PipedInputStream
public class PipedInputStream
extends InputStream
java.lang.Object | ||
↳ | java.io.InputStream | |
↳ | java.io.PipedInputStream |
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 | |
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int | PIPE_SIZE The default size of the pipe's circular input buffer. |
Fields | |
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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 | |
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PipedInputStream() Creates a | |
PipedInputStream(int pipeSize) Creates a | |
PipedInputStream(PipedOutputStream src) Creates a | |
PipedInputStream(PipedOutputStream src, int pipeSize) Creates a |
Public methods | |
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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 |
int | read() Reads the next byte of data from this piped input stream. |
int | read(byte[] b, int off, int len) Reads up to |
Protected methods | |
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void | receive(int b) Receives a byte of data. |
Inherited methods | |
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Constants
PIPE_SIZE
protected static final int PIPE_SIZE
The default size of the pipe's circular input buffer.
Constant Value: 1024 (0x00000400)
Fields
buffer
protected byte[] buffer
The circular buffer into which incoming data is placed.
in
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
out
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
public PipedInputStream ()
Creates a PipedInputStream
so that it is not yet connected. It must be connected to a PipedOutputStream
before being used.
PipedInputStream
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 | |
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pipeSize | int : the size of the pipe's buffer. |
Throws | |
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IllegalArgumentException | if pipeSize <= 0 . |
PipedInputStream
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 | |
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src | PipedOutputStream : the stream to connect to. |
Throws | |
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IOException | if an I/O error occurs. |
PipedInputStream
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 | |
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src | PipedOutputStream : the stream to connect to. |
pipeSize | int : the size of the pipe's buffer. |
Throws | |
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IOException | if an I/O error occurs. |
IllegalArgumentException | if pipeSize <= 0 . |
Public methods
available
public int available ()
Returns the number of bytes that can be read from this input stream without blocking.
Returns | |
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int | 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 | |
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IOException | if an I/O error occurs. |
close
public void close ()
Closes this piped input stream and releases any system resources associated with the stream.
Throws | |
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IOException | if an I/O error occurs. |
connect
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 | |
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src | PipedOutputStream : The piped output stream to connect to. |
Throws | |
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IOException | if an I/O error occurs. |
read
public 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 | |
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int | the next byte of data, or -1 if the end of the stream is reached. |
Throws | |
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IOException | if the pipe is unconnected , broken , closed, or if an I/O error occurs. |
read
public 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 | |
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b | byte : the buffer into which the data is read. |
off | int : the start offset in the destination array b |
len | int : the maximum number of bytes read. |
Returns | |
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int | 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 | |
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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
receive
protected void receive (int b)
Receives a byte of data. This method will block if no input is available.
Parameters | |
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b | int : the byte being received |
Throws | |
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IOException | If the pipe is broken , unconnected , closed, or if an I/O error occurs. |