com.msbmsb.gogogeocode.GoGoGeocode.java Source code

Introduction

Here is the source code for com.msbmsb.gogogeocode.GoGoGeocode.java

Source

/******************************************************************************
* GoGoGeocode
* {@code GoGoGeocode} is intended to be a very simple java package for 
* geocoding an address to coordinates. The goal is to do minimal work to get 
* the minimal information.
    
* It uses the Google Geocoding API (V3). More information on this API is at: 
*   http://code.google.com/apis/maps/documentation/geocoding/. 
* There is no API key necessary for this version of the web service. 
* The API is subject to a query limit of 2,500 geolocation requests per day. 
* Any additional queries over this limit will yield a status code of 
* "OVER_QUERY_LIMIT"
    
* This class will return coordinates of -1,-1 for any unsuccessful geocoding 
* attempt. Coordinates are returned in string form as "longitude,latitude".
* 
* Author:       Mitchell Bowden <mitchellbowden AT gmail DOT com>
* License:      MIT License: http://creativecommons.org/licenses/MIT/
******************************************************************************/

package com.msbmsb.gogogeocode;

import com.msbmsb.gogogeocode.Coordinates;

import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.MultiThreadedHttpConnectionManager;
import org.apache.commons.httpclient.methods.GetMethod;
import org.apache.commons.httpclient.params.HttpClientParams;
import org.apache.commons.io.IOUtils;

import java.io.InputStreamReader;
import java.io.Reader;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;

/**
 * Main class for geocoding an address to long/lat coordinates
 */
public class GoGoGeocode {
    /**
     * URL for Google Geocoding API v3, xml output
     * No API key is needed for this version
     */
    private static final String GOOGLE_GEOCODE_URL_STUB = "http://maps.google.com/maps/api/geocode/xml?sensor=false&";

    private static final HttpClient httpClient = new HttpClient(new MultiThreadedHttpConnectionManager());

    /**
     * Empty default constructor for initialization
     */
    public GoGoGeocode() {
    }

    /**
     * Build the url given the string of a physical address
     * @param address the string representation of a physical address
     * @return full URL of API call, as String. null if address is empty
     */
    private static String buildURL(String address) throws UnsupportedEncodingException {
        if (address == null || address.equals("")) {
            return null;
        }

        String requestUrl = GOOGLE_GEOCODE_URL_STUB;
        requestUrl += "address=" + URLEncoder.encode(address, "UTF-8");

        return requestUrl;
    }

    /**
     * Given the string of an address, return a string representation of the
     * coordinates in the form of "longitude,latitude"
     * @param address the string representation of a physical address
     * @return String of coordinates in the form of "longitude,latitude"
     */
    public static String geocodeToString(String address) {
        return geocode(address).toString();
    }

    /**
     * Given the string of an address, return a Coordinates object that contains
     * the coordinate information extracted from the API response
     * @param address the string representation of a physical address
     * @return Coordinates object containing coordinate information from response
     */
    public static Coordinates geocode(String address) {
        Coordinates coords = new Coordinates();

        String requestUrl = "";
        try {
            requestUrl = buildURL(address);
        } catch (UnsupportedEncodingException uee) {
            uee.printStackTrace();
        }

        GetMethod getMethod = new GetMethod(requestUrl);
        getMethod.setFollowRedirects(true);

        try {
            httpClient.executeMethod(getMethod);

            // build the response object
            GoogleGeocodeResponse response = new GoogleGeocodeResponse(
                    IOUtils.toString(getMethod.getResponseBodyAsStream(), getMethod.getRequestCharSet()));
            /**
             * Parsing can be done via Dom Document as well: 
             * GoogleGeocodeResponse response = new GoogleGeocodeResponse(getMethod.getResponseBodyAsStream());
             */

            // only change coordinates from default if request successful
            if (response.successful()) {
                coords = response.getCoords();
            }
        } catch (Exception e) {
            System.out.println("Geocode exception: " + e.toString());
        } finally {
            getMethod.abort();
            getMethod.releaseConnection();
        }

        return coords;
    }
}