Class PipedInputStream

protected static final int PIPE_SIZE

The size of the internal buffer used for input/output.

Field Value:

1024

protected byte[] buffer

This is the internal circular buffer used for storing bytes written to the pipe and from which bytes are read by this stream

protected int in

The index into buffer where the next byte from the connected PipedOutputStream will be written. If this variable is equal to out, then the buffer is full. If set to <320, the buffer is empty.

protected int out

This index into the buffer where bytes will be read from.

public PipedInputStream()

Creates a new PipedInputStream that is not connected to a PipedOutputStream. It must be connected before bytes can be read from this stream.

public PipedInputStream(PipedOutputStream source)
            throws IOException

This constructor creates a new PipedInputStream and connects it to the passed in PipedOutputStream. The stream is then ready for reading.

Parameters:

source - The PipedOutputStream to connect this stream to

Throws:

IOException - If source is already connected.

public int available()
            throws IOException

This method returns the number of bytes that can be read from this stream before blocking could occur. This is the number of bytes that are currently unread in the internal circular buffer. Note that once this many additional bytes are read, the stream may block on a subsequent read, but it not guaranteed to block.

Overrides:

available in interface InputStream

Returns:

The number of bytes that can be read before blocking might occur

Throws:

IOException - If an error occurs

public void close()
            throws IOException

This methods closes the stream so that no more data can be read from it.

Specified by:

close in interface Closeable

Overrides:

close in interface InputStream

Throws:

IOException - If an error occurs

public void connect(PipedOutputStream source)
            throws IOException

This method connects this stream to the passed in PipedOutputStream. This stream is then ready for reading. If this stream is already connected or has been previously closed, then an exception is thrown

Parameters:

source - The PipedOutputStream to connect this stream to

Throws:

IOException - If this PipedInputStream or source has been connected already.

public int read()
            throws IOException

This method reads one byte from the stream. -1 is returned to indicated that no bytes can be read because the end of the stream was reached. If the stream is already closed, a -1 will again be returned to indicate the end of the stream.

This method will block if no byte is available to be read.

Overrides:

read in interface InputStream

Returns:

the value of the read byte value, or -1 of the end of the stream was reached

Throws:

IOException - if an error occured

public int read(byte[] buf,
                int offset,
                int len)
            throws IOException

This method reads bytes from the stream into a caller supplied buffer. It starts storing bytes at position offset into the buffer and reads a maximum of len bytes. Note that this method can actually read fewer than len bytes. The actual number of bytes read is returned. A -1 is returned to indicated that no bytes can be read because the end of the stream was reached - ie close() was called on the connected PipedOutputStream.

This method will block if no bytes are available to be read.

Overrides:

read in interface InputStream

Parameters:

buf - The buffer into which bytes will be stored

offset - The index into the buffer at which to start writing.

len - The maximum number of bytes to read.

Throws:

IOException - If close() was called on this Piped InputStream.

protected void receive(int val)
            throws IOException

This method receives a byte of input from the source PipedOutputStream. If the internal circular buffer is full, this method blocks.

Parameters:

val - The byte to write to this stream

Throws:

IOException - if error occurs