metasearcher.java.svn-base

由国外的一个著名的geonetwork修改而来

//===	Copyright (C) 2001-2005 Food and Agriculture Organization of the
//===	United Nations (FAO-UN), United Nations World Food Programme (WFP)
//===	and United Nations Environment Programme (UNEP)
//===
//===	This program is free software; you can redistribute it and/or modify
//===	it under the terms of the GNU General Public License as published by
//===	the Free Software Foundation; either version 2 of the License, or (at
//===	your option) any later version.
//===
//===	This program is distributed in the hope that it will be useful, but
//===	WITHOUT ANY WARRANTY; without even the implied warranty of
//===	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
//===	General Public License for more details.
//===
//===	You should have received a copy of the GNU General Public License
//===	along with this program; if not, write to the Free Software
//===	Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
//===
//===	Contact: Jeroen Ticheler - FAO - Viale delle Terme di Caracalla 2,
//===	Rome - Italy. email: [e-mail]
//==============================================================================

package org.fao.geonet.kernel.search;

import org.fao.geonet.services.util.MainUtil;
import org.fao.geonet.constants.Geonet;
import org.fao.geonet.constants.Params;

import jeeves.server.*;
import jeeves.server.context.*;
import jeeves.utils.Util;

import org.jdom.Element;

import java.util.Iterator;

//--------------------------------------------------------------------------------
// interface to search metadata
//--------------------------------------------------------------------------------

public abstract class MetaSearcher
{
	private int     _from, _to;
	private boolean _valid = false;
	
	//--------------------------------------------------------------------------------
	// MetaSearcher API

	public abstract void search(ServiceContext srvContext, Element request, ServiceConfig config) throws Exception;

	public abstract Element present(ServiceContext srvContext, Element request, ServiceConfig config) throws Exception;

	public abstract int getSize();

	public abstract Element getSummary() throws Exception;

	public abstract void close();
	
	//--------------------------------------------------------------------------------
	// utilities
	
	public void setValid(boolean valid)
	{
		_valid = valid;
	}
	
	protected void initSearchRange(ServiceContext srvContext)
	{
		// get from and to default values
		_from = 1;
		Element defaultSearch = MainUtil.getDefaultSearch(srvContext, null);
		try
		{
			_to = Integer.parseInt(defaultSearch.getChildText(Geonet.SearchResult.HITS_PER_PAGE));
		}
		catch (NumberFormatException nfe)
		{
			_to = 10;
		}
	}
	
	protected void updateSearchRange(Element request)
	{
		// get request parameters
		String sFrom = request.getChildText("from");
		String sTo   = request.getChildText("to");
		if (sFrom != null)
		{
			try { _from = Integer.parseInt(sFrom); }
			catch (NumberFormatException nfe) { throw new IllegalArgumentException("Bad 'from' parameter: " + sFrom); }
		}
		if (sTo != null)
		{
			try { _to = Integer.parseInt(sTo); }
			catch (NumberFormatException nfe) { throw new IllegalArgumentException("Bad 'to' parameter: " + sTo); }
		}

		int count = getSize();
		_from      = _from > count ? count : _from;
		_to        = _to   > count ? count : _to;
	}
	
	protected int getFrom()     { return _from; }
	protected int getTo()       { return _to; }
	protected boolean isValid() { return _valid; }

	public Element get(ServiceContext srvContext, Element request, ServiceConfig config) throws Exception
	{
		String id = Util.getParam(request, Params.ID);
		
		// save _from and _to
		int from = _from;
		int to   = _to;
		
		// perform search
		Element req = new Element("request");
		addElement(req, "from", id);
		addElement(req, "to",   id);
		Element result = present(srvContext, req, config);

		// restore _from and _to
		_from = from;
		_to   = to;
		
		// skip summary
		for (Iterator iter = result.getChildren().iterator(); iter.hasNext(); )
		{
			Element child = (Element) iter.next();

			if (!child.getName().equals(Geonet.Elem.SUMMARY))
				return child;
		}
		return null;
	}
	
	protected static void addElement(Element root, String name, String value)
	{
		root.addContent(new Element(name).setText(value));
	}
}