CODEWITHSUNDEEP
rdfjena
user2057437
user2057437

Reputation: 81

To display RDF using jena API's in java

I have created a few methods in StoryModel. If there is any mistake in the code I really appreciate corrections.

public class StoryModel {

    String dbName = "DB3";
    String sns =  "http://somebook/SemBook#";
    String ns;
    Dataset ds;
    OntModel om;

    // create model and connect to database
    public StoryModel(String storyName){

        ns = sns + storyName;
        ds = TDBFactory.createDataset(dbName);
        om = ModelFactory.createOntologyModel();

    }

    // create classes in model
    public void initModel() {

        om.createClass(ns + "Person");
        om.createClass(ns + "Event");
        om.createClass(ns + "Place");
        om.createClass(ns + "Time");
        om.createClass(ns + "Object");
        saveModel();
    }   

    //Read & write in database
    //Display it
    public void saveModel() {

        ds.begin(ReadWrite.WRITE);
        om.write(System.out, "RDF/XML-ABBREV");

    }

    // Create resource to class in model
    public Resource createResource(String resourceName, String clsName) {

        OntResource resource = om.createOntResource(ns + resourceName);
        String ruri = ns + resource;
        OntClass clsuri = om.getOntClass(ns + clsName);

        Individual i = om.createIndividual(ruri, clsuri);

        return i;

    }

    /*
     * Return an RDF resource object given the URI of the resource as a string. The
     * URI can be represented in full, or as a "prefix:localName".
     * @param resourceName The full URI of the resource
     * @return An RDF resource object
     */

    public Resource stringToResource( String resourceName ) {

        String resourceURI = om.expandPrefix( resourceName );

        return om.getResource( resourceURI );

    }

    // Delete the resource
    public void deleteResource(String resourceName) {

        try {
            OntResource resource = om.getOntResource(ns + resourceName);

            if (resource != null) 
            {
               resource.remove();
            }
            else {
                System.out.println("Resource not present");
            }   
        }
        catch (Exception e) { }         
    }
}

In SemBookMain I created a model and initialized classes to resource using methods which are created in StoryModel and display it 

public class SemBookMain {

    public static void main(String[] args) {

        // create and initialize a model
        StoryModel sm = new StoryModel("alice");
        //sm.saveModel();
        sm.initModel();

        // add resources
        String clsName = "Person";
        String[] ar = {"Alice", "Peter", "Ben", "Robin"};

        for (String r : ar) {

            Resource res = sm.createResource(r, clsName);

        }
        sm.saveModel();

    }

}

I am really sorry I added output as comment below so please see to my comment.

I don't understand about ERROR 1 & 2 and why the resource are not displayed. There is something I am missing but couldn't figure it out.

Upvotes: 0

Views: 687

Answers (1)

AndyS
AndyS

Reputation: 16630

ds.begin(ReadWrite.WRITE); but no ds.commit

initModel calls saveModel and then you later call saveModel again.

Follow the code patterns at:

http://jena.apache.org/documentation/tdb/tdb_transactions.html#write-transactions

Upvotes: 2

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