js.io

Class WriterOutputStream

java.lang.Object

java.io.OutputStream

js.io.WriterOutputStream

All Implemented Interfaces:

Closeable, Flushable, AutoCloseable

public class WriterOutputStream
extends OutputStream

Convert characters writer to output bytes stream using UTF-8 encoding. While operates on output stream, bytes are written to input buffer then processBytesBuffer(boolean) is invoked. This takes care to decode bytes into characters using UTF-8 decoder and write them to output buffer. On output stream explicit flush or close or on input buffer overflow, output buffer is transfered to underlying target writer.

Version:

final

Author:

Iulian Rotaru

Field Summary

Fields

Modifier and Type	Field and Description
private static int	BYTES_BUFFER_SIZE Size of internal bytes buffer.
private ByteBuffer	bytesBuffer Bytes buffer used as input for the decoder.
private static int	CHARACTERS_BUFFER_SIZE Size of internal characters buffer.
private CharBuffer	charactersBuffer Characters buffer used as output for the decoder.
private CharsetDecoder	decoder Decode characters from UTF-8 bytes.
private Writer	writer Target writer.

Constructor Summary

Constructors

Constructor and Description
WriterOutputStream(Writer writer) Constructs output stream for target writer, using UTF-8 decoder.

Method Summary

Modifier and Type	Method and Description
void	close() Close output stream.
void	flush() Flush output stream.
private void	flushCharactersBuffer() Flush characters buffer to underlying writer.
private void	processBytesBuffer(boolean endOfInput) Decode the contents of input bytes buffer into the characters buffer.
void	write(byte[] b) Write bytes from the specified byte array to the stream.
void	write(byte[] b, int off, int len) Write bytes from the specified byte array to the stream.
void	write(int b) Write a single byte to the stream.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

BYTES_BUFFER_SIZE

private static final int BYTES_BUFFER_SIZE

Size of internal bytes buffer. See bytesBuffer.

See Also:

Constant Field Values

CHARACTERS_BUFFER_SIZE

private static final int CHARACTERS_BUFFER_SIZE

Size of internal characters buffer. See charactersBuffer.

See Also:

Constant Field Values

decoder

private final CharsetDecoder decoder

Decode characters from UTF-8 bytes. Charset decoder transforms a sequence of UTF-8 bytes into a sequence of 16-bit Unicode characters. Basically decoder reads from bytesBuffer and writes characters to charactersBuffer.

bytesBuffer

private final ByteBuffer bytesBuffer

Bytes buffer used as input for the decoder. All output stream write operations fill in this bytes buffer.

charactersBuffer

private final CharBuffer charactersBuffer

Characters buffer used as output for the decoder. Stores decoded characters before writing to underlying target writer. This output buffer will only be flushed when it overflows or when flush() or close() is called.

writer

private final Writer writer

Target writer.

Constructor Detail

WriterOutputStream

public WriterOutputStream(Writer writer)

Constructs output stream for target writer, using UTF-8 decoder.

Parameters:

writer - target writer.

Method Detail

write

public void write(byte[] b,
                  int off,
                  int len)
           throws IOException

Write bytes from the specified byte array to the stream.

Overrides:

write in class OutputStream

Parameters:

b - the byte array containing the bytes to write,

off - the start offset in the byte array,

len - the number of bytes to write.

Throws:

IOException - if writing operation to underlying target writer fails.

write

public void write(byte[] b)
           throws IOException

Write bytes from the specified byte array to the stream. This method just delegates write(byte[], int, int) using entire buffer.

Overrides:

write in class OutputStream

Parameters:

b - the byte array containing the bytes to write.

Throws:

IOException - if writing operation to underlying target writer fails.

write

public void write(int b)
           throws IOException

Write a single byte to the stream. If bytes buffer is full invokes processBytesBuffer(boolean) first.

Specified by:

write in class OutputStream

Parameters:

b - the byte to write.

Throws:

IOException - if writing operation to underlying target writer fails.

flush

public void flush()
           throws IOException

Flush output stream. Any remaining content accumulated in the characters buffer will be written to the underlying writer and writer flushed.

Specified by:

flush in interface Flushable

Overrides:

flush in class OutputStream

Throws:

IOException - if writing operation to underlying target writer fails.

close

public void close()
           throws IOException

Close output stream. Any remaining content accumulated into bytes buffer will be written to the underlying writer via characters buffer. After that Writer.close() will be called.

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Overrides:

close in class OutputStream

Throws:

IOException - if writing or close operation on underlying target writer fails.

processBytesBuffer

private void processBytesBuffer(boolean endOfInput)
                         throws IOException

Decode the contents of input bytes buffer into the characters buffer. If characters buffer overflows invoke flushCharactersBuffer() to commit buffer to underlying writer.

Parameters:

endOfInput - signal that end of input was reached.

Throws:

IOException - if writing operation to underlying target writer fails.

flushCharactersBuffer

private void flushCharactersBuffer()
                            throws IOException

Flush characters buffer to underlying writer.

Throws:

IOException - if write operation on underlying writer fails.