JSONFormat.java

/* Copyright (c) 2001 - 2007 TOPP - www.openplans.org.  All rights reserved.
 * This code is licensed under the GPL 2.0 license, availible at the root
 * application directory.
 */
package org.geoserver.rest;

import java.io.BufferedWriter;
import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

import net.sf.json.JSON;
import net.sf.json.JSONArray;
import net.sf.json.JSONNull;
import net.sf.json.JSONObject;

import org.restlet.data.MediaType;
import org.restlet.resource.OutputRepresentation;
import org.restlet.resource.Representation;

/**
 * The JSONFormat class uses json-lib to convert a map directly to the json equivalent and back.
 *
 * @author David Winslow <dwinslow@openplans.org>
 */
public class JSONFormat implements DataFormat {

    private MediaType myType;

    public JSONFormat(){
        this(new MediaType("text/json"));
    }

    public JSONFormat(MediaType type){
        myType = type;
    }

    public Representation makeRepresentation(final Object o) {
        return new OutputRepresentation(myType) {
                public void write(OutputStream os) {
                    try {
                        Writer outWriter = new BufferedWriter(new OutputStreamWriter(os));

                        outWriter.flush();

                        JSON obj = (JSON)toJSONObject(o);

                        obj.write(outWriter);
                        outWriter.flush();
                    } catch (Exception e) {
                        try {
                            // how to handle?
                            os.write(("Couldn't write json because of " + e.toString()).getBytes());
                            e.printStackTrace();
                        } catch (IOException ioe) {
                        }
                    }
                }

                public Object toJSONObject(Object obj) {
                    if (obj instanceof Map) {
                        Map m = (Map) obj;
                        JSONObject json = new JSONObject();
                        Iterator it = m.entrySet().iterator();

                        while (it.hasNext()) {
                            Map.Entry entry = (Map.Entry) it.next();
                            json.put((String) entry.getKey(), toJSONObject(entry.getValue()));
                        }

                        return json;
                    } else if (obj instanceof Collection) {
                        Collection col = (Collection) obj;
                        JSONArray json = new JSONArray();
                        Iterator it = col.iterator();

                        while (it.hasNext()) {
                            json.add(toJSONObject(it.next()));
                        }

                        return json;
                    } else if (obj instanceof Number) {
                        return obj;
                    } else if (obj == null) {
                        return JSONNull.getInstance();
                    } else {
                        return obj.toString();
                    }
                }
            };
    }

    public Object readRepresentation(Representation rep) {
        try {
            JSONObject obj = JSONObject.fromObject(rep.getText());

            return obj;

            /*
               Object maybeMap = toMap(obj);
               if (maybeMap instanceof Map){
               return (Map) maybeMap;
               }

            // TODO: figure out what to do rather than this kind of arbitrary thing
            Map map = new HashMap();
            map.put("context", maybeMap);

            return map; */
        } catch (IOException ioe) {
            return new HashMap();
        }
    }

    /*
       protected Object toMap(Object json){
       if (json instanceof JSONObject){
       Map m = new HashMap();
       Iterator it = ((JSONObject)json).keys();
       while (it.hasNext()){
       String key = (String)it.next();
       m.put(key, toMap(((JSONObject)json).get(key)));
       }
       return m;
       } else if (json instanceof JSONArray){
       List l = new ArrayList();
       for (int i = 0; i < ((JSONArray)json).length(); i++){
       l.add(toMap(((JSONArray)json).get(i)));
       }
       return l;
       } else if (json instanceof JSONNull){
       return null;
       } else {
       return json;
       }
       } */
}