1 /*

     2 * Copyright (c) 2007 Nokia Corporation and/or its subsidiary(-ies). 

     3 * All rights reserved.

     4 * This component and the accompanying materials are made available

     5 * under the terms of "Eclipse Public License v1.0"

     6 * which accompanies this distribution, and is available

     7 * at the URL "http://www.eclipse.org/legal/epl-v10.html".

     8 *

     9 * Initial Contributors:

    10 * Nokia Corporation - initial contribution.

    11 *

    12 * Contributors:

    13 *

    14 * Description:

    15 *

    16 * Output stream which compares the data to existing file before writing

    17 *

    18 */

    19 package com.nokia.tracecompiler.file;

    20 

    21 import java.io.ByteArrayOutputStream;

    22 import java.io.File;

    23 import java.io.FileInputStream;

    24 import java.io.IOException;

    25 import java.io.OutputStream;

    26 

    27 /**

    28  * Output stream which writes to a byte array. When writing is complete, the

    29  * array contents are compared to existing file and the file is written only if

    30  * there are changes

    31  * 

    32  */

    33 public class FileCompareOutputStream extends ByteArrayOutputStream {

    34 

    35 	/**

    36 	 * The header file

    37 	 */

    38 	private File file;

    39 

    40 	/**

    41 	 * Creates a new stream

    42 	 * 

    43 	 * @param file

    44 	 *            the header file

    45 	 */

    46 	public FileCompareOutputStream(File file) {

    47 		this.file = file;

    48 	}

    49 

    50 	/**

    51 	 * Writes the buffer to file if it has changed

    52 	 * 

    53 	 * @return true if header was written, false if it matched the existing

    54 	 *         header

    55 	 * @throws IOException

    56 	 *             if writing fails

    57 	 */

    58 	public boolean writeFile() throws IOException {

    59 		// Compares the file length to number of bytes in array

    60 		boolean writeHeader = true;

    61 		if (file.length() == count) {

    62 			FileInputStream fis = new FileInputStream(file);

    63 			byte[] temp = new byte[count];

    64 			fis.read(temp);

    65 			fis.close();

    66 			writeHeader = false;

    67 			// Compares the file content

    68 			for (int i = 0; i < count; i++) {

    69 				if (temp[i] != buf[i]) {

    70 					writeHeader = true;

    71 					i = count;

    72 				}

    73 			}

    74 		}

    75 		if (writeHeader) {

    76 			OutputStream fos = FileUtils.createOutputStream(file);

    77 			writeTo(fos);

    78 			fos.close();

    79 		}

    80 		return writeHeader;

    81 	}

    82 }