Extract a Open Graph value from a web page

["Meraj A. Khan" <me...@gmail.com>]

Hi All,

I am trying to retrieve an object value as in subject-predicate-object
from a web page and using the following code , the page I am
extracting it from is
http://www.macmall.com/p/Apple-Mac-Mini/product~dpno~13312163~pdp.ijcehjd

as you can clearly see it has og markup using RDFa , however the below
code fails  to extract any og values  , can you please let me know
what I might be doing wrong, the property Name that I am trying to
extract is OGP.imageUrl

Thanks.

private static String retrieveOGPProperty(String URL,String propertyName) {

logger.trace("Entering the method retrieveOGPProperty ");
String propertyValue = null;
OGP ogp = OGP.getInstance();
        org.openrdf.sail.Sail store = new org.openrdf.sail.memory.MemoryStore();
        try {
store.initialize();
} catch (SailException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
        try {
org.openrdf.repository.RepositoryConnection conn = new
org.openrdf.repository.sail.SailRepository(store).getConnection();
RepositoryResult<org.openrdf.model.Statement> statements =
conn.getStatements(RDFUtils.uri(URL), ogp.imageURL, null,false);
if(statements.hasNext()){
//get the first property
Value object = statements.next().getObject();
propertyValue = object.stringValue();
}
} catch (RepositoryException e) {
// Log the error and ignore it
logger.error("Error occured while extracting the OGP property "+propertyName,e);
}

        logger.trace("Exiting the method retrieveOGPProperty ");

        return propertyValue;
}