javolution.io.UTF8StreamWriter Maven / Gradle / Ivy
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/*
* Javolution - Java(TM) Solution for Real-Time and Embedded Systems
* Copyright (C) 2012 - Javolution (http://javolution.org/)
* All rights reserved.
*
* Permission to use, copy, modify, and distribute this software is
* freely granted, provided that this notice is preserved.
*/
package javolution.io;
import java.io.CharConversionException;
import java.io.IOException;
import java.io.OutputStream;
import java.io.Writer;
/**
* A UTF-8 stream writer.
*
* This writer supports surrogate char pairs (representing
* characters in the range [U+10000 .. U+10FFFF]). It can also be used
* to write characters from their unicodes (31 bits) directly
* (ref. {@link #write(int)}).
*
* Instances of this class can be reused for different output streams
* and can be part of a higher level component (e.g. serializer) in order
* to avoid dynamic buffer allocation when the destination output changes.
* Also wrapping using a java.io.BufferedWriter is unnescessary
* as instances of this class embed their own data buffers.
*
* Note: This writer is unsynchronized and always produces well-formed
* UTF-8 sequences.
*
* @author Jean-Marie Dautelle
* @version 2.0, December 9, 2004
*/
public final class UTF8StreamWriter extends Writer {
/**
* Holds the current output stream or null if closed.
*/
private OutputStream _outputStream;
/**
* Holds the bytes' buffer.
*/
private final byte[] _bytes;
/**
* Holds the bytes buffer index.
*/
private int _index;
/**
* Creates a UTF-8 writer having a byte buffer of moderate capacity (2048).
*/
public UTF8StreamWriter() {
_bytes = new byte[2048];
}
/**
* Creates a UTF-8 writer having a byte buffer of specified capacity.
*
* @param capacity the capacity of the byte buffer.
*/
public UTF8StreamWriter(int capacity) {
_bytes = new byte[capacity];
}
/**
* Sets the output stream to use for writing until this writer is closed.
* For example:[code]
* Writer writer = new UTF8StreamWriter().setOutputStream(out);
* [/code] is equivalent but writes faster than [code]
* Writer writer = new java.io.OutputStreamWriter(out, "UTF-8");
* [/code]
*
* @param out the output stream.
* @return this UTF-8 writer.
* @throws IllegalStateException if this writer is being reused and
* it has not been {@link #close closed} or {@link #reset reset}.
*/
public UTF8StreamWriter setOutput(OutputStream out) {
if (_outputStream != null)
throw new IllegalStateException("Writer not closed or reset");
_outputStream = out;
return this;
}
/**
* Writes a single character. This method supports 16-bits
* character surrogates.
*
* @param c char the character to be written (possibly
* a surrogate).
* @throws IOException if an I/O error occurs.
*/
public void write(char c) throws IOException {
if ((c < 0xd800) || (c > 0xdfff)) {
write((int) c);
} else if (c < 0xdc00) { // High surrogate.
_highSurrogate = c;
} else { // Low surrogate.
int code = ((_highSurrogate - 0xd800) << 10) + (c - 0xdc00)
+ 0x10000;
write(code);
}
}
private char _highSurrogate;
/**
* Writes a character given its 31-bits Unicode.
*
* @param code the 31 bits Unicode of the character to be written.
* @throws IOException if an I/O error occurs.
*/
public void write(int code) throws IOException {
if ((code & 0xffffff80) == 0) {
_bytes[_index] = (byte) code;
if (++_index >= _bytes.length) {
flushBuffer();
}
} else { // Writes more than one byte.
write2(code);
}
}
private void write2(int c) throws IOException {
if ((c & 0xfffff800) == 0) { // 2 bytes.
_bytes[_index] = (byte) (0xc0 | (c >> 6));
if (++_index >= _bytes.length) {
flushBuffer();
}
_bytes[_index] = (byte) (0x80 | (c & 0x3f));
if (++_index >= _bytes.length) {
flushBuffer();
}
} else if ((c & 0xffff0000) == 0) { // 3 bytes.
_bytes[_index] = (byte) (0xe0 | (c >> 12));
if (++_index >= _bytes.length) {
flushBuffer();
}
_bytes[_index] = (byte) (0x80 | ((c >> 6) & 0x3f));
if (++_index >= _bytes.length) {
flushBuffer();
}
_bytes[_index] = (byte) (0x80 | (c & 0x3f));
if (++_index >= _bytes.length) {
flushBuffer();
}
} else if ((c & 0xff200000) == 0) { // 4 bytes.
_bytes[_index] = (byte) (0xf0 | (c >> 18));
if (++_index >= _bytes.length) {
flushBuffer();
}
_bytes[_index] = (byte) (0x80 | ((c >> 12) & 0x3f));
if (++_index >= _bytes.length) {
flushBuffer();
}
_bytes[_index] = (byte) (0x80 | ((c >> 6) & 0x3f));
if (++_index >= _bytes.length) {
flushBuffer();
}
_bytes[_index] = (byte) (0x80 | (c & 0x3f));
if (++_index >= _bytes.length) {
flushBuffer();
}
} else if ((c & 0xf4000000) == 0) { // 5 bytes.
_bytes[_index] = (byte) (0xf8 | (c >> 24));
if (++_index >= _bytes.length) {
flushBuffer();
}
_bytes[_index] = (byte) (0x80 | ((c >> 18) & 0x3f));
if (++_index >= _bytes.length) {
flushBuffer();
}
_bytes[_index] = (byte) (0x80 | ((c >> 12) & 0x3f));
if (++_index >= _bytes.length) {
flushBuffer();
}
_bytes[_index] = (byte) (0x80 | ((c >> 6) & 0x3f));
if (++_index >= _bytes.length) {
flushBuffer();
}
_bytes[_index] = (byte) (0x80 | (c & 0x3f));
if (++_index >= _bytes.length) {
flushBuffer();
}
} else if ((c & 0x80000000) == 0) { // 6 bytes.
_bytes[_index] = (byte) (0xfc | (c >> 30));
if (++_index >= _bytes.length) {
flushBuffer();
}
_bytes[_index] = (byte) (0x80 | ((c >> 24) & 0x3f));
if (++_index >= _bytes.length) {
flushBuffer();
}
_bytes[_index] = (byte) (0x80 | ((c >> 18) & 0x3f));
if (++_index >= _bytes.length) {
flushBuffer();
}
_bytes[_index] = (byte) (0x80 | ((c >> 12) & 0x3F));
if (++_index >= _bytes.length) {
flushBuffer();
}
_bytes[_index] = (byte) (0x80 | ((c >> 6) & 0x3F));
if (++_index >= _bytes.length) {
flushBuffer();
}
_bytes[_index] = (byte) (0x80 | (c & 0x3F));
if (++_index >= _bytes.length) {
flushBuffer();
}
} else {
throw new CharConversionException("Illegal character U+"
+ Integer.toHexString(c));
}
}
/**
* Writes a portion of an array of characters.
*
* @param cbuf the array 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 {
final int off_plus_len = off + len;
for (int i = off; i < off_plus_len;) {
char c = cbuf[i++];
if (c < 0x80) {
_bytes[_index] = (byte) c;
if (++_index >= _bytes.length) {
flushBuffer();
}
} else {
write(c);
}
}
}
/**
* Writes a portion of a string.
*
* @param str a String.
* @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(String str, int off, int len) throws IOException {
final int off_plus_len = off + len;
for (int i = off; i < off_plus_len;) {
char c = str.charAt(i++);
if (c < 0x80) {
_bytes[_index] = (byte) c;
if (++_index >= _bytes.length) {
flushBuffer();
}
} else {
write(c);
}
}
}
/**
* Writes the specified character sequence.
*
* @param csq the character sequence.
* @throws IOException if an I/O error occurs
*/
public void write(CharSequence csq) throws IOException {
final int length = csq.length();
for (int i = 0; i < length;) {
char c = csq.charAt(i++);
if (c < 0x80) {
_bytes[_index] = (byte) c;
if (++_index >= _bytes.length) {
flushBuffer();
}
} else {
write(c);
}
}
}
/**
* Flushes the stream. If the stream has saved any characters from the
* various write() methods in a buffer, write them immediately to their
* intended destination. Then, if that destination is another character or
* byte stream, flush it. Thus one flush() invocation will flush all the
* buffers in a chain of Writers and OutputStreams.
*
* @throws IOException if an I/O error occurs.
*/
public void flush() throws IOException {
flushBuffer();
_outputStream.flush();
}
/**
* Closes and {@link #reset resets} this writer for reuse.
*
* @throws IOException if an I/O error occurs
*/
public void close() throws IOException {
if (_outputStream != null) {
flushBuffer();
_outputStream.close();
reset();
}
}
/**
* Flushes the internal bytes buffer.
*
* @throws IOException if an I/O error occurs
*/
private void flushBuffer() throws IOException {
if (_outputStream == null)
throw new IOException("Stream closed");
_outputStream.write(_bytes, 0, _index);
_index = 0;
}
public void reset() {
_highSurrogate = 0;
_index = 0;
_outputStream = null;
}
/**
* @deprecated Replaced by {@link #setOutput(OutputStream)}
*/
public UTF8StreamWriter setOutputStream(OutputStream out) {
return this.setOutput(out);
}
}