org.yaml.snakeyaml.reader.UnicodeReader Maven / Gradle / Ivy
/**
* Copyright (c) 2008, http://www.snakeyaml.org
*
* Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.yaml.snakeyaml.reader;
/**
version: 1.1 / 2007-01-25
- changed BOM recognition ordering (longer boms first)
Original pseudocode : Thomas Weidenfeller
Implementation tweaked: Aki Nieminen
Implementation changed: Andrey Somov
* UTF-32 removed because it is not supported by YAML
* no default encoding
http://www.unicode.org/unicode/faq/utf_bom.html
BOMs:
00 00 FE FF = UTF-32, big-endian
FF FE 00 00 = UTF-32, little-endian
EF BB BF = UTF-8,
FE FF = UTF-16, big-endian
FF FE = UTF-16, little-endian
Win2k Notepad:
Unicode format = UTF-16LE
***/
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PushbackInputStream;
import java.io.Reader;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import java.nio.charset.CodingErrorAction;
/**
* Generic unicode textreader, which will use BOM mark to identify the encoding
* to be used. If BOM is not found then use a given default or system encoding.
*/
public class UnicodeReader extends Reader {
private static final Charset UTF8 = Charset.forName("UTF-8");
private static final Charset UTF16BE = Charset.forName("UTF-16BE");
private static final Charset UTF16LE = Charset.forName("UTF-16LE");
PushbackInputStream internalIn;
InputStreamReader internalIn2 = null;
private static final int BOM_SIZE = 3;
/**
* @param in
* InputStream to be read
*/
public UnicodeReader(InputStream in) {
internalIn = new PushbackInputStream(in, BOM_SIZE);
}
/**
* Get stream encoding or NULL if stream is uninitialized. Call init() or
* read() method to initialize it.
* @return the name of the character encoding being used by this stream.
*/
public String getEncoding() {
return internalIn2.getEncoding();
}
/**
* Read-ahead four bytes and check for BOM marks. Extra bytes are unread
* back to the stream, only BOM bytes are skipped.
* @throws IOException if InputStream cannot be created
*/
protected void init() throws IOException {
if (internalIn2 != null)
return;
Charset encoding;
byte bom[] = new byte[BOM_SIZE];
int n, unread;
n = internalIn.read(bom, 0, bom.length);
if ((bom[0] == (byte) 0xEF) && (bom[1] == (byte) 0xBB) && (bom[2] == (byte) 0xBF)) {
encoding = UTF8;
unread = n - 3;
} else if ((bom[0] == (byte) 0xFE) && (bom[1] == (byte) 0xFF)) {
encoding = UTF16BE;
unread = n - 2;
} else if ((bom[0] == (byte) 0xFF) && (bom[1] == (byte) 0xFE)) {
encoding = UTF16LE;
unread = n - 2;
} else {
// Unicode BOM mark not found, unread all bytes
encoding = UTF8;
unread = n;
}
if (unread > 0)
internalIn.unread(bom, (n - unread), unread);
// Use given encoding
CharsetDecoder decoder = encoding.newDecoder().onUnmappableCharacter(
CodingErrorAction.REPORT);
internalIn2 = new InputStreamReader(internalIn, decoder);
}
public void close() throws IOException {
init();
internalIn2.close();
}
public int read(char[] cbuf, int off, int len) throws IOException {
init();
return internalIn2.read(cbuf, off, len);
}
}