com.exactpro.sf.util.UnicodeReader Maven / Gradle / Ivy
/******************************************************************************
* Copyright 2009-2018 Exactpro (Exactpro Systems Limited)
*
* 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 com.exactpro.sf.util;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PushbackInputStream;
import java.io.Reader;
public class UnicodeReader extends Reader {
private static final int BOM_SIZE = 4;
private final InputStreamReader reader;
/**
* Construct UnicodeReader
* @param in Input stream.
* @param defaultEncoding Default encoding to be used if BOM is not found,
* or null to use system default encoding.
* @throws IOException If an I/O error occurs.
*/
public UnicodeReader(InputStream in, String defaultEncoding) throws IOException {
byte[] bom = new byte[BOM_SIZE];
String encoding;
int unread;
PushbackInputStream pushbackStream = new PushbackInputStream(in, BOM_SIZE);
int n = pushbackStream.read(bom, 0, bom.length);
// Read ahead four bytes and check for BOM marks.
if ((bom[0] == (byte) 0xEF) && (bom[1] == (byte) 0xBB) && (bom[2] == (byte) 0xBF)) {
encoding = "UTF-8";
unread = n - 3;
} else if ((bom[0] == (byte) 0xFE) && (bom[1] == (byte) 0xFF)) {
encoding = "UTF-16BE";
unread = n - 2;
} else if ((bom[0] == (byte) 0xFF) && (bom[1] == (byte) 0xFE)) {
encoding = "UTF-16LE";
unread = n - 2;
} else if ((bom[0] == (byte) 0x00) && (bom[1] == (byte) 0x00) && (bom[2] == (byte) 0xFE) && (bom[3] == (byte) 0xFF)) {
encoding = "UTF-32BE";
unread = n - 4;
} else if ((bom[0] == (byte) 0xFF) && (bom[1] == (byte) 0xFE) && (bom[2] == (byte) 0x00) && (bom[3] == (byte) 0x00)) {
encoding = "UTF-32LE";
unread = n - 4;
} else {
encoding = defaultEncoding;
unread = n;
}
// Unread bytes if necessary and skip BOM marks.
if (unread > 0) {
pushbackStream.unread(bom, n - unread, unread);
} else if (unread < -1) {
pushbackStream.unread(bom, 0, 0);
}
// Use given encoding.
reader = encoding == null ? new InputStreamReader(pushbackStream) : new InputStreamReader(pushbackStream, encoding);
}
public String getEncoding() {
return reader.getEncoding();
}
@Override
public int read(char[] cbuf, int off, int len) throws IOException {
return reader.read(cbuf, off, len);
}
@Override
public void close() throws IOException {
reader.close();
}
}