gistfile1.java

@Module(name="googlemaps", schemaVersion="1.0")
public class GoogleMapsModule
{
    private static final String PROTOTYPE_URL =
            "http://maps.googleapis.com/maps/api/distancematrix/xml?origins=%s&destinations=%s&units=%s&sensor=false";
    private static final String DISTANCE_XPATH = "//DistanceMatrixResponse/row/element/distance/text/text()";
    @Configurable
    @Optional
    @Default("MI")
    private DistanceUnit defaultDistanceUnit;

    @Processor
    public String getDistance(String origin, String destination, @Optional DistanceUnit distanceUnit) throws Exception {
        String effectiveUrl;
        if(distanceUnit != null) {
            effectiveUrl = String.format(PROTOTYPE_URL, origin, destination, distanceUnit);
        } else {
            effectiveUrl = String.format(PROTOTYPE_URL, origin, destination, defaultDistanceUnit);
        }
        InputStream responseStream = new URL(effectiveUrl).openConnection().getInputStream();
        try {
            return getXPath(responseStream, DISTANCE_XPATH);
        } finally {
            IOUtils.closeQuietly(responseStream);
        }
    }

    public void setDefaultDistanceUnit(DistanceUnit defaultDistanceUnit)
    {
        this.defaultDistanceUnit = defaultDistanceUnit;
    }

    private String getXPath(InputStream inputStream, String xpath) throws Exception {
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        dbf.setNamespaceAware(true);
        Document doc = dbf.newDocumentBuilder().parse(inputStream);
        XPathFactory factory = XPathFactory.newInstance();
        XPathExpression expr = factory.newXPath().compile(xpath);
        return (String) expr.evaluate(doc, XPathConstants.STRING);
    }
}