public class PipedInputStream extends InputStream
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.
PipedOutputStream
protected static final int PIPE_SIZE
The default size of the pipe's circular input buffer.
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 PipedInputStream(PipedOutputStream src) throws IOException
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.
src
- the stream to connect to.IOException
- if an I/O error occurs.public PipedInputStream(PipedOutputStream src, int pipeSize) throws IOException
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.
src
- the stream to connect to.pipeSize
- the size of the pipe's buffer.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.
pipeSize
- the size of the pipe's buffer.IllegalArgumentException
- if pipeSize <= 0
.public void connect(PipedOutputStream src) throws IOException
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.
src
- The piped output stream to connect to.IOException
- if an I/O error occurs.protected void receive(int b) throws IOException
Receives a byte of data. This method will block if no input is available.
b
- the byte being receivedIOException
- If the pipe is broken
, unconnected
, closed, or if an I/O error occurs.public int read() throws IOException
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.
read
in class InputStream
-1
if the end of the stream is reached.IOException
- if the pipe is unconnected
, broken
, closed, or if an I/O error occurs.public int read(byte[] b, int off, int len) throws IOException
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.
read
in class InputStream
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.-1
if there is no more data because the end of the stream has been reached.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.InputStream.read()
public int available() throws IOException
Returns the number of bytes that can be read from this input stream without blocking.
available
in class InputStream
0
if this input stream has been closed by invoking its close()
method, or if the pipe is unconnected
, or broken
.IOException
- if an I/O error occurs.public void close() throws IOException
Closes this piped input stream and releases any system resources associated with the stream.
close
in interface Closeable
close
in interface AutoCloseable
close
in class InputStream
IOException
- if an I/O error occurs.
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Documentation extracted from Debian's OpenJDK Development Kit package.
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