integralset.java

来自「这是一个以JAVA编写的程序,本人还没有试过,是一个简单的温度控制系统」· Java 代码 · 共 90 行

package net.sf.dz.controller;

import java.util.Iterator;
import java.util.NoSuchElementException;

/**
 * Data set supporting the integration calculation.
 *
 * <p>
 *
 * The {@link DataSet#record record()} method from {@link DataSet DataSet}
 * class is used, however, make sure you record the right values. If this
 * class is used for the {@link PID_Controller PID controller}, it must be
 * fed with controller error, and anti-windup action must be programmed
 * outside of this class.
 *
 * @author Copyright &copy; <a href="mailto:[e-mail]"> Vadim Tkachenko</a> 2001-2002
 * @version $Id: IntegralSet.java,v 1.3 2004/06/28 20:35:46 vtt Exp $
 */
public class IntegralSet extends DataSet {

    /**
     * Create the instance.
     *
     * @param integrationTime Integration time, milliseconds. Data elements
     * older than this are expired.
     */
    public IntegralSet(final long integrationTime) {

        super(integrationTime);
    }

    /**
     * Get the integral starting with the first data element available and
     * ending with the last data element available.
     *
     * <p>
     *
     * Integration time must have been taken care of by {@link
     * DataSet#expire expiration}.
     *
     * @return An integral value.
     */
    public final double getIntegral() {

        double result = 0;

        long startTime = System.currentTimeMillis();

        try {

            // The following line will throw the NoSuchElementException if
            // the dataSet is empty. It is possible to check the size, but
            // handling the exception is more efficient because happens just
            // once - at the startup, or when there was an interruption in
            // the data sequence longer than the expiration interval and all
            // the data elements were expired.

            Iterator i = iterator();
            Long trailerKey = (Long) i.next();

            while (i.hasNext()) {

                double trailerValue = get(trailerKey.longValue());
                Long currentKey = (Long) i.next();
                double currentValue = get(currentKey.longValue());

                double diff = ((currentValue + trailerValue) / 2) * (currentKey.longValue() - trailerKey.longValue());

                result += diff;

                trailerKey = currentKey;
            }

            return result;

        } catch (NoSuchElementException nseex) {

            System.err.println("Ignored:");
            nseex.printStackTrace();

            return result;

        } finally {

            //System.err.println("getIntegral@" + hashCode() + "," + dataSet.size() + ": " + (System.currentTimeMillis() - startTime));
        }
    }
}