Each invocation of a write() method causes the encoding converter to be * invoked on the given character(s). The resulting bytes are accumulated in a * buffer before being written to the underlying output stream. The size of * this buffer may be specified, but by default it is large enough for most * purposes. Note that the characters passed to the write() methods are not * buffered. * *
For top efficiency, consider wrapping an OutputStreamWriter within a * BufferedWriter so as to avoid frequent converter invocations. For example: * *
* Writer out * = new BufferedWriter(new OutputStreamWriter(System.out)); ** *
A surrogate pair is a character represented by a sequence of two * {@code char} values: A high surrogate in the range '\uD800' to * '\uDBFF' followed by a low surrogate in the range '\uDC00' to * '\uDFFF'. * *
A malformed surrogate element is a high surrogate that is not * followed by a low surrogate or a low surrogate that is not preceded by a * high surrogate. * *
This class always replaces malformed surrogate elements and unmappable * character sequences with the charset's default substitution sequence. * The {@linkplain java.nio.charset.CharsetEncoder} class should be used when more * control over the encoding process is required. * * @see BufferedWriter * @see OutputStream * @see java.nio.charset.Charset * * @author Mark Reinhold * @since 1.1 */ public class OutputStreamWriter extends Writer { private final StreamEncoder se; /** * Creates an OutputStreamWriter that uses the named charset. * * @param out * An OutputStream * * @param charsetName * The name of a supported * {@link java.nio.charset.Charset charset} * * @exception UnsupportedEncodingException * If the named encoding is not supported */ public OutputStreamWriter(OutputStream out, String charsetName) throws UnsupportedEncodingException { super(out); if (charsetName == null) throw new NullPointerException("charsetName"); se = StreamEncoder.forOutputStreamWriter(out, this, charsetName); } /** * Creates an OutputStreamWriter that uses the default character encoding. * * @param out An OutputStream */ public OutputStreamWriter(OutputStream out) { super(out); try { se = StreamEncoder.forOutputStreamWriter(out, this, (String)null); } catch (UnsupportedEncodingException e) { throw new Error(e); } } /** * Creates an OutputStreamWriter that uses the given charset. * * @param out * An OutputStream * * @param cs * A charset * * @since 1.4 * @spec JSR-51 */ public OutputStreamWriter(OutputStream out, Charset cs) { super(out); if (cs == null) throw new NullPointerException("charset"); se = StreamEncoder.forOutputStreamWriter(out, this, cs); } /** * Creates an OutputStreamWriter that uses the given charset encoder. * * @param out * An OutputStream * * @param enc * A charset encoder * * @since 1.4 * @spec JSR-51 */ public OutputStreamWriter(OutputStream out, CharsetEncoder enc) { super(out); if (enc == null) throw new NullPointerException("charset encoder"); se = StreamEncoder.forOutputStreamWriter(out, this, enc); } /** * Returns the name of the character encoding being used by this stream. * *
If the encoding has an historical name then that name is returned; * otherwise the encoding's canonical name is returned. * *
If this instance was created with the {@link * #OutputStreamWriter(OutputStream, String)} constructor then the returned * name, being unique for the encoding, may differ from the name passed to * the constructor. This method may return {@code null} if the stream has * been closed.
* * @return The historical name of this encoding, or possibly *null if the stream has been closed
*
* @see java.nio.charset.Charset
*
* @revised 1.4
* @spec JSR-51
*/
public String getEncoding() {
return se.getEncoding();
}
/**
* Flushes the output buffer to the underlying byte stream, without flushing
* the byte stream itself. This method is non-private only so that it may
* be invoked by PrintStream.
*/
void flushBuffer() throws IOException {
se.flushBuffer();
}
/**
* Writes a single character.
*
* @exception IOException If an I/O error occurs
*/
public void write(int c) throws IOException {
se.write(c);
}
/**
* Writes a portion of an array of characters.
*
* @param cbuf Buffer of characters
* @param off Offset from which to start writing characters
* @param len Number of characters to write
*
* @throws IndexOutOfBoundsException
* If {@code off} is negative, or {@code len} is negative,
* or {@code off + len} is negative or greater than the length
* of the given array
*
* @throws IOException If an I/O error occurs
*/
public void write(char cbuf[], int off, int len) throws IOException {
se.write(cbuf, off, len);
}
/**
* Writes a portion of a string.
*
* @param str A String
* @param off Offset from which to start writing characters
* @param len Number of characters to write
*
* @throws IndexOutOfBoundsException
* If {@code off} is negative, or {@code len} is negative,
* or {@code off + len} is negative or greater than the length
* of the given string
*
* @throws IOException If an I/O error occurs
*/
public void write(String str, int off, int len) throws IOException {
se.write(str, off, len);
}
@Override
public Writer append(CharSequence csq, int start, int end) throws IOException {
if (csq == null) csq = "null";
return append(csq.subSequence(start, end));
}
@Override
public Writer append(CharSequence csq) throws IOException {
if (csq instanceof CharBuffer) {
se.write((CharBuffer) csq);
} else {
se.write(String.valueOf(csq));
}
return this;
}
/**
* Flushes the stream.
*
* @exception IOException If an I/O error occurs
*/
public void flush() throws IOException {
se.flush();
}
public void close() throws IOException {
se.close();
}
}