historymanager.java

dspace 用j2ee架构的一个数字图书馆.开源程序

                        (flag == MODIFY) ? "modify" : "").append(
                        (flag == REMOVE) ? "remove" : "").toString();

        return getUniqueIdInternal(uriPrefix, null, objname, Utils
                .generateHexKey());
    }

    /**
     * Return an RDF property id.
     * 
     * @param objname
     *            The name of an object
     * @param property
     *            The name of a property of the objecty
     * @return The id for the property
     */
    private static String getPropertyId(String objname, String property)
    {
        return getUniqueIdInternal(uriPrefix, null, objname, property);
    }

    /**
     * Return an RDF property id for Harmony property.
     * 
     * @param property
     *            The name of a Harmony property
     * @return The id for the property
     */
    private static String getHarmonyId(String property)
    {
        return getUniqueIdInternal(uriPrefix, null, "harmony", property);
    }

    /**
     * Internal method for id generation.
     * 
     * @param uriPrefix
     *            A URI
     * @param handlePrefix
     * @param objname
     * @param objid
     * @return A unique id
     */
    private static String getUniqueIdInternal(String uriPrefix,
            String handlePrefix, String objname, String objid)
    {
        final String SLASH = "/";

        return new StringBuffer().append(uriPrefix).append(
                uriPrefix.endsWith(SLASH) ? "" : SLASH).append(objname).append(
                objname.endsWith(SLASH) ? "" : SLASH).append(
                (handlePrefix == null) ? "" : handlePrefix).append(
                ((handlePrefix == null) || (handlePrefix.endsWith(SLASH))) ? ""
                        : SLASH).append(objid).toString();
    }

    ////////////////////////////////////////
    // Serialize methods
    ////////////////////////////////////////

    /**
     * Return an RDF stream for this object.
     * 
     * @param context
     *            Current DSpace context
     * @param obj
     *            The object to serialize
     * @return The serialization of the object
     * @exception RDFException
     *                If an error occurs while constructing an RDF graph
     * @exception SQLException
     *                If an error occurs while accessing the database
     */
    private static String serialize(Context context, Object obj)
            throws RDFException, SQLException
    {
        if (obj == null)
        {
            return null;
        }

        Model model = new ModelMem();

        // Add statements about this object
        serializeInternal(context, obj, model);

        StringWriter data = new StringWriter();

        model.write(data);

        // Since this is all in-memory, IOExceptions should never happen
        try
        {
            data.close();
        }
        catch (IOException ioe)
        {
        }

        return data.toString();
    }

    /**
     * Add RDF statements about this object to the model.
     * 
     * @param context
     *            Current DSpace context
     * @param obj
     *            The object to make statements about
     * @param model
     *            The RDF statement graph
     * @exception RDFException
     *                If an error occurs while constructing an RDF graph
     * @exception SQLException
     *                If an error occurs while accessing the database
     */
    private static void serializeInternal(Context context, Object obj,
            Model model) throws RDFException, SQLException
    {
        if (obj == null)
        {
            return;
        }

        String id = getUniqueId(obj);
        Resource res = model.createResource(id);

        //  FIXME Strictly speaking, this is NOT a property of the
        //  object itself, but of the resulting serialization!
        Property generatorId = model.createProperty(uriPrefix + "/generator");

        model.add(res, generatorId, ID);

        if (obj instanceof Community)
        {
            addData(context, (Community) obj, res, model);
        }
        else if (obj instanceof Collection)
        {
            addData(context, (Collection) obj, res, model);
        }
        else if (obj instanceof Item)
        {
            addData(context, (Item) obj, res, model);
        }
        else if (obj instanceof WorkspaceItem)
        {
            addData(context, (WorkspaceItem) obj, res, model);
        }
        else if (obj instanceof WorkflowItem)
        {
            addData(context, (WorkflowItem) obj, res, model);
        }
        else if (obj instanceof EPerson)
        {
            addData(context, (EPerson) obj, res, model);
        }
    }

    /**
     * Serialize and store an object.
     * 
     * @param context
     *            Current DSpace context.
     * @param obj
     *            The object to serialize and store.
     * @return A unique id for the object.
     * @exception RDFException
     *                If an error occurs while constructing an RDF graph
     * @exception IOException
     *                If an error occurs while storing the serialization
     * @exception SQLException
     *                If an error occurs while accessing the database
     */
    private static String doSerialize(Context context, Object obj)
            throws SQLException, IOException, RDFException
    {
        if (obj == null)
        {
            return null;
        }

        String id = getUniqueId(obj);
        String serialization = serialize(context, obj);

        store(context, serialization);

        return id;
    }

    /**
     * Store the serialization (unless it already exists).
     * 
     * @param context
     *            Current DSpace context.
     * @param serialization
     *            The serialization to store.
     * @exception IOException
     *                If an error occurs while storing the serialization
     * @exception SQLException
     *                If an error occurs while accessing the database
     */
    private static void store(Context context, String serialization)
            throws SQLException, IOException
    {
        String checksum = Utils.getMD5(serialization);
        TableRow row = DatabaseManager.findByUnique(context, "history",
                "checksum", checksum);

        // Already stored
        if (row != null)
        {
            return;
        }

        TableRow h = DatabaseManager.create(context, "History");
        int hid = h.getIntColumn("history_id");

        File file = forId(hid, true);
        FileWriter fw = new FileWriter(file);

        fw.write(serialization);
        fw.close();

        h.setColumn("checksum", checksum);
        h.setColumn("creation_date", nowAsTimeStamp());
        DatabaseManager.update(context, h);
    }

    /**
     * Return the last state for the object with id, or null.
     * 
     * @param id
     *            The object's history id
     * @exception SQLException
     *                If an error occurs while accessing the database
     */
    private static String findPreviousState(String id) throws SQLException
    {
        Connection connection = null;
        PreparedStatement statement = null;

        try
        {
            String sql = "SELECT MAX(history_state_id) FROM HistoryState WHERE object_id = ?";

            connection = DatabaseManager.getConnection();
            statement = connection.prepareStatement(sql);
            statement.setString(1, id);

            ResultSet results = statement.executeQuery();

            return results.next() ? results.getString(1) : null;
        }
        finally
        {
            if (statement != null)
            {
                statement.close();
            }

            if (connection != null)
            {
                connection.close();
            }
        }
    }

    ////////////////////////////////////////
    // addData methods
    ////////////////////////////////////////

    /**
     * Add community-specific data to the model.
     * 
     * @param context
     *            Current DSpace context.
     * @param community
     *            The community
     * @param res
     *            RDF resource for the community
     * @param model
     *            The RDF graph
     * @exception RDFException
     *                If an error occurs while constructing an RDF graph
     * @exception SQLException
     *                If an error occurs while accessing the database
     */
    private static void addData(Context context, Community community,
            Resource res, Model model) throws RDFException, SQLException
    {
        String shortname = getShortName(community);
        model.add(res, model.createProperty(getPropertyId(shortname, "ID")),
                community.getID());

        String[] metadata = new String[] { "name", "short_description",
                "introductory_text", "copyright_text", "side_bar_text" };

        for (int i = 0; i < metadata.length; i++)
        {
            String meta = metadata[i];
            addMetadata(model, res, shortname, meta, community
                    .getMetadata(meta));
        }

        Property hasPart = model.createProperty(getHarmonyId("hasPart"));
        Collection[] collections = community.getCollections();

        for (int i = 0; i < collections.length; i++)
        {
            model.add(res, hasPart, getUniqueId(collections[i]));
        }
    }

    /**
     * Add collection-specific data to the model.
     * 
     * @param context
     *            Current DSpace context.
     * @param collection
     *            The collection
     * @param res
     *            RDF resource for the collection
     * @param model
     *            The RDF graph
     * @exception RDFException
     *                If an error occurs while constructing an RDF graph
     * @exception SQLException
     *                If an error occurs while accessing the database
     */
    private static void addData(Context context, Collection collection,
            Resource res, Model model) throws SQLException, RDFException
    {
        String shortname = getShortName(collection);

        model.add(res, model.createProperty(getPropertyId(shortname, "ID")),
                collection.getID());
        model.add(res, model
                .createProperty(getPropertyId(shortname, "license")),
                collection.getLicense());

        String[] metadata = new String[] { "name", "short_description",
                "introductory_text", "copyright_text", "side_bar_text",
                "provenance_description" };

        for (int i = 0; i < metadata.length; i++)
        {
            String meta = metadata[i];
            addMetadata(model, res, shortname, meta, collection
                    .getMetadata(meta));
        }

        Property hasPart = model.createProperty(getHarmonyId("hasPart"));
        ItemIterator items = collection.getItems();

        while (items.hasNext())
        {
            Item item = items.next();

            model.add(res, hasPart, getUniqueId(item));
        }
    }

    /**
     * Add item-specific data to the model.
     * 
     * @param context
     *            Current DSpace context.
     * @param item
     *            The item
     * @param res
     *            RDF resource for the item
     * @param model
     *            The RDF graph
     * @exception RDFException
     *                If an error occurs while constructing an RDF graph
     * @exception SQLException
     *                If an error occurs while accessing the database
     */
    private static void addData(Context context, Item item, Resource res,
            Model model) throws RDFException, SQLException
    {
        DCValue[] dcfields = item.getDC(Item.ANY, Item.ANY, Item.ANY);

        for (int i = 0; i < dcfields.length; i++)
        {
            DCValue dc = dcfields[i];
            String element = dc.element;
            String qualifier = dc.qualifier;

            String type = new StringBuffer().append(element).append(
                    (qualifier == null) ? "" : ".").append(
                    (qualifier == null) ? "" : qualifier).toString();

            Property p = model