info.monitorenter.cpdetector.io.ASCIIDetector Maven / Gradle / Ivy
/*
* ASCIIDetector.java, a simple implementation for cpdetector,
* that may be used to detect plain ASCII.
* Copyright (C) Achim Westermann, created on 18.10.2004, 12:56:45
*
* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this collection 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 cpDetector code in [sub] packages info.monitorenter and
* cpdetector.
*
* The Initial Developer of the Original Code is
* Achim Westermann .
*
* Portions created by the Initial Developer are Copyright (c) 2007
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
*
* 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 *****
*
* If you modify or optimize the code in a useful way please let me know.
* [email protected]
*
*/
package info.monitorenter.cpdetector.io;
import info.monitorenter.util.FileUtil;
import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.charset.Charset;
/**
*
* A simple detector that may be used to detect plain ASCII. This instance
* should never be used as the first strategy of the
* {@link info.monitorenter.cpdetector.io.CodepageDetectorProxy}: Many different encodings are
* multi-byte and may be verified to be ASCII by this instance, because all
* their bytes are in the range from 0x00 to 0x7F.
*
*
* It is recommended to use this as a fall-back, if all different strategies
* (e.g. {@link info.monitorenter.cpdetector.io.JChardetFacade},
* {@link info.monitorenter.cpdetector.io.ParsingDetector}) fail. This is most often the case for
* ASCII data, as guessing and exclusion based on the content is especially hard
* for ASCII: almost all character sets define the ASCII range (compatibility).
* Therefore this is a good fall-back.
*
*
* It is a singleton for performance-reasons: The constructor is private. Use
* {@link #getInstance()}or
* {@link info.monitorenter.cpdetector.reflect.SingletonLoader#getInstance()}
* and
* {@link info.monitorenter.cpdetector.reflect.SingletonLoader#newInstance(String)}
* on the result.
*
*
*
* @author Achim Westermann
*
*/
public final class ASCIIDetector
extends AbstractCodepageDetector {
/**
* Generated serialVersionUID.
*/
private static final long serialVersionUID = 3760841259903824181L;
private static ICodepageDetector instance;
/**
* Singleton constructor
*/
private ASCIIDetector() {
super();
// TODO Auto-generated constructor stub
}
public static ICodepageDetector getInstance() {
if (instance == null) {
instance = new ASCIIDetector();
}
return instance;
}
/**
* @see info.monitorenter.cpdetector.io.ICodepageDetector#detectCodepage(java.io.InputStream,
* int)
*/
public Charset detectCodepage(final InputStream in, final int length) throws IOException {
Charset ret = UnknownCharset.getInstance();
InputStream localin;
if (!(in instanceof BufferedInputStream)) {
localin = new BufferedInputStream(in, 4096);
} else {
localin = in;
}
if (FileUtil.isAllASCII(localin)) {
ret = Charset.forName("US-ASCII");
}
return ret;
}
}