package marauroa.common.io;
/*
http://koti.mbnet.fi/akini/java/unicodereader/
version: 1.1 / 2007-01-25
- changed BOM recognition ordering (longer boms first)
Original pseudocode : Thomas Weidenfeller
Implementation tweaked: Aki Nieminen
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;
/**
* 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.
*
* @since 2.1
*/
public class UnicodeSupportingInputStreamReader extends Reader {
private PushbackInputStream internalIn;
private InputStreamReader internalIn2 = null;
private String defaultEnc;
private static final int BOM_SIZE = 4;
/**
* Creates a new UnicodeSupportingInputStreamReader
*
* @param in inputstream to be read
*/
public UnicodeSupportingInputStreamReader(InputStream in) {
internalIn = new PushbackInputStream(in, BOM_SIZE);
}
/**
* Creates a new UnicodeSupportingInputStreamReader
*
* @param in inputstream to be read
* @param defaultEnc default encoding if stream does not have
* BOM marker. Give NULL to use system-level default.
*/
public UnicodeSupportingInputStreamReader(InputStream in, String defaultEnc) {
internalIn = new PushbackInputStream(in, BOM_SIZE);
this.defaultEnc = defaultEnc;
}
/**
* returns the default encoding
*
* @return default encoding
*/
public String getDefaultEncoding() {
return defaultEnc;
}
/**
* Get stream encoding or NULL if stream is uninitialized.
* Call init() or read() method to initialize it.
*
* @return actual encoding used to read this file
*/
public String getEncoding() {
if (internalIn2 == null) return null;
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 in cases of an I/O error
*/
protected void init() throws IOException {
if (internalIn2 != null) return;
String encoding;
byte bom[] = new byte[BOM_SIZE];
int n, unread;
n = internalIn.read(bom, 0, bom.length);
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 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 {
// Unicode BOM mark not found, unread all bytes
encoding = defaultEnc;
unread = n;
}
//System.out.println("read=" + n + ", unread=" + unread);
if (unread > 0) internalIn.unread(bom, (n - unread), unread);
// Use given encoding
if (encoding == null) {
internalIn2 = new InputStreamReader(internalIn);
} else {
internalIn2 = new InputStreamReader(internalIn, encoding);
}
}
@Override
public void close() throws IOException {
init();
internalIn2.close();
}
@Override
public int read(char[] cbuf, int off, int len) throws IOException {
init();
return internalIn2.read(cbuf, off, len);
}
}