net.sf.okapi.common.UnicodeBOMWriter Maven / Gradle / Ivy
/*
* 09/24/2004
*
* UnicodeWriter.java - Writes Unicode output with the proper BOM.
* Copyright (C) 2004 Robert Futrell
* robert_futrell at users.sourceforge.net
* http://fifesoft.com/rsyntaxtextarea
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
*/
package net.sf.okapi.common;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
import java.io.Writer;
/**
* Writes Unicode text to an output stream. If the specified encoding is a
* Unicode, then the text is preceeded by the proper Unicode BOM. If it is any
* other encoding, this class behaves just like OutputStreamWriter.
* This class is here because Java's OutputStreamWriter apparently
* doesn't believe in writing BOMs.
*
*
* For optimum performance, it is recommended that you wrap all instances of
* UnicodeWriter with a java.io.BufferedWriter.
*
* @author Robert Futrell
* @version 0.7
*/
public class UnicodeBOMWriter extends Writer {
/**
* If this system property evaluates to "false", ignoring
* case, files written out as UTF-8 will not have a BOM written for them.
* Otherwise (even if the property is not set), UTF-8 files will have a
* BOM written.
*/
public static final String PROPERTY_WRITE_UTF8_BOM =
"UnicodeWriter.writeUtf8BOM";
/**
* The writer actually doing the writing.
*/
private OutputStreamWriter internalOut;
private static final byte[] UTF8_BOM = new byte[] {
(byte)0xEF,
(byte)0xBB,
(byte)0xBF
};
private static final byte[] UTF16LE_BOM = new byte[] {
(byte)0xFF,
(byte)0xFE
};
private static final byte[] UTF16BE_BOM = new byte[] {
(byte)0xFE,
(byte)0xFF
};
private static final byte[] UTF32LE_BOM = new byte[] {
(byte)0xFF,
(byte)0xFE,
(byte)0x00,
(byte)0x00
};
private static final byte[] UTF32BE_BOM = new byte[] {
(byte)0x00,
(byte)0x00,
(byte)0xFE,
(byte)0xFF
};
/**
* This is a utility constructor since the vast majority of the time, this
* class will be used to write Unicode files.
*
* @param fileName The file to which to write the Unicode output.
* @param encoding The encoding to use.
* @throws UnsupportedEncodingException If the specified encoding is not
* supported.
* @throws IOException If an IO exception occurs.
*/
public UnicodeBOMWriter(String fileName, String encoding)
throws UnsupportedEncodingException, IOException {
this(new FileOutputStream(fileName), encoding);
}
/**
* This is a utility constructor since the vast majority of the time, this
* class will be used to write Unicode files.
*
* @param file The file to which to write the Unicode output.
* @param encoding The encoding to use.
* @throws UnsupportedEncodingException If the specified encoding is not
* supported.
* @throws IOException If an IO exception occurs.
*/
public UnicodeBOMWriter(File file, String encoding)
throws UnsupportedEncodingException, IOException {
this(new FileOutputStream(file), encoding);
}
/**
* Creates a new writer.
*
* @param out The output stream to write.
* @param encoding The encoding to use.
* @throws UnsupportedEncodingException If the specified encoding is not
* supported.
* @throws IOException If an IO exception occurs.
*/
public UnicodeBOMWriter(OutputStream out, String encoding)
throws UnsupportedEncodingException, IOException {
init(out, encoding);
}
/**
* Closes this writer.
*
* @throws IOException If an IO exception occurs.
*/
public void close() throws IOException {
internalOut.close();
}
/**
* Flushes the stream.
*
* @throws IOException If an IO exception occurs.
*/
public void flush() throws IOException {
internalOut.flush();
}
/**
* Returns the encoding being used to write this output stream (i.e., the
* encoding of the file).
*
* @return The encoding of the stream.
*/
public String getEncoding() {
return internalOut.getEncoding();
}
/**
* Initializes the internal output stream and writes the BOM if the
* specified encoding is a Unicode encoding.
*
* @param out The output stream we are writing.
* @param encoding The encoding in which to write.
* @throws UnsupportedEncodingException If the specified encoding isn't
* supported.
* @throws IOException If an I/O error occurs while writing a BOM.
*/
private void init(OutputStream out, String encoding)
throws UnsupportedEncodingException, IOException {
internalOut = new OutputStreamWriter(out, encoding);
// Write the proper BOM if they specified a Unicode encoding.
// NOTE: Creating an OutputStreamWriter with encoding "UTF-16"
// DOES write out the BOM; "UTF-16LE", "UTF-16BE", "UTF-32", "UTF-32LE"
// and "UTF-32BE" don't.
switch (encoding) {
case "UTF-8":
if (writeUtf8BOM()) {
out.write(UTF8_BOM, 0, UTF8_BOM.length);
}
break;
case "UTF-16LE":
out.write(UTF16LE_BOM, 0, UTF16LE_BOM.length);
break;
case "UTF-16BE":
/*"UTF-16".equals(encoding) || */
out.write(UTF16BE_BOM, 0, UTF16BE_BOM.length);
break;
case "UTF-32LE":
out.write(UTF32LE_BOM, 0, UTF32LE_BOM.length);
break;
case "UTF-32":
case "UTF-32BE":
out.write(UTF32BE_BOM, 0, UTF32BE_BOM.length);
break;
}
}
/**
* Writes a portion of an array of characters.
*
* @param cbuf The buffer of characters.
* @param off The offset from which to start writing characters.
* @param len The number of characters to write.
* @throws IOException If an I/O error occurs.
*/
public void write(char[] cbuf, int off, int len) throws IOException {
internalOut.write(cbuf, off, len);
}
/**
* Writes a single character.
*
* @param c An integer specifying the character to write.
* @throws IOException If an IO error occurs.
*/
public void write(int c) throws IOException {
internalOut.write(c);
}
/**
* Writes a portion of a string.
*
* @param str The string from which to write.
* @param off The offset from which to start writing characters.
* @param len The number of characters to write.
* @throws IOException If an IO error occurs.
*/
public void write(String str, int off, int len) throws IOException {
internalOut.write(str, off, len);
}
/**
* Returns whether UTF-8 files should have a BOM in them when written.
*
* @return Whether to write a BOM for UTF-8 files.
*/
private boolean writeUtf8BOM() {
String prop = System.getProperty(PROPERTY_WRITE_UTF8_BOM);
if (prop!=null && Boolean.valueOf(prop).equals(Boolean.FALSE)) {
return false;
}
return true;
}
}