graphrdbmaker.java

jena2.5.4推理机系统的一种最基本实现 HP实验室出品

/*
  (c) Copyright 2003, 2004, 2005, 2006, 2007 Hewlett-Packard Development Company, LP
  [See end of file]
  $Id: GraphRDBMaker.java,v 1.25 2007/01/02 11:50:40 andy_seaborne Exp $
*/

package com.hp.hpl.jena.db.impl;

import com.hp.hpl.jena.db.GraphRDB;
import com.hp.hpl.jena.db.IDBConnection;
import com.hp.hpl.jena.graph.*;
import com.hp.hpl.jena.graph.impl.*;
import com.hp.hpl.jena.shared.*;
import com.hp.hpl.jena.util.CollectionFactory;
import com.hp.hpl.jena.util.iterator.*;
import com.hp.hpl.jena.vocabulary.*;

import java.rmi.server.UID;
import java.util.*;

/**
    A GraphFactory that produces Graphs from database connections. 
    The connection is supplied when the factory is constructed. All the
    created graphs are tracked so that we can supply a removeAll call
    to dispose of them.

    @author kers 
*/

public class GraphRDBMaker extends BaseGraphMaker
    {
    protected IDBConnection c;
    protected Set created = CollectionFactory.createHashedSet();
    int reificationStyle;
    
    /**
        Construct a new GraphRDB factory based on the supplied DB connection.
        @param c the database connection
    */
    public GraphRDBMaker( IDBConnection c, ReificationStyle style ) 
        {
        super( style ); 
        this.c = c; 
        this.reificationStyle = GraphRDB.styleRDB( style );
        }

    /**
        Answer the RDFS class of this RDB GraphMaker
        @return JenaModelSpec.RDBMakerClass [as node]
    */
    public Node getMakerClass()
        { return JenaModelSpec.RDBMakerSpec.asNode(); }
        
    /**
        Augment the maker description of this maker with RDB-specific properties.
        TODO do this
    */     
    protected void augmentDescription( Graph g, Node self )
        {}
        
    /**
        Answer the default graph of this Maker; make it if necessary.
    */
    public Graph getGraph()
        { if (defaultGraph == null) 
            defaultGraph = consGraph( null, !c.containsDefaultModel() ); 
         return defaultGraph; }
        
    /**
        The default graph for this maker, or null if there isn't one.
    */
    protected Graph defaultGraph = null;
    
    public Graph openGraph()
        { 
        if (defaultGraph != null)
            return defaultGraph;
        if (c.containsDefaultModel())
            return defaultGraph = consGraph( null, false );
        throw new DoesNotExistException( "no default graph in this GraphMaker" );
        }
    
    /**
        Answer an "anonymous", freshly-created graph. We fake this by creating 
        a graph with the name "anon_"+UID().toString. This may lead to problems 
        later; eg such a graph may need to be deleted when the connection is 
        closed.
        
        TODO resolve this issue.
    */
    public Graph createGraph()
        { return createGraph( freshGraphName(), false ); }

    /**
        Answer a freshly-synthesised "anonymous" name.
    */
    public String freshGraphName()
        { return "anon_" + new UID().toString(); }
    
    /**
     	Create an RDB graph and remember its name.
     */
    public Graph createGraph( String name, boolean strict )
        {
        created.add( name );
        boolean fresh = strict || !hasGraph( name );
        return consGraph( name, fresh );
        }
    
    /**
        Open an existing graph; if there's no such graph, but failIfAbsent is
        false, create a new one. In any case, return that graph.
    */
    public Graph openGraph( String name, boolean strict )
        {
        boolean fresh = hasGraph( name ) == false && strict == false;
        if (fresh) created.add( name );
        return consGraph( name, fresh );
        }
        
    protected Graph consGraph( String name, boolean fresh )
        {        
        Graph p = c.getDefaultModelProperties().getGraph();
        return new GraphRDB( c, name, (fresh ? p : null), reificationStyle, fresh );
        }
        
    /**
     	Remove a graph from the database - at present, this has to be done by
        opening it first.
        
    */
    public void removeGraph( String name )
        {
        GraphRDB toDelete = (GraphRDB) openGraph( name, true );
        toDelete.remove();
        toDelete.close();
        created.remove( name );
        }
        
    /**
        Return true iff there's a graph with the given name.
    */
    public boolean hasGraph( String name )
        { return c.containsModel( name ); }
        
    /**
        Remove all the graphs that have been created by this factory.
    */
    public void removeAll()
        {
        Iterator it = CollectionFactory.createHashedSet( created ).iterator();
        while (it.hasNext()) removeGraph( (String) it.next() );
        }
        
    public void close()
        { /* should consider - do we close the connection or not? */ }
        
    public ExtendedIterator listGraphs()
        { return c.getAllModelNames() .filterDrop ( filterDEFAULT ); }
        
    private Filter filterDEFAULT = new Filter()
        { public boolean accept( Object x ) { return "DEFAULT".equals( x ); } };
    }

/*
    (c) Copyright 2002, 2003, 2004, 2005, 2006, 2007 Hewlett-Packard Development Company, LP
    All rights reserved.

    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions
    are met:

    1. Redistributions of source code must retain the above copyright
       notice, this list of conditions and the following disclaimer.

    2. Redistributions in binary form must reproduce the above copyright
       notice, this list of conditions and the following disclaimer in the
       documentation and/or other materials provided with the distribution.

    3. The name of the author may not be used to endorse or promote products
       derived from this software without specific prior written permission.

    THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
    IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
    OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
    IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
    NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
    DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
    THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
    (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
    THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/