Metacat

/**

 *  '$RCSfile$'

 *    Purpose: A Class that searches a relational DB for elements and

 *             attributes that have free text matches a query string,

 *             or structured query matches to a path specified node in the

 *             XML hierarchy.  It returns a result set consisting of the

 *             document ID for each document that satisfies the query

 *  Copyright: 2000 Regents of the University of California and the

 *             National Center for Ecological Analysis and Synthesis

 *    Authors: Matt Jones

 *

 *   '$Author: berkley $'

 *     '$Date: 2007-04-02 15:23:45 -0700 (Mon, 02 Apr 2007) $'

 * '$Revision: 3219 $'

 *

 * 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

 */

package edu.ucsb.nceas.metacat;

import java.io.*;

import java.util.*;

import org.w3c.dom.*;

import org.apache.xpath.*;

import org.apache.log4j.Logger;

/**

 * this class implements a metacat resultset and can be serialized to xml

 * for printing to the servlet output stream.

 */

public class MetacatResultSet

{

  private Logger log = Logger.getLogger(MetacatResultSet.class);

  private Vector results = new Vector();

  /**

   * default constructor

   */

  public MetacatResultSet()

  {

  }

  /**

   * constructor that can process a dom.  this is very slow.

   */

  public MetacatResultSet(Document d)

    throws Exception

  {

    log.warn("processing resultset...");

    NodeList nl = XPathAPI.selectNodeList(d, "//document");

    for(int i=0; i<nl.getLength(); i++)

    { //get each of the document nodes

      Node docNode = nl.item(i);

      Node docidNode = XPathAPI.selectSingleNode(docNode, "./docid");

      log.warn("processing " + docidNode.getFirstChild().getNodeValue());

      Node docnameNode = XPathAPI.selectSingleNode(docNode, "./docname");

      Node doctypeNode = XPathAPI.selectSingleNode(docNode, "./doctype");

      Node createdateNode = XPathAPI.selectSingleNode(docNode, "./createdate");

      Node updatedateNode = XPathAPI.selectSingleNode(docNode, "./updatedate");

      //process the returnfields

      NodeList returnfieldNL = XPathAPI.selectNodeList(docNode, "./param");

      Hashtable returnfieldHash = new Hashtable();

      for(int j=0; j<returnfieldNL.getLength(); j++)

      {

        Node returnfieldNode = returnfieldNL.item(j);

        Node nameNode = XPathAPI.selectSingleNode(returnfieldNode, "@name");

        String value = returnfieldNode.getFirstChild().getNodeValue();

        String name = nameNode.getNodeValue();

        returnfieldHash.put(name, value);

      }

      Result r = new Result(docidNode.getFirstChild().getNodeValue(),

                            docnameNode.getFirstChild().getNodeValue(),

                            doctypeNode.getFirstChild().getNodeValue(),

                            createdateNode.getFirstChild().getNodeValue(),

                            updatedateNode.getFirstChild().getNodeValue(),

                            returnfieldHash);

      addResult(r);

    }

  }

  /**

   * add a new result to the resultSet

   */

  public void addResult(Result r)

  {

    results.addElement(r);

  }

  /**

   * returns a vector of the results

   */

  public Vector getResults()

  {

    return results;

  }

  /**

   * serialize a selection of the results.  This will print the results from

   * start to end-1.  if end is 0, nothing will be printed.

   */

  public String serializeToXML(int start, int end)

  {

    StringBuffer sb = new StringBuffer();

    if(start > results.size() || end > results.size())

    { //make sure we don't go over the edge of the vector

      start = results.size() - 10;

      end = results.size();

    }

    for(int i=start; i<end; i++)

    {

      Result r = (Result)results.elementAt(i);

      sb.append(r.toString());

      sb.append("\n");

    }

    return sb.toString();

  }

  /**

   * returns an xml representation of this object

   */

  public String toString()

  {

    StringBuffer sb = new StringBuffer();

    for(int i=0; i<results.size(); i++)

    {

      Result r = (Result)results.elementAt(i);

      sb.append(r.toString());

      sb.append("\n");

    }

    return sb.toString();

  }

  /**

   * a class to store one result

   */

  public class Result

  {

    private String docid;

    private String docname;

    private String doctype;

    private String createDate;

    private String updateDate;

    private Hashtable returnfields;

    /**

     * constructor

     */

    public Result(String docid, String docname, String doctype, 

      String createDate, String updateDate, Hashtable returnfields)

    {

      this.docid = docid;

      this.doctype = doctype;

      this.createDate = createDate;

      this.updateDate = updateDate;

      this.returnfields = returnfields;

    }

    /**

     * returns serialized version of this result

     */

    public String toString()

    {

      StringBuffer sb = new StringBuffer();

      sb.append("<document>\n");

      sb.append("  <docid>" + docid + "</docid>\n");

      sb.append("  <docname>" + docname + "</docname>\n");

      sb.append("  <doctype>" + doctype + "</doctype>\n");

      sb.append("  <createdate>" + createDate + "</createdate>\n");

      sb.append("  <updatedate>" + updateDate + "</updatedate>\n");

      Enumeration keys = returnfields.keys();

      while(keys.hasMoreElements())

      {

        String key = (String)keys.nextElement();

        String value = (String)returnfields.get(key);

        sb.append("  <param name=\"" + key + "\">" + value + "</param>\n");

      }

      sb.append("</document>");

      return sb.toString();

    }

  }

}