source: tmcsimulator/trunk/src/tmcsim/paramicscommunicator/ParamicsFileReader.java @ 25

package tmcsim.paramicscommunicator;



import java.io.File;

import java.io.FileReader;

import java.io.FileWriter;

import java.io.IOException;

import java.util.Observable;

import java.util.Timer;

import java.util.TimerTask;

import java.util.logging.Level;

import java.util.logging.Logger;

import javax.xml.parsers.DocumentBuilderFactory;

import org.w3c.dom.Document;

import org.w3c.dom.Element;

import tmcsim.common.CADProtocol.PARAMICS_ACTIONS;

import tmcsim.common.CADProtocol.PARAMICS_COMM_TAGS;

import tmcsim.paramicscommunicator.FileIOUpdate.IO_TYPE;



/**

 * The ParamicsFileReader handles reading fom a target file which is written to

 * by Paramics. Once initialized, a timer task is started which periodically

 * checks the target file for updates. If the file has been modified, it is read

 * and cleared. The read data is transmitted to the CAD Simulator.

 *

 * @author Matthew Cechini

 * @version 0.1 Notes by jdalbey: Paramics modeler is licensed third-party

 * software and apparently we don't have an SDK for it. So it seems the

 * workaround was to communicate with it via data files that the modeler

 * produces. Wacky, but it works for now. Look at the run() method below: if

 * (lastModified < inputFile.lastModified()) Means it's watching the file to

 * see if it has been updated by the modeler.

 */

public class ParamicsFileReader extends Observable

{



    /**

     * Error Logger.

     */

    private Logger paramLogger = Logger.getLogger("tmcsim.paramicscommunicator");

    /**

     * FileReader ID used for creation of the ParamicsCommMessage

     */

    private String readerID = null;

    /**

     * File reference to the file where data is read.

     */

    private File inputFile = null;

    /**

     * FileReader used to read data from the input file.

     */

    private FileReader fileReader = null;

    /**

     * FileWriter used to clear the input file.

     */

    private FileWriter fileWriter = null;

    /**

     * Value (seconds since 1/1/1970) of input file's last modification time.

     */

    private long lastModified = 0;

    /**

     * Timer used to schedule file reading tasks.

     */

    private Timer readerTimer = null;

    /**

     * Duration (in seconds) that the TimerTask will be scheduled to read from

     * the target file.

     */

    private long readerInterval;



    /**

     * A TimerTask to read from the target file. If the file has been modified

     * since last read, read the file and transmit the data to the CAD

     * Simulator.

     *

     * @author Matthew Cechini

     */

    private class ReaderTimerTask extends TimerTask

    {



        public void run()

        {

            paramLogger.logp(Level.INFO,

                    "ParamicsFileReader.ReaderTimerTask", "run()",

                    "Waiting for " + inputFile + " to be modified.");

            if (lastModified < inputFile.lastModified())

            {

                paramLogger.logp(Level.INFO,

                        "ParamicsFileReader.ReaderTimerTask", "run()",

                        "Cool, " + inputFile + " has been modified, let's read it.");



                try

                {

                    Document readerDoc = DocumentBuilderFactory.newInstance()

                            .newDocumentBuilder().newDocument();



                    Element readerElem = readerDoc.createElement(PARAMICS_COMM_TAGS.READER.tag);

                    readerElem.setAttribute(PARAMICS_COMM_TAGS.ID.tag, readerID);

                    readerElem.setAttribute(PARAMICS_COMM_TAGS.ACTION.tag,

                            PARAMICS_ACTIONS.READ_FILE.action);



                    Element messageElem = readerDoc.createElement(PARAMICS_COMM_TAGS.MESSAGE.tag);

                    String fileContents = readFromFile();

                    paramLogger.logp(Level.INFO,

                            "ParamicsFileReader.ReaderTimerTask", "run()",

                            "Nice, we read " + fileContents);

                    messageElem.appendChild(readerDoc.createTextNode(fileContents));

                    readerElem.appendChild(messageElem);



                    readerDoc.appendChild(readerElem);



                    setChanged();

                    notifyObservers(readerDoc);

                } catch (Exception e)

                {

                    paramLogger.logp(Level.SEVERE,

                            "ParamicsFileReader.ReaderTimerTask", "run()",

                            "Exception in reading from file: "

                            + inputFile.getName(), e);

                }

            }

        }

    }



    /**

     * Constructor. Set the reader id and interval from the parsed

     * ParamicsCommMessage. The interval is found within the first three

     * characters of the object's "message" data member. Create a file object

     * for the target file, and create a new file if it does not already exist.

     * Instantiate the timer and ReaderTimerTask to begin periodic reading of

     * the file.

     *

     * @param workingDir Target working directory. // Oops, the following seem

     * obsolete

     * @param mess ParamicsCommMessage object containing registration data.

     * @param theComm Reference to the ParamicsCommunicator.

     */

    public ParamicsFileReader(String workingDir, String id, Integer interval, String targetFile)

    {



        try

        {

            readerID = id;

            readerInterval = interval;



            inputFile = new File(workingDir + targetFile);



            if (!inputFile.exists())

            {

                inputFile.createNewFile();

            }



            readerTimer = new Timer();

            readerTimer.scheduleAtFixedRate(new ReaderTimerTask(),

                    0L, readerInterval * 1000);



        } catch (IOException ioe)

        {

            paramLogger.logp(Level.SEVERE, "ParamicsFileReader",

                    "Constructor()", "Exception in initializing file reading.", ioe);

        }

    }



    /**

     * Method opens the target file and reads all contents. The file is then

     * cleared.

     *

     * @returns

     * @throws IOException if there is an error in reading or writing to the

     * file.

     */

    private String readFromFile() throws IOException

    {



        char[] input = new char[(int) inputFile.length()];



        fileReader = new FileReader(inputFile);

        fileReader.read(input);

        fileReader.close();



        //make sure the new file has a modified time that is different

        try

        {

            Thread.sleep(1000);

        } catch (Exception e)

        {

        }



        //clear file after reading contents

        fileWriter = new FileWriter(inputFile);

        fileWriter.write("");

        fileWriter.close();



        lastModified = inputFile.lastModified();



        setChanged();

        notifyObservers(new FileIOUpdate(IO_TYPE.READ, readerID, (long) input.length));



        return new String(input);

    }

}