/*
* 09/24/2004
*
* UnicodeWriter.java - Writes Unicode output with the proper BOM.
*
* This library is distributed under a modified BSD license. See the included
* RSyntaxTextArea.License.txt file for details.
*/
package org.fife.io;
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 preceded by the proper Unicode BOM. If it is any
* other encoding, this class behaves just like <code>OutputStreamWriter</code>.
* This class is here because Java's <code>OutputStreamWriter</code> apparently
* doesn't believe in writing BOMs.
* <p>
*
* For optimum performance, it is recommended that you wrap all instances of
* <code>UnicodeWriter</code> with a <code>java.io.BufferedWriter</code>.
*
* @author Robert Futrell
* @version 0.7
*/
public class UnicodeWriter extends Writer {
/**
* If this system property evaluates to "<code>false</code>", 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 UnicodeWriter(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 UnicodeWriter(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 UnicodeWriter(OutputStream out, String encoding)
throws UnsupportedEncodingException, IOException {
init(out, encoding);
}
/**
* Closes this writer.
*
* @throws IOException If an IO exception occurs.
*/
@Override
public void close() throws IOException {
internalOut.close();
}
/**
* Flushes the stream.
*
* @throws IOException If an IO exception occurs.
*/
@Override
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();
}
/**
* Returns whether UTF-8 files should have a BOM in them when written.
*
* @return Whether to write a BOM for UTF-8 files.
*/
public static boolean getWriteUtf8BOM() {
String prop = System.getProperty(PROPERTY_WRITE_UTF8_BOM);
if (prop!=null && Boolean.valueOf(prop).equals(Boolean.FALSE)) {
return false;
}
return true;
}
/**
* 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
// DOES write out the BOM; "UTF-16LE", "UTF-16BE", "UTF-32", "UTF-32LE"
// and "UTF-32BE" don't.
if ("UTF-8".equals(encoding)) {
if (getWriteUtf8BOM()) {
out.write(UTF8_BOM, 0, UTF8_BOM.length);
}
}
else if ("UTF-16LE".equals(encoding)) {
out.write(UTF16LE_BOM, 0, UTF16LE_BOM.length);
}
else if (/*"UTF-16".equals(encoding) || */"UTF-16BE".equals(encoding)) {
out.write(UTF16BE_BOM, 0, UTF16BE_BOM.length);
}
else if ("UTF-32LE".equals(encoding)) {
out.write(UTF32LE_BOM, 0, UTF32LE_BOM.length);
}
else if ("UTF-32".equals(encoding) || "UTF-32BE".equals(encoding)) {
out.write(UTF32BE_BOM, 0, UTF32BE_BOM.length);
}
}
/**
* 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.
*/
@Override
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.
*/
@Override
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.
*/
@Override
public void write(String str, int off, int len) throws IOException {
internalOut.write(str, off, len);
}
}