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PipedInputStream (Java 2 Platform SE 5.0) - JDK 5 Documentation v1.5.0, Java 2 SDK 英文文档

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JavaTM 2 Platform
Standard Ed. 5.0
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java.io
Class PipedInputStream

java.lang.Object
  extended by java.io.InputStream
      extended by java.io.PipedInputStream
All Implemented Interfaces:
Closeable
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.

Since:
JDK1.0
See Also:
PipedOutputStream

Field Summary
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.
protected static int PIPE_SIZE
          The size of the pipe's circular input buffer.
 
Constructor Summary
PipedInputStream()
          Creates a PipedInputStream so that it is not yet connected.
PipedInputStream(PipedOutputStream src)
          Creates a PipedInputStream so that it is connected to the piped output stream src.
 
Method Summary
 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.
 int read()
          Reads the next byte of data from this piped input stream.
 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  void receive(int b)
          Receives a byte of data.
 
Methods inherited from class java.io.InputStream
mark, markSupported, read, reset, skip
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

PIPE_SIZE

protected static final int PIPE_SIZE
The size of the pipe's circular input buffer.

Since:
JDK1.1
See Also:
Constant Field Values

buffer

protected byte[] buffer
The circular buffer into which incoming data is placed.

Since:
JDK1.1

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

Since:
JDK1.1

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.

Since:
JDK1.1
Constructor Detail

PipedInputStream

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.

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

PipedInputStream

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

See Also:
connect(java.io.PipedOutputStream), PipedOutputStream.connect(java.io.PipedInputStream)
Method Detail

connect

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.

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

receive

protected void receive(int b)
                throws IOException
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.
Since:
JDK1.1

read

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. If no byte is available because the end of the stream has been reached, the value -1 is returned. This method blocks until input data is available, the end of the stream is detected, or an exception is thrown. If a thread was providing data bytes to the connected piped output stream, but the thread is no longer alive, then an IOException is thrown.

Specified by:
read in class InputStream
Returns:
the next byte of data, or -1 if the end of the stream is reached.
Throws:
IOException - if the pipe is broken.

read

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. This method blocks until at least one byte of input is available. If a thread was providing data bytes to the connected piped output stream, but the thread is no longer alive, then an IOException is thrown.

Overrides:
read in class InputStream
Parameters:
b - the buffer into which the data is read.
off - the start offset of the data.
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:
IOException - if an I/O error occurs.
See Also:
InputStream.read()

available

public int available()
              throws IOException
Returns the number of bytes that can be read from this input stream without blocking. This method overrides the available method of the parent class.

Overrides:
available in class InputStream
Returns:
the number of bytes that can be read from this input stream without blocking.
Throws:
IOException - if an I/O error occurs.
Since:
JDK1.0.2

close

public void close()
           throws IOException
Closes this piped input stream and releases any system resources associated with the stream.

Specified by:
close in interface Closeable
Overrides:
close in class InputStream
Throws:
IOException - if an I/O error occurs.
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JavaTM 2 Platform
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For further API reference and developer documentation, see Java 2 SDK SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.

Copyright 2004 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.