cachingolapmodel.java

OLAP 的客户端代码

/*
 * ====================================================================
 * This software is subject to the terms of the Common Public License
 * Agreement, available at the following URL:
 *   http://www.opensource.org/licenses/cpl.html .
 * Copyright (C) 2003-2004 TONBELLER AG.
 * All Rights Reserved.
 * You must accept the terms of that agreement to use this software.
 * ====================================================================
 *
 * 
 */
package com.tonbeller.jpivot.olap.model;

import org.apache.log4j.Logger;

import com.tonbeller.jpivot.core.Model;
import com.tonbeller.jpivot.core.ModelChangeEvent;
import com.tonbeller.jpivot.core.ModelChangeListener;

/**
 * An OlapModel decorator that caches the result
 * 
 * @author av
 */
public class CachingOlapModel extends OlapModelDecorator implements ModelChangeListener {
  private static Logger logger = Logger.getLogger(CachingOlapModel.class);
  Result result = null;  

  /** 
   * invalidates the current result
   */
  public void modelChanged(ModelChangeEvent e) {
    result = null;
  }

	/** 
	 * invalidates the current result
	 */
	public void structureChanged(ModelChangeEvent e) {
		result = null;
	}

  public Result getResult() throws OlapException {
    logger.info("CachingOlapModel: " + ((result == null) ? "getting Result from OLAP Server" : "using cached result"));
    if (result == null) {
      long t1 = System.currentTimeMillis();
      result = super.getResult();
      long t2 = System.currentTimeMillis();
      logger.info("Execute Query took " + (t2 - t1) + " millisec");
    }
    return result;
  }


  /**
   * @see com.tonbeller.jpivot.core.Extension#decorate(Model)
   */
  public Model decorate(Model modelToDecorate) {
    modelToDecorate.addModelChangeListener(this);
    return super.decorate(modelToDecorate);
  }

}