com.sun.cdc.io
Class BufferedConnectionAdapter

java.lang.Object
  com.sun.cdc.io.ConnectionBaseAdapter
      com.sun.cdc.io.BufferedConnectionAdapter

All Implemented Interfaces:

ConnectionBaseInterface, Connection, InputConnection, OutputConnection, StreamConnection

Direct Known Subclasses:

Protocol

public abstract class BufferedConnectionAdapter
extends ConnectionBaseAdapter

This class adds read buffering to the ConnectionBaseAdapter.

Implements InputStream.available(), however a subclass must specify a buffer size greater than 0 and override readBytesNonBlocking(byte[], int, int) in order to for available to work properly.

Field Summary

protected byte[]	buf The internal buffer array where the data is stored.
protected int	count The index one greater than the index of the last valid byte in the buffer.
protected boolean	eof The end of file flag.
protected int	pos The current position in the buffer.

Fields inherited from class com.sun.cdc.io.ConnectionBaseAdapter

connectionOpen, iStreams, maxIStreams, maxOStreams, oStreams

Constructor Summary

protected

BufferedConnectionAdapter(int sizeOfBuffer) Initializes the connection.

Method Summary

int	available() Returns the number of bytes that can be read (or skipped over) from this input stream without blocking by the next caller of a method for this input stream.
protected abstract int	nonBufferedRead(byte[] b, int off, int len) Reads up to len bytes of data from the input stream into an array of bytes, blocks until at least one byte is available.
int	readBytes(byte[] b, int off, int len) Reads up to len bytes of data from the input stream into an array of bytes, blocks until at least one byte is available.
protected int	readBytesNonBlocking(byte[] b, int off, int len) Reads up to len bytes of data from the input stream into an array of bytes, but does not block if no bytes available.

Methods inherited from class com.sun.cdc.io.ConnectionBaseAdapter

checkForPermission, close, closeInputStream, closeOutputStream, connect, disconnect, ensureNoStreamsOpen, ensureOpen, flush, mark, markSupported, openDataInputStream, openDataOutputStream, openInputStream, openOutputStream, openPrim, openPrim, reset, writeBytes

Methods inherited from class java.lang.Object

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

Field Detail

eof

protected boolean eof

The end of file flag.

buf

protected byte[] buf

The internal buffer array where the data is stored. When necessary, it may be replaced by another array of a different size.

count

protected int count

The index one greater than the index of the last valid byte in the buffer. This value is always in the range 0 through buf.length; elements buf[0] through buf[count-1] contain buffered input data obtained from the underlying input stream.

pos

protected int pos

The current position in the buffer. This is the index of the next character to be read from the buf array.

This value is always in the range 0 through count. If it is less than count, then buf[pos] is the next byte to be supplied as input; if it is equal to count, then the next read or skip operation will require more bytes to be read from the contained input stream.

Constructor Detail

BufferedConnectionAdapter

protected BufferedConnectionAdapter(int sizeOfBuffer)

Initializes the connection.

Parameters:

sizeOfBuffer - size of the internal buffer or 0 for no buffer

Method Detail

readBytes

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

Reads up to len bytes of data from the input stream into an array of bytes, blocks until at least one byte is available.

Do not use this method if openInputStream has been called since the input stream may be buffering data.

Specified by:

readBytes in class ConnectionBaseAdapter

Parameters:

b - the buffer into which the data is read.

off - the start offset in array b at which the data is written.

len - the maximum number of bytes to read.

Returns:

the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.

Throws:

IOException - if an I/O error occurs.

readBytesNonBlocking

protected int readBytesNonBlocking(byte[] b,
                                   int off,
                                   int len)
                            throws IOException

Reads up to len bytes of data from the input stream into an array of bytes, but does not block if no bytes available. A subclass should implement this to so the available method on the InputStream will be useful. Sets the eof field of the connection when the native read returns -1.

The readBytesNonBlocking method of ConnectionBaseAdapter does nothing and returns 0.

Parameters:

b - the buffer into which the data is read.

off - the start offset in array b at which the data is written.

len - the maximum number of bytes to read.

Returns:

the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.

Throws:

IOException - if an I/O error occurs.

available

public int available()
              throws IOException

Returns the number of bytes that can be read (or skipped over) from this input stream without blocking by the next caller of a method for this input stream. The next caller might be the same thread or another thread.

The available method always returns 0 if readBytesNonBlocking(byte[], int, int) is not overridden by the subclass or there is not buffer.

Overrides:

available in class ConnectionBaseAdapter

Returns:

the number of bytes that can be read from this input stream without blocking.

Throws:

IOException - if an I/O error occurs.

nonBufferedRead

protected abstract int nonBufferedRead(byte[] b,
                                       int off,
                                       int len)
                                throws IOException

Reads up to len bytes of data from the input stream into an array of bytes, blocks until at least one byte is available. Sets the eof field of the connection when there is no more data in the stream to read.

Parameters:

b - the buffer into which the data is read.

off - the start offset in array b at which the data is written.

len - the maximum number of bytes to read.

Returns:

the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.

Throws:

IOException - if an I/O error occurs.