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    >> 本版讨论Semantic Web(语义Web,语义网或语义万维网, Web 3.0)及相关理论,如:Ontology(本体,本体论), OWL(Web Ontology Langauge,Web本体语言), Description Logic(DL, 描述逻辑),RDFa,Ontology Engineering等。
    [返回] W3CHINA.ORG讨论区 - 语义网·描述逻辑·本体·RDF·OWLW3CHINA.ORG讨论区 - Web新技术讨论『 Semantic Web(语义Web)/描述逻辑/本体 』 → owl2prefuse如何遍历本体实例? 查看新帖用户列表

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     * 贴子主题: owl2prefuse如何遍历本体实例? 举报  打印  推荐  IE收藏夹 
       本主题类别: Ontology Language | RDF/RDFS    
     yfhbwh 帅哥哟,离线,有人找我吗?
      
      
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    发贴心情 owl2prefuse如何遍历本体实例?

    Animals本体:
    <?xml version="1.0"?>
    <rdf:RDF
        xmlns="http://localhost/Animals.owl#"
        xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
        xmlns:xsd="http://www.w3.org/2001/XMLSchema#"
        xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
        xmlns:owl="http://www.w3.org/2002/07/owl#"
      xml:base="http://localhost/Animals.owl">
      <owl:Ontology rdf:about=""/>
      <owl:Class rdf:about="#Animals">
          <rdfs:label rdf:datatype="http://www.w3.org/2001/XMLSchema#string"
          >动物</rdfs:label>
      </owl:Class>
      <owl:Class rdf:ID="Herbivores">
        <rdfs:subClassOf>
          <owl:Class rdf:ID="Animals"/>
        </rdfs:subClassOf>
        <rdfs:label rdf:datatype="http://www.w3.org/2001/XMLSchema#string"
        >食草动物</rdfs:label>
      </owl:Class>
      <owl:Class rdf:ID="Predators">
        <rdfs:subClassOf>
          <owl:Class rdf:ID="Animals"/>
        </rdfs:subClassOf>
        <rdfs:label rdf:datatype="http://www.w3.org/2001/XMLSchema#string"
        >食肉动物</rdfs:label>
      </owl:Class>
      <owl:DatatypeProperty rdf:ID="age">
        <rdfs:label rdf:datatype="http://www.w3.org/2001/XMLSchema#string"
        >年龄</rdfs:label>
        <rdfs:domain rdf:resource="#Animals"/>
        <rdfs:range rdf:resource="http://www.w3.org/2001/XMLSchema#int"/>
      </owl:DatatypeProperty>
      <owl:DatatypeProperty rdf:ID="weight">
        <rdfs:label rdf:datatype="http://www.w3.org/2001/XMLSchema#string"
        >重量</rdfs:label>
        <rdfs:domain rdf:resource="#Animals"/>
        <rdfs:range rdf:resource="http://www.w3.org/2001/XMLSchema#int"/>
      </owl:DatatypeProperty>
      <Predators rdf:ID="_00001">
        <rdfs:label rdf:datatype="http://www.w3.org/2001/XMLSchema#string"
        >狮子</rdfs:label>
        <age rdf:datatype="http://www.w3.org/2001/XMLSchema#int"
        >10</age>
        <weight rdf:datatype="http://www.w3.org/2001/XMLSchema#int"
        >500</weight>
      </Predators>
    </rdf:RDF>

    converter类读取本体文件
    public class Converter
    {
     protected OntModel m_model;
     
     public Converter(String p_OWLFile)
     {
      load(p_OWLFile);
     }
     
     private void load(String p_OWLFile)
     {
      m_model = ModelFactory.createOntologyModel(OntModelSpec.OWL_MEM);
      
      InputStream in = FileManager.get().open(p_OWLFile);
      
      if(in == null)
      {
       throw new IllegalArgumentException("File: " + p_OWLFile + "not found!");
      }
      
      m_model.read(in, "");
     }
    }

    OWLGraphConverter画图
    public class OWLGraphConverter extends Converter
    {
        /**
         * The created Prefuse graph.
         */
        private Graph m_graph;
        
        /**
         * An ArrayList containing all the edges that have to be added to the Prefuse
         * graph.
         */
        private ArrayList<String[]> m_edges;
        
        /**
         * An Hashtable containing all the nodes in Prefuse graph.
         */
        private Hashtable<String, Node> m_nodes;
        
        /**
         * An ArrayList containing the URI's of OWL classes that should not be converted
         * into the Prefuse graph.
         */
        private ArrayList<String> m_uselessType;
        
        
        /**
         * Creates a new instance of OWLGraphConverter
         * @param p_OWLFile The path to the OWL file that needs to be converted.
         * @param p_directed A boolean indicating whether the Prefuse graph needs to
         * be directed.
         */
        public OWLGraphConverter(String p_OWLFile, boolean p_directed)
        {
            super(p_OWLFile);
            init(p_directed);
        }
        
        /**
         * Initialize the graph converter.
         * @param p_directed A boolean indicating whether the Prefuse graph needs to
         * be directed.
         */
        private void init(boolean p_directed)
        {
            m_edges = new ArrayList<String[]>();
            m_nodes = new Hashtable<String, Node>();
            
            // Create an ArrayList which contains URI's of nodes we do not want to
            // visualize, because they are to general.
            m_uselessType = new ArrayList<String>();
            m_uselessType.add("http://www.w3.org/2002/07/owl#Class");
            m_uselessType.add("http://www.w3.org/2000/01/rdf-schema#Class");
            
            // Create the graph.
            createGraph(p_directed);
        }
        
        /**
         * Return the created Prefuse graph.
         * @return The created Prefuse graph.
         */
        public Graph getGraph()
        {
            return m_graph;
        }
        
        /**
         * Create the Prefuse graph. This method creates an empty graph and adds the
         * appropriate columns to the node- and edgestable. After that it gets the root
         * class (owl:Thing) of the OWL graph and recursively starts building the graph
         * from there.
         * This method is automatically called from the constructors of this converter.
         * @param p_directed A boolean indicating whether the Prefuse graph needs to
         * be directed.
         */
        private void createGraph(boolean p_directed)
        {
            // Create a new empty graph.
            m_graph = new Graph(p_directed);
            
            // Add the appropriate columns.
            m_graph.getNodeTable().addColumn("URI", String.class);
            m_graph.getNodeTable().addColumn("name", String.class);
            m_graph.getNodeTable().addColumn("type", String.class);
            m_graph.getEdgeTable().addColumn("label", String.class);
            
            // Get the root node.
            OntClass rootClass = m_model.getOntClass("http://localhost/Animals.owl#Animals");
            // Build the entire tree.
            buildGraph(rootClass);
            
            // All the edges are stored in an ArrayList, because they can only be added
            // if all the appropriate nodes exist. At this point this is the case, so
            // all the nodes are created.
            createEdges();
        }
        
        /**
         * Build the Prefuse graph, this method is called recursively.
         * @param p_currentClass The class which is being added to the graph.
         */
        private void buildGraph(OntClass p_currentClass)
        {
            // If there is no root node yet, one is created.
            Node currNode = m_graph.addNode();
            currNode.setString("URI", p_currentClass.getURI());
            currNode.setString("name", p_currentClass.getLocalName());
            currNode.setString("type", "class");
            
            // Walk trough the subclasses of the current class.
            ExtendedIterator itClasses = p_currentClass.listSubClasses(true);
            while(itClasses.hasNext())
            {
                 //Recurse trough the subclasses of the current node.
                buildGraph((OntClass) itClasses.next());
            }
            
            // Walk trough the instances of the current class.
            ExtendedIterator itIndividuals = p_currentClass.listInstances();
            while(itIndividuals.hasNext())
            {
                Individual foundIndividual = (Individual) itIndividuals.next();
                if (foundIndividual.getURI() != null)
                {
                    // Create the node for this instance.
                    Node node = m_graph.addNode();
                    node.setString("URI", foundIndividual.getURI());
                    node.setString("name", foundIndividual.getLocalName());
                    node.setString("type", "individual");
                
                    // Add this node to the nodes ArrayList.
                    m_nodes.put(foundIndividual.getURI(), node);

                    // Add the edges, connected to this node, to the edges ArrayList.
                    storeEdges(foundIndividual);
                }
            }
            
            // Add this node to the nodes ArrayList.
            m_nodes.put(p_currentClass.getURI(), currNode);
            
            // Add the edges, connected to this node, to the edges ArrayList.
            storeEdges(p_currentClass);
        }
        
        /**
         * Temporarily store the edges which need to be added the graph. All the edges
         * are stored in an ArrayList, because they can only be added if all the
         * appropriate nodes exist. At this point this is the case, so all the nodes
         * are created.
         * @param p_resource The Jena OntResource of which the edges need to be stored.
         */
        private void storeEdges(OntResource p_resource)
        {
            String sourceURI = p_resource.getURI();
            
            if (!m_uselessType.contains(sourceURI))
            {
                StmtIterator itProperties = p_resource.listProperties();
                while (itProperties.hasNext())
                {
                    Statement property = itProperties.nextStatement();
                    String localName = property.getPredicate().getLocalName();

                    if (property.getObject().isResource())
                    {
                        String targetURI = ((Resource) property.getObject()).getURI();
                        if (!m_uselessType.contains(targetURI) && targetURI != null)
                        {
                            String[] edge = new String[3];
                            edge[0] = sourceURI;
                            edge[1] = localName;
                            edge[2] = targetURI;
                            m_edges.add(edge);
                        }
                    }
                }
            }
        }
        
        /**
         * Create edges for the relevant properties of the resource.
         */
        private void createEdges()
        {
            for (int i = 0; i < m_edges.size(); i++)
            {
                String[] strEdge = m_edges.get(i);
                
                // Get the source and the target node.
                Node source = m_nodes.get(strEdge[0]);
                Node target = m_nodes.get(strEdge[2]);
                
                Edge edge = m_graph.addEdge(source, target);
                edge.setString("label", strEdge[1]);
            }
        }
    }

    最后由主程序调用

    OWLGraphConverter类实际上就是一个递归运算,遍历本体的所有类和实例,而根目录就是:
    OntClass rootClass = m_model.getOntClass("http://localhost/Animals.owl#Animals");

    问题是我把这句改成:
    Individual individual = m_model.getIndividual("http://localhost/Animals.owl#_00001");
    删掉显示类的语句,只显示以_00001实例为根目录的所有属性,报空指针错:
    Exception in thread "main" java.lang.NullPointerException
     at owl2prefuse.graph.OWLGraphConverter.buildGraph(OWLGraphConverter.java:127)
     at owl2prefuse.graph.OWLGraphConverter.createGraph(OWLGraphConverter.java:111)
     at owl2prefuse.graph.OWLGraphConverter.init(OWLGraphConverter.java:76)
     at owl2prefuse.graph.OWLGraphConverter.<init>(OWLGraphConverter.java:55)
     at Demo.<init>(Demo.java:30)
     at Demo.main(Demo.java:50)

    不知道为什么,急啊,望各位高手不吝赐教啊!!!


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    点击查看用户来源及管理<br>发贴IP:*.*.*.* 2009-6-15 9:24:00
     
     iamwym 帅哥哟,离线,有人找我吗?
      
      
      
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    发贴心情 
    你搞了好像太复杂了吧,用个树就可以了,不一定需要用图
    点击查看用户来源及管理<br>发贴IP:*.*.*.* 2009-6-15 11:14:00
     
     yfhbwh 帅哥哟,离线,有人找我吗?
      
      
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    发贴心情 
    我也想用树啊
    可是导师说了要用图表示
    我也没办法啊
    点击查看用户来源及管理<br>发贴IP:*.*.*.* 2009-6-15 19:02:00
     
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