Java InputStream Read by Charset getHeaderLen(FileInputStream in, Charset encoding)

Here you can find the source of getHeaderLen(FileInputStream in, Charset encoding)

Description

get Header Len

License

LGPL

Declaration

private static long getHeaderLen(FileInputStream in, Charset encoding) throws IOException 

Method Source Code

//package com.java2s;
/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1//  w w w  . j  a va 2 s . c om
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is the FRIL Framework.
 *
 * The Initial Developers of the Original Code are
 * The Department of Math and Computer Science, Emory University and 
 * The Centers for Disease Control and Prevention.
 * Portions created by the Initial Developer are Copyright (C) 2008
 * the Initial Developer. All Rights Reserved.
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

import java.io.FileInputStream;

import java.io.IOException;
import java.io.InputStream;

import java.nio.charset.Charset;

public class Main {
    private static long getHeaderLen(FileInputStream in, Charset encoding) throws IOException {
        byte[] expectedHeader = getHeader(encoding);
        byte[] magic = new byte[expectedHeader.length];
        int read = readGuaranteed(magic, in);
        if (read != expectedHeader.length) {
            return 0;
        }
        for (int i = 0; i < magic.length; i++) {
            if (magic[i] != expectedHeader[i]) {
                return 0;
            }
        }
        return magic.length;
    }

    private static byte[] getHeader(Charset encoding) {
        byte[] header = null;
        if (encoding.toString().equals("UTF-32LE")) {
            header = new byte[] { (byte) 0xFF, (byte) 0xFE, (byte) 0x00, (byte) 0x00 };
        } else if (encoding.toString().equals("UTF-32BE")) {
            header = new byte[] { (byte) 0x00, (byte) 0x00, (byte) 0xFE, (byte) 0xFF };
        } else if (encoding.toString().equals("UTF-16LE")) {
            header = new byte[] { (byte) 0xFF, (byte) 0xFE };
        } else if (encoding.toString().equals("UTF-16BE")) {
            header = new byte[] { (byte) 0xFE, (byte) 0xFF };
        } else if (encoding.toString().equals("UTF-8")) {
            header = new byte[] { (byte) 0xEF, (byte) 0xBB, (byte) 0xBF };
        } else {
            header = new byte[] {};
        }
        return header;
    }

    private static int readGuaranteed(byte[] magic, InputStream str) throws IOException {
        int read = 0;
        int tmp = 0;
        while ((tmp = str.read(magic, read, magic.length - read)) != -1) {
            read += tmp;
            if (read == magic.length) {
                break;
            }
        }
        return read;
    }
}

Related

  1. createInput(String s, String charsetName)
  2. createZipInputStream(InputStream inStream, Charset charset)
  3. forceEncoding(String inputString, String targetCharset)
  4. fromUnicode(String charset, String input)
  5. getContentFromInputStream(InputStream in, String charset)
  6. getInputCharset()
  7. getStreamAsString(InputStream source, Charset charset)
  8. getText(InputStream stream, Charset charset)
  9. input2String(InputStream input, Charset encoding)