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

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Here is the source code for edu.cornell.mannlib.vitro.webapp.controller.json.JsonProducer.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 java.util.Arrays;
import java.util.List;

import javax.servlet.ServletException;

import org.apache.commons.lang.StringUtils;
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.beans.VClass;
import edu.cornell.mannlib.vitro.webapp.controller.VitroRequest;

/**
 * A base for the classes that produce JSON results. Contains some useful constants and convenience methods.
 */
public abstract class JsonProducer {
    private static final Log log = LogFactory.getLog(JsonProducer.class);

    /**
     * Process a list of Individuals into a JSON array that holds the Names and URIs.
     */
    protected JSONArray individualsToJson(List<Individual> individuals) throws ServletException {
        try {
            JSONArray ja = new JSONArray();
            for (Individual ent : individuals) {
                JSONObject entJ = new JSONObject();
                entJ.put("name", ent.getName());
                entJ.put("URI", ent.getURI());
                ja.put(entJ);
            }
            return ja;
        } catch (JSONException ex) {
            throw new ServletException("could not convert list of Individuals into JSON: " + ex);
        }
    }

    /**
     * Get the "vclassId" parameter from the request and instantiate the VClass.
     * 
     * There must be one, and it must be valid.
     */
    protected VClass getVclassParameter(VitroRequest vreq) {
        String vclassId = vreq.getParameter("vclassId");
        if (StringUtils.isEmpty(vclassId)) {
            log.error("parameter vclassId expected but not found");
            throw new IllegalStateException("parameter vclassId expected ");
        }
        return instantiateVclass(vclassId, vreq);
    }

    /**
     * Get one or more "vclassId" parameters from the request. Confirm that
     * there is at least one, and that all are valid.
     * 
     * Return value is never null and never empty.
     */
    protected List<String> getVclassIds(VitroRequest vreq) {
        String[] vclassIds = vreq.getParameterValues("vclassId");
        if ((vclassIds == null) || (vclassIds.length == 0)) {
            log.error("parameter vclassId expected but not found");
            throw new IllegalStateException("parameter vclassId expected ");
        }

        for (String vclassId : vclassIds) {
            instantiateVclass(vclassId, vreq);
        }

        return Arrays.asList(vclassIds);
    }

    private VClass instantiateVclass(String uri, VitroRequest vreq) {
        VClass vclass = vreq.getWebappDaoFactory().getVClassDao().getVClassByURI(uri);
        if (vclass == null) {
            log.error("Couldn't retrieve vclass '" + uri + "'");
            throw new IllegalStateException("Class " + uri + " not found");
        }
        return vclass;
    }

}