public class

PipedInputStream

extends InputStream
java.lang.Object
   ↳ java.io.InputStream
     ↳ java.io.PipedInputStream

Class Overview

A piped input stream should be connected to a piped output stream; the piped input stream then provides whatever data bytes are written to the piped output stream. Typically, data is read from a PipedInputStream object by one thread and data is written to the corresponding PipedOutputStream by some other thread. Attempting to use both objects from a single thread is not recommended, as it may deadlock the thread. The piped input stream contains a buffer, decoupling read operations from write operations, within limits. A pipe is said to be broken if a thread that was providing data bytes to the connected piped output stream is no longer alive.

See Also

Summary

Constants
int PIPE_SIZE The default size of the pipe's circular input buffer.
Fields
protected byte[] buffer The circular buffer into which incoming data is placed.
protected int in The index of the position in the circular buffer at which the next byte of data will be stored when received from the connected piped output stream.
protected int out The index of the position in the circular buffer at which the next byte of data will be read by this piped input stream.
Public Constructors
PipedInputStream(PipedOutputStream src)
Creates a PipedInputStream so that it is connected to the piped output stream src.
PipedInputStream(PipedOutputStream src, int pipeSize)
Creates a PipedInputStream so that it is connected to the piped output stream src and uses the specified pipe size for the pipe's buffer.
PipedInputStream()
Creates a PipedInputStream so that it is not yet connected.
PipedInputStream(int pipeSize)
Creates a PipedInputStream so that it is not yet connected and uses the specified pipe size for the pipe's buffer.
Public Methods
synchronized int available()
Returns the number of bytes that can be read from this input stream without blocking.
void close()
Closes this piped input stream and releases any system resources associated with the stream.
void connect(PipedOutputStream src)
Causes this piped input stream to be connected to the piped output stream src.
synchronized int read()
Reads the next byte of data from this piped input stream.
synchronized int read(byte[] b, int off, int len)
Reads up to len bytes of data from this piped input stream into an array of bytes.
Protected Methods
synchronized void receive(int b)
Receives a byte of data.
[Expand]
Inherited Methods
From class java.io.InputStream
From class java.lang.Object
From interface java.io.Closeable

Constants

protected static final int PIPE_SIZE

The default size of the pipe's circular input buffer.

Constant Value: 1024 (0x00000400)

Fields

protected byte[] buffer

The circular buffer into which incoming data is placed.

protected int in

The index of the position in the circular buffer at which the next byte of data will be stored when received from the connected piped output stream. in<0 implies the buffer is empty, in==out implies the buffer is full

protected int out

The index of the position in the circular buffer at which the next byte of data will be read by this piped input stream.

Public Constructors

public PipedInputStream (PipedOutputStream src)

Creates a PipedInputStream so that it is connected to the piped output stream src. Data bytes written to src will then be available as input from this stream.

Parameters
src the stream to connect to.
Throws
IOException if an I/O error occurs.

public PipedInputStream (PipedOutputStream src, int pipeSize)

Creates a PipedInputStream so that it is connected to the piped output stream src and uses the specified pipe size for the pipe's buffer. Data bytes written to src will then be available as input from this stream.

Parameters
src the stream to connect to.
pipeSize the size of the pipe's buffer.
Throws
IOException if an I/O error occurs.
IllegalArgumentException if pipeSize <= 0.

public PipedInputStream ()

Creates a PipedInputStream so that it is not yet connected. It must be connected to a PipedOutputStream before being used.

public PipedInputStream (int pipeSize)

Creates a PipedInputStream so that it is not yet connected and uses the specified pipe size for the pipe's buffer. It must be connected to a PipedOutputStream before being used.

Parameters
pipeSize the size of the pipe's buffer.
Throws
IllegalArgumentException if pipeSize <= 0.

Public Methods

public synchronized int available ()

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

Returns
  • the number of bytes that can be read from this input stream without blocking, or 0 if this input stream has been closed by invoking its close() method, or if the pipe is unconnected, or broken.
Throws
IOException if an I/O error occurs.

public void close ()

Closes this piped input stream and releases any system resources associated with the stream.

Throws
IOException if an I/O error occurs.

public void connect (PipedOutputStream src)

Causes this piped input stream to be connected to the piped output stream src. If this object is already connected to some other piped output stream, an IOException is thrown.

If src is an unconnected piped output stream and snk is an unconnected piped input stream, they may be connected by either the call: 

snk.connect(src)

or the call: 

src.connect(snk)

The two calls have the same effect.

Parameters
src The piped output stream to connect to.
Throws
IOException if an I/O error occurs.

public synchronized int read ()

Reads the next byte of data from this piped input stream. The value byte is returned as an int in the range 0 to 255. This method blocks until input data is available, the end of the stream is detected, or an exception is thrown.

Returns
  • the next byte of data, or -1 if the end of the stream is reached.
Throws
IOException if the pipe is unconnected, broken, closed, or if an I/O error occurs.

public synchronized int read (byte[] b, int off, int len)

Reads up to len bytes of data from this piped input stream into an array of bytes. Less than len bytes will be read if the end of the data stream is reached or if len exceeds the pipe's buffer size. If len is zero, then no bytes are read and 0 is returned; otherwise, the method blocks until at least 1 byte of input is available, end of the stream has been detected, or an exception is thrown.

Parameters
b the buffer into which the data is read.
off the start offset in the destination array b
len the maximum number of bytes 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
NullPointerException If b is null.
IndexOutOfBoundsException If off is negative, len is negative, or len is greater than b.length - off
IOException if the pipe is broken, unconnected, closed, or if an I/O error occurs.

Protected Methods

protected synchronized void receive (int b)

Receives a byte of data. This method will block if no input is available.

Parameters
b the byte being received
Throws
IOException If the pipe is broken, unconnected, closed, or if an I/O error occurs.