Forcing Updates to a File to the Disk Java code example - Click here to copy ->>>

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// -----------------------------------------------------------------------------

// ForcingUpdates.java

// -----------------------------------------------------------------------------



/*

 * =============================================================================

 * Copyright (c) 1998-2005 Jeffrey M. Hunter. All rights reserved.

 * 

 * All source code and material located at the Internet address of

 * http://www.idevelopment.info is the copyright of Jeffrey M. Hunter, 2005 and

 * is protected under copyright laws of the United States. This source code may

 * not be hosted on any other site without my express, prior, written

 * permission. Application to host any of the material elsewhere can be made by

 * contacting me at jhunter@idevelopment.info.

 *

 * I have made every effort and taken great care in making sure that the source

 * code and other content included on my web site is technically accurate, but I

 * disclaim any and all responsibility for any loss, damage or destruction of



 * data or any other property which may arise from relying on it. I will in no

 * case be liable for any monetary damages arising from such loss, damage or

 * destruction.

 * 

 * As with any code, ensure to test this code in a development environment 

 * before attempting to run it in production.

 * =============================================================================

 */

 

import java.io.FileOutputStream;

import java.io.FileDescriptor;

import java.io.IOException;



/**

 * -----------------------------------------------------------------------------

 * This program demonstrates how to force updates to a file to a disk. In some

 * applications, such as transaction processing, it is necessary to ensure that

 * an update has been made to the disk. FileDescriptor.sunc() blocks until

 * all changes to a file are written to disk.

 * 

 * @version 1.0

 * @author  Jeffrey M. Hunter  (jhunter@idevelopment.info)

 * @author  http://www.idevelopment.info

 * -----------------------------------------------------------------------------

 */



public class ForcingUpdates {



    private static void doForceUpdate() {



        try {

        

            // Open or create the output file

            String           fn = "outfile.txt";

            FileOutputStream os = new FileOutputStream(fn);

            FileDescriptor   fd = os.getFD();

            System.out.println("Opened file: " + fn);



            // Write some data to the stream

            byte[] data = new byte[]{(byte)0xCA, (byte)0xFE, (byte)0xBA, (byte)0xBE};

            os.write(data);

            System.out.println("Wrote the following data to stream: " + data);



            // Flush the data from the streams and writers into system buffers.

            // The data may or may not be written to disk.

            System.out.println("Flushing from streams to system buffers.");

            os.flush();



            // Block until the system buffers have been written to disk.

            // After this method returns, the data is guaranteed to have been

            // written to disk.

            System.out.println("Blocking until system buffers have been written.");

            fd.sync();



            // Close out the file stream

            os.close();

            System.out.println("Closed file: " + fn);

        

        } catch (IOException e) {

            e.printStackTrace();

        }



    }





    /**

     * Sole entry point to the class and application.

     * @param args Array of String arguments.

     */

    public static void main(String[] args) {

        doForceUpdate();

    }



}