java.io

Class PipedInputStream

java.lang.Object

java.io.InputStream

java.io.PipedInputStream

All Implemented Interfaces:

Closeable

public class PipedInputStream
extends InputStream

An input stream that reads its bytes from an output stream to which it is connected.

Data is read and written to an internal buffer. It is highly recommended that the PipedInputStream and connected PipedOutputStream be part of different threads. If they are not, the read and write operations could deadlock their thread.

Author:

Aaron M. Renn (arenn@urbanophile.com)

Constructor Summary

Constructors

Constructor and Description
PipedInputStream() Creates a new PipedInputStream that is not connected to a PipedOutputStream.
PipedInputStream(int pipeSize) Creates a new PipedInputStream of the given size that is not connected to a PipedOutputStream.
PipedInputStream(PipedOutputStream source) This constructor creates a new PipedInputStream and connects it to the passed in PipedOutputStream.
PipedInputStream(PipedOutputStream source, int pipeSize) This constructor creates a new PipedInputStream of the given size and connects it to the passed in PipedOutputStream.

Method Summary

Modifier and Type	Method and Description
int	available() This method returns the number of bytes that can be read from this stream before blocking could occur.
void	close() This methods closes the stream so that no more data can be read from it.
void	connect(PipedOutputStream source) This method connects this stream to the passed in PipedOutputStream.
int	read() This method reads one byte from the stream.
int	read(byte[] buf, int offset, int len) This method reads bytes from the stream into a caller supplied buffer.

Methods inherited from class java.io.InputStream

mark, markSupported, read, reset, skip

Methods inherited from class java.lang.Object

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

Constructor Detail

PipedInputStream

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.

PipedInputStream

public PipedInputStream(int pipeSize)
                 throws IllegalArgumentException

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

Throws:

IllegalArgumentException

Since:

1.6, IllegalArgumentException If pipeSize <= 0.

PipedInputStream

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.

PipedInputStream

public PipedInputStream(PipedOutputStream source,
                        int pipeSize)
                 throws IOException

This constructor creates a new PipedInputStream of the given size 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.

Since:

1.6

Method Detail

available

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 class InputStream

Returns:

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

Throws:

IOException - If an error occurs

close

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 class InputStream

Throws:

IOException - If an error occurs

connect

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.

read

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.

Specified by:

read in class 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

read

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 class 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.

Returns:

The actual number of bytes read, or -1 if end of stream.

Throws:

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