edu.illinois.whereru.JSONObjectParser.java Source code

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Here is the source code for edu.illinois.whereru.JSONObjectParser.java

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/*
* 
* Copyright (C) 2012 Hyuk Don Kwon
*
* 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 edu.illinois.whereru;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import com.google.android.maps.OverlayItem;

/*
 * TODO: find why location stored in DB is null
 * do buildFriendOverlays, 
 * for each different friend, add a dummy node containing user id and name.
 */
public class JSONObjectParser {

    /* JSON object tags */
    public static final String TAG_SUCCESS = "success";
    public static final String TAG_MESSAGE = "message";
    public static final String TAG_INSERT_ID = "insert_id";
    public static final String TAG_FRIENDS_INFO = "friends_info";
    public static final String TAG_FRIEND_NAME = "nickname";
    public static final String TAG_FRIEND_ID = "id";
    public static final String TAG_LATITUDE = "latitude";
    public static final String TAG_LONGITUDE = "longitude";
    public static final String TAG_TIME_STAMP = "time_stamp";

    /**
     * Returns the list of marker overlay items representing locations of frends.
     * The json object must contain friend informations, such as id, location, and time stamp.
     * 
     * Exits when json is not in the expected format. 
     * 
     * @param json a result returned from DB server 
     * @return     the list of marker overlay items parsed from json 
     * @throws JSONException 
     */
    public static List<OverlayItem> parseOverlayItems(JSONObject json) throws JSONException {

        ArrayList<OverlayItem> items = new ArrayList<OverlayItem>();

        JSONArray friendsInfo = json.getJSONArray(TAG_FRIENDS_INFO);

        for (int i = 0; i < friendsInfo.length(); i++) {
            if (!friendsInfo.isNull(i)) {
                JSONObject obj = friendsInfo.getJSONObject(i);
                String userId = obj.getString(TAG_FRIEND_ID);
                double latitude = obj.getDouble(TAG_LATITUDE);
                double longitude = obj.getDouble(TAG_LONGITUDE);
                String timeStamp = obj.getString(TAG_TIME_STAMP);
                OverlayItem item = MarkerOverlayItem.newOverlayItem(latitude, longitude, userId, timeStamp);
                items.add(item);
            }
        }

        return items;
    }

    /**
     * Extracts profile from DB's response.
     * One profile per friend.
     * 
     * @param json a result returned from DB
     * @return list of profiles
     * @throws JSONException 
     */
    public static ArrayList<Profile> parseDistinctProfile(JSONObject json) throws JSONException {

        HashSet<Profile> set = new HashSet<Profile>();

        JSONArray friendsInfo = json.getJSONArray(TAG_FRIENDS_INFO);

        for (int i = 0; i < friendsInfo.length(); i++) {
            if (!friendsInfo.isNull(i)) {
                JSONObject obj = friendsInfo.getJSONObject(i);
                String id = obj.getString(TAG_FRIEND_ID);
                String nickname = obj.getString(TAG_FRIEND_NAME);
                set.add(new Profile(id, nickname));
            }
        }

        return new ArrayList<Profile>(set);
    }

    /**
     * Returns a boolean indicating a successful DB queries set by DB server.
     * True if DB query was successful, false otherwise.
     * 
     * Exits if json is not the expected format.
     * 
     * @param json a result returned from DB server
     * @return     boolean indicating successful DB queries
     */
    public static boolean getSuccess(JSONObject json) {
        boolean success = false;

        try {
            success = json.getInt(TAG_SUCCESS) == 1;
        } catch (JSONException e) {
            e.printStackTrace();
        }

        return success;
    }

    /**
     * Returns unique user id set by DB server.
     * It is the insert id to global user info table in DB
     * 
     * Exits exception if
     *  
     * @param json a result returned from DB
     * @return      unique user id
     */
    public static int getUserId(JSONObject json) {
        int userId = -1;

        try {
            userId = json.getInt(TAG_INSERT_ID);
        } catch (JSONException e) {
            e.printStackTrace();
        }

        return userId;
    }
}