SSEGeoService allows you to set the new Geolocation fields of any object by running an address string through the Google Geolocation API.

gistfile1.java

public class SSEGeoService 
{
    class GeoException extends Exception {}
    
    @future (callout=true)
    static public void setLocation(String sobj, String field, String id, String address)
    {
        if (String.isBlank(address)) {
            throw new SSEGeoService.GeoException('Address can not be blank.');
        }
        
        String latField;
        String longField;
        if (field.contains('__c')) {
            latField = field.replace('__c', '__Latitude__s');
            longField = field.replace('__c', '__Longitude__s');
        } else {
            latField = field + '__Latitude__s';
            longField = field + '__Longitude__s';
        }
        
        Map<String, Schema.SObjectType> gd = Schema.getGlobalDescribe();
        if (gd.get(sobj) == null) {
            throw new SSEGeoService.GeoException('SObject does not exist: `' + sobj + '`');
        }
        
        Map<String, Schema.SObjectField> fmap = gd.get(sobj).getDescribe().fields.getMap();
        if (fmap.get(latField) == null) {
            throw new SSEGeoService.GeoException('Field does not exist on SObject (`' + sobj + '`): `' + field + '`');
        }
        
        SObject obj = Database.query('Select Id, ' + latField + ', ' + longField + ' From ' + sobj + ' Where Id = \'' + id + '\'');
        if (obj == null) {
            throw new SSEGeoService.GeoException('Record does not exist on SObject (`' + sobj + '`): ID `' + id + '`');
        }
        
        address = EncodingUtil.urlEncode(address, 'UTF-8');
        
        Http h = new Http();
        HttpRequest req = new HttpRequest();
        req.setEndpoint('https://maps.googleapis.com/maps/api/geocode/json?address=' + address + '&sensor=false');
        req.setMethod('GET');
        req.setTimeout(60000);
        
        try {
            HttpResponse res = h.send(req);
            
            JSONParser parser = JSON.createParser(res.getBody());
            double lat = null;
            double lon = null;
            while (parser.nextToken() != null) {
                if ((parser.getCurrentToken() == JSONToken.FIELD_NAME) &&
                    (parser.getText() == 'location')) {
                       parser.nextToken();
                       while (parser.nextToken() != JSONToken.END_OBJECT) {
                           String txt = parser.getText();
                           parser.nextToken();
                           if (txt == 'lat') {
                               lat = parser.getDoubleValue();
                           } else if (txt == 'lng') {
                               lon = parser.getDoubleValue();
                           }
                       }
 
                }
            }
 
            if (lat != null && lon != null){
                obj.put(latField, lat);
                obj.put(longField, lon);
                update obj;
            }
        } catch (Exception e) {
            throw new SSEGeoService.GeoException(e.getMessage());
        }
    }
}