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The Waikato Environment for Knowledge Analysis (WEKA), a machine learning workbench. This is the stable version. Apart from bugfixes, this version does not receive any other updates.
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/*
 *    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., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

/*
 *    DatabaseResultListener.java
 *    Copyright (C) 1999 University of Waikato, Hamilton, New Zealand
 *
 */


package weka.experiment;

import weka.core.FastVector;
import weka.core.RevisionUtils;

import java.sql.DatabaseMetaData;
import java.sql.ResultSet;

/**
 
 * Takes results from a result producer and sends them to a database.
 * 
 
 * 
 * @author Len Trigg ([email protected])
 * @version $Revision: 5125 $
 */
public class DatabaseResultListener 
  extends DatabaseUtils
  implements ResultListener {

  /** for serialization */
  static final long serialVersionUID = 7388014746954652818L;  
  
  /** The ResultProducer to listen to */
  protected ResultProducer m_ResultProducer;
  
  /** The name of the current results table */
  protected String m_ResultsTableName;

  /** True if debugging output should be printed */
  protected boolean m_Debug = true;

  /** Holds the name of the key field to cache upon, or null if no caching */
  protected String m_CacheKeyName = "";

  /** Stores the index of the key column holding the cache key data */
  protected int m_CacheKeyIndex;

  /** Stores the key for which the cache is valid */
  protected Object [] m_CacheKey;

  /** Stores the cached values */
  protected FastVector m_Cache = new FastVector();


  /**
   * Returns a string describing this result listener
   * @return a description of the result listener suitable for
   * displaying in the explorer/experimenter gui
   */
  public String globalInfo() {
    return "Takes results from a result producer and sends them to a "
      +"database.";
  }

  /**
   * Sets up the database drivers
   *
   * @throws Exception if an error occurs
   */
  public DatabaseResultListener() throws Exception {

    super();
  }

  /**
   * Prepare for the results to be received.
   *
   * @param rp the ResultProducer that will generate the results
   * @throws Exception if an error occurs during preprocessing.
   */
  public void preProcess(ResultProducer rp) throws Exception {

    m_ResultProducer = rp;
    // Connect to the database and find out what table corresponds to this
    //   ResultProducer
    updateResultsTableName(m_ResultProducer);
  }
  
  /**
   * Perform any postprocessing. When this method is called, it indicates
   * that no more results will be sent that need to be grouped together
   * in any way.
   *
   * @param rp the ResultProducer that generated the results
   * @throws Exception if an error occurs
   */
  public void postProcess(ResultProducer rp) throws Exception {

    if (m_ResultProducer != rp) {
      throw new Error("Unrecognized ResultProducer calling postProcess!!");
    }
    disconnectFromDatabase();
  }
  
  /**
   * Determines if there are any constraints (imposed by the
   * destination) on any additional measures produced by
   * resultProducers. Null should be returned if there are NO
   * constraints, otherwise a list of column names should be
   * returned as an array of Strings. In the case of
   * DatabaseResultListener, the structure of an existing database
   * will impose constraints.
   * @param rp the ResultProducer to which the constraints will apply
   * @return an array of column names to which resutltProducer's
   * results will be restricted.
   * @throws Exception if an error occurs.
   */
  public String [] determineColumnConstraints(ResultProducer rp) 
    throws Exception {
    FastVector cNames = new FastVector();
    updateResultsTableName(rp);
    DatabaseMetaData dbmd = m_Connection.getMetaData();
    ResultSet rs;
    // gets a result set where each row is info on a column
    if (m_checkForUpperCaseNames) {
      rs = dbmd.getColumns(null, null, m_ResultsTableName.toUpperCase(), null);
    } else {
      rs = dbmd.getColumns(null, null, m_ResultsTableName, null);
    }
    boolean tableExists=false;
    int numColumns = 0;
   
    while (rs.next()) {
      tableExists = true;
      // column four contains the column name
      String name = rs.getString(4);
      if (name.toLowerCase().startsWith("measure")) {
	numColumns++;
	cNames.addElement(name);
      }
    }

    // no constraints on any additional measures if the table does not exist
    if (!tableExists) {
      return null;
    }

    // a zero element array indicates maximum constraint
    String [] columnNames = new String [numColumns];
    for (int i=0;i