                entsFromVclass.remove();
                count++;
            }
            if (log.isDebugEnabled())
                log.debug("getEntitiesByVClassContinuation(): Creating reply with continue token,"
                        + " sending in this reply: " + count + ", remaing to send: " + entsInVClass.size());
        } else {
            //send out reply with no continuation
            entsToReturn = entsInVClass;
            count = entsToReturn.size();
            session.removeAttribute(resKey);
            if (log.isDebugEnabled())
                log.debug("getEntitiesByVClassContinuation(): sending " + count + " Ind without continue token");
        }

        //put all the entities on the JSON array
        JSONArray ja = individualsToJson(entsToReturn);

        //put the responseGroup number on the end of the JSON array
        if (more) {
            try {
                JSONObject obj = new JSONObject();
                obj.put("resultGroup", "true");
                obj.put("size", count);

                StringBuffer nextUrlStr = vreq.getRequestURL();
                nextUrlStr.append("?").append("getEntitiesByVClass").append("=1&").append("resultKey=")
                        .append(resKey);
                obj.put("nextUrl", nextUrlStr.toString());

                ja.put(obj);
            } catch (JSONException je) {
                throw new ServletException(je.getMessage());
            }
        }
        log.debug("done with getEntitiesByVClassContinuation()");
        return ja;
    }

}