js.io

Class ReaderInputStream

java.lang.Object

java.io.InputStream

js.io.ReaderInputStream

All Implemented Interfaces:

Closeable, AutoCloseable

public class ReaderInputStream
extends InputStream

Adapter for characters reader to input bytes stream encoded UTF-8. This class allows for reading UTF-8 bytes stream from a characters source. At the core of this reading process there is CharsetEncoder that takes a sequence of 16-bit Unicode characters and transform it into a sequence of bytes in UTF-8. Charset encoder uses two buffers: charactersBuffer for characters source - updated by wrapped reader, and bytesBuffer where encoder stores encoding result. All input stream read operations takes bytes from the bytes buffer; if bytes buffer is empty delegates fillBytesBuffer().

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 output for the encoder.
private static int	CHARACTERS_BUFFER_SIZE Size of internal characters buffer.
private CharBuffer	charactersBuffer Characters buffer used as input for the encoder.
private CharsetEncoder	encoder Encoder for UTF-8 character set.
private boolean	endOfInput Flag true when end of file is detected by fillBytesBuffer().
private static int	EOF Constant for end of file mark.
private CoderResult	lastEncoderResult Cache last encoder result.
private Reader	reader Source reader.

Constructor Summary

Constructors

Constructor and Description
ReaderInputStream(Reader reader) Construct a new input stream for source reader, using UTF-8 character encoding.

Method Summary

Modifier and Type	Method and Description
void	close() Close the stream.
private void	fillBytesBuffer() Encode characters from charactersBuffer and store UTF-8 bytes into bytesBuffer.
int	read() Reads the next byte of data from the input stream.
int	read(byte[] b) Reads some number of bytes from the input stream and stores them into the buffer array b.
int	read(byte[] bytes, int off, int len) Reads up to len bytes of data from the input stream into an array of bytes.

Methods inherited from class java.io.InputStream

available, mark, markSupported, reset, skip

Methods inherited from class java.lang.Object

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

Field Detail

CHARACTERS_BUFFER_SIZE

private static final int CHARACTERS_BUFFER_SIZE

Size of internal characters buffer. See charactersBuffer.

See Also:

Constant Field Values

BYTES_BUFFER_SIZE

private static final int BYTES_BUFFER_SIZE

Size of internal bytes buffer. See bytesBuffer.

See Also:

Constant Field Values

EOF

private static final int EOF

Constant for end of file mark.

See Also:

Constant Field Values

encoder

private final CharsetEncoder encoder

Encoder for UTF-8 character set. Encoder transforms a sequence of 16-bit Unicode characters into a sequence of bytes in a specific charset, in this case UTF-8. Basically encoder reads from charactersBuffer and writes UTF-8 encoded bytes into bytesBuffer.

charactersBuffer

private final CharBuffer charactersBuffer

Characters buffer used as input for the encoder. Encoder reads characters from this buffer and stores encoded bytes into bytesBuffer.

bytesBuffer

private final ByteBuffer bytesBuffer

Bytes buffer used as output for the encoder. Encoder stores encoded bytes into this buffer; all input stream read operations takes bytes from this buffer.

reader

private final Reader reader

Source reader.

lastEncoderResult

private CoderResult lastEncoderResult

Cache last encoder result.

endOfInput

private boolean endOfInput

Flag true when end of file is detected by fillBytesBuffer().

Constructor Detail

ReaderInputStream

public ReaderInputStream(Reader reader)

Construct a new input stream for source reader, using UTF-8 character encoding.

Parameters:

reader - source reader.

Method Detail

read

public int read(byte[] bytes,
                int off,
                int len)
         throws IOException

Reads up to len bytes of data from the input stream into an array of bytes. Returns the number of bytes read or -1 if end of stream was reached.

This method simple copy bytesBuffer into given bytes buffer. If stream buffer is empty delegates fillBytesBuffer() to fill it from underlying reader.

Overrides:

read in class InputStream

Parameters:

bytes - the bytes buffer to read into,

off - the offset to start reading bytes into,

len - the number of bytes to read.

Returns:

the number of bytes read or -1 if the end of the stream has been reached.

Throws:

IllegalArgumentException - if bytes argument is null.

IndexOutOfBoundsException - if offset or length is negative or sum of offset and length exceeds buffer size.

IOException - if read from underlying source fails.

read

public int read(byte[] b)
         throws IOException

Reads some number of bytes from the input stream and stores them into the buffer array b. Returns the number of bytes read or -1 if end of stream was reached.

This method simple copy bytesBuffer into given bytes buffer. If stream buffer is empty delegates fillBytesBuffer() to fill it from underlying reader.

Overrides:

read in class InputStream

Parameters:

b - the byte array to read into

Returns:

the number of bytes read or -1 if the end of the stream has been reached.

Throws:

IOException - if read from underlying source fails.

read

public int read()
         throws IOException

Reads the next byte of data from the input stream. If internal stream buffer contains at least one byte just return it. Otherwise delegates fillBytesBuffer() to add more bytes, bytes that are in the end read and encoded from source reader.

Specified by:

read in class InputStream

Returns:

either the byte read or -1 if the end of the stream has been reached.

Throws:

IOException - if read from underlying source reader fails.

close

public void close()
           throws IOException

Close the stream. This method will cause the underlying Reader to be closed.

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Overrides:

close in class InputStream

Throws:

IOException - if underlying source reader closing fails.

fillBytesBuffer

private void fillBytesBuffer()
                      throws IOException

Encode characters from charactersBuffer and store UTF-8 bytes into bytesBuffer. If characters buffer is underflow takes care to read more characters from underlying source reader.

Throws:

IOException - if read from underlying source reader fails.

See Also:

charactersBuffer, bytesBuffer