Jena Sparql Error java.lang.Integer

问题:

I have the following code:

    RestClient client = new RestClient("http://localhost:8080/scheduler.core/rest/services/discoverSensors");

    client.AddParam("userID", "[e-mail]");
    client.AddParam("longitude", "4.3512725830078125");
    client.AddParam("latitude", "50.84761359783461");
    client.AddParam("radius", "15.0");
    client.AddHeader("accept", "application/xml");

    try {
        client.Execute(RestClient.RequestMethod.GET);
    } catch (Exception e) {
        e.printStackTrace();
    }

    String response = client.getResponse();
    //System.out.println(response);

    DocumentBuilder db = null;
    try {
        db = DocumentBuilderFactory.newInstance().newDocumentBuilder();
    } catch (ParserConfigurationException e) {
        // TODO Auto-generated catch block

        System.out.println("error");
    }

    InputSource is = new InputSource();
    is.setCharacterStream(new StringReader(response));

    Document doc = db.parse(is);
    NodeList nodes = doc.getElementsByTagName("SensorType");

    // Getting the id of the sensor
    for(int x=0,size= nodes.getLength(); x<size; x++) {

        String resourceID = nodes.item(x).getAttributes().getNamedItem("id").getNodeValue();

        String sparqlQueryString = "select ?sensor ?lat ?lng "+
                                   "from <http://lsm.deri.ie/OpenIoT/demo/sensormeta#> " +
                                   "where{?sensor <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://purl.oclc.org/NET/ssnx/ssn#Sensor>."+
                                   "?sensor <http://lsm.deri.ie/ont/lsm.owl#hasSensorType> <http://lsm.deri.ie/resource/8a8291b73215690e013215a4c0d00f17>."+
                                   "?sensor <http://www.loa-cnr.it/ontologies/DUL.owl#hasLocation> ?location."+
                                   "?location <http://www.w3.org/2003/01/geo/wgs84_pos#lat> ?lat."+
                                   "?location <http://www.w3.org/2003/01/geo/wgs84_pos#long> ?lng."+
                                   "}limit 100";

        System.out.println(resourceID);
        System.out.println(sparqlQueryString);

        Query query = QueryFactory.create(sparqlQueryString);
        ARQ.getContext().setTrue(ARQ.useSAX);

        System.out.println("1");
        QueryExecution qexec = QueryExecutionFactory.sparqlService("http://lsm.deri.ie/sparql", query);
        System.out.println("2");

        //Retrieving the SPARQL Query results
        ResultSet results = qexec.execSelect();
        System.out.println("3");

        //Iterating over the SPARQL Query results
        while (results.hasNext()) {
             QuerySolution soln = results.nextSolution();

             System.out.println("4");
             String SensorID = soln.get("?sensor").toString();
             String lat = soln.get("?lat").toString();
             String lon = soln.get("?lng").toString();

             System.out.println(SensorID);
             System.out.println(lat);
             System.out.println(lon);
        }

        qexec.close();
    }
}

The Problem I am facing is that when I am executing the query, an error is being displayed. The line where the program terminates is the line between 2 and 3. The error displayed is:

Exception in thread "main" java.lang.ClassCastException: java.lang.Long cannot be cast to java.lang.Integer
    at org.apache.http.params.AbstractHttpParams.getIntParameter(AbstractHttpParams.java:70)
    at org.apache.http.client.params.HttpClientParamConfig.getRequestConfig(HttpClientParamConfig.java:54)
    at org.apache.http.impl.client.AbstractHttpClient.doExecute(AbstractHttpClient.java:806)
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:72)
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:57)
    at org.apache.http.impl.client.DecompressingHttpClient.execute(DecompressingHttpClient.java:158)
    at org.apache.http.impl.client.DecompressingHttpClient.execute(DecompressingHttpClient.java:139)
    at org.apache.jena.riot.web.HttpOp.exec(HttpOp.java:1011)
    at org.apache.jena.riot.web.HttpOp.execHttpGet(HttpOp.java:291)
    at org.apache.jena.riot.web.HttpOp.execHttpGet(HttpOp.java:353)
    at com.hp.hpl.jena.sparql.engine.http.HttpQuery.execGet(HttpQuery.java:326)
    at com.hp.hpl.jena.sparql.engine.http.HttpQuery.exec(HttpQuery.java:276)
    at com.hp.hpl.jena.sparql.engine.http.QueryEngineHTTP.execSelect(QueryEngineHTTP.java:346)
    at ExecuteRestClient.main(ExecuteRestClient.java:114)

Is this because the latitude and longitude variable? I am using jena 2.11.

回答1:

What @ZaoTaoBao points to in the comments is likely the source of your problem - https://github.com/pyvandenbussche/sparqles/issues/9

ARQ is not currently using the very latest version of Apache HTTP Client but something in your application/classpath is so the wrong class (from ARQ's point of view) is getting loaded. So when ARQ tries to use the HttpClient API it expects it ends up calling the methods in the new API which no longer have the same type signature and you get the ClassCastException

Edit

So this boils down to a Java/app specific environment problem.

You need to review your class path and/or dependency hierarchy to figure out what else is using Apache HttpClient and resolve the version conflict by not using a version newer than ARQ uses.

mvn dependency:tree is your friend for investigating this on maven projects and then you can use dependency exclusions to remove the newer version. Otherwise you'll need to use whatever dependency/class path management support your IDE or build system provides to investigate this.

However if you are mixing libraries that need multiple versions of HttpClient then doing so is only going to break something else.

回答2:

Long and Integer are two differents classes.

take a look at this:

Integer Long

So you can transform Integer to Long "easily", but Long to Integer you have to do control the exception or if is it possible.

to cast an object to another you can use static methods like: Integer.valueOf(X) or Long.valueOf(X)

I hope it helps.