Reads a signature if it applies. - Java java.io

Java examples for java.io:File UTF

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Description

Reads a signature if it applies.

Demo Code

/*******************************************************************************
 * Copyright (c) 2004 Actuate Corporation.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:/*from www  .  j  av a  2  s . c  om*/
 *  Actuate Corporation  - initial API and implementation
 *******************************************************************************/
//package com.java2s;
import java.io.IOException;
import java.io.InputStream;

public class Main {
    /**
     * The signature for the UTF-8 files.
     */

    public final static String SIGNATURE_UTF_8 = "UTF-8";
    /**
     * The signature for the Unicode Big Endian files.
     */

    public final static String SIGNATURE_UNICODE_BIG = "UnicodeBig";
    /**
     * The signature for the Unicode Little Endian files.
     */

    public final static String SIGNATURE_UNICODE_LITTLE = "UnicodeLittle";
    /**
     * The signature for the UCS4 Big Endian files.
     */

    public final static String SIGNATURE_UCS4_BIG = "UCS-4Big";
    /**
     * The signature for the UCS4 Little Endian files.
     */

    public final static String SIGNATURE_UCS4_LITTLE = "UCS-4Little";

    /**
     * Reads a signature if it applies. Currently BIRT can recognize the
     * following signatures:
     * 
     * <ul>
     * <li>SIGNATURE_UTF_8</li>
     * <li>SIGNATURE_UNICODE_BIG</li>
     * <li>SIGNATURE_UNICODE_LITTLE</li>
     * <li>SIGNATURE_UCS4_BIG_8</li>
     * <li>SIGNATURE_UCS4_LITTLE</li>
     * </ul>
     * 
     * @param inputStream
     *            the input stream of the unicode file
     * 
     * @return the encoding signature from the unicode file.
     * 
     * @throws IOException
     *             if errors occur when reading bytes from the input stream
     */

    public static String checkUTFSignature(InputStream inputStream)
            throws IOException {

        inputStream.mark(1024);

        int byte1 = inputStream.read();
        int byte2 = inputStream.read();
        if (byte1 == 0xFE && byte2 == 0xFF) {
            return SIGNATURE_UNICODE_BIG;
        } else if (byte1 == 0xFF && byte2 == 0xFE) {

            return SIGNATURE_UNICODE_LITTLE;
        }

        int byte3 = inputStream.read();

        // check for UTF-8 byte order mark

        if (byte1 == 0xEF && byte2 == 0xBB && byte3 == 0xBF) {
            return SIGNATURE_UTF_8;
        }

        int byte4 = inputStream.read();
        if (byte1 == 0x00 && byte2 == 0x00 && byte3 == 0xFE
                && byte4 == 0xFF) {
            return SIGNATURE_UCS4_BIG;
        } else if (byte1 == 0x00 && byte2 == 0x00 && byte3 == 0xFF
                && byte4 == 0xFE) {
            return SIGNATURE_UCS4_LITTLE;
        }

        inputStream.reset();
        return null;
    }
}

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