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PipedReader (Java 2 Platform SE v1.4.1) - JDK 5 Documentation v1.4.1, Java 2 SDK 英文文档

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JavaTM 2 Platform
Std. Ed. v1.4.1
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java.io
Class PipedReader

java.lang.Object
  |
  +--java.io.Reader
        |
        +--java.io.PipedReader
public class PipedReader
extends Reader

Piped character-input streams.

Since:
JDK1.1

Field Summary
 
Fields inherited from class java.io.Reader
lock
 
Constructor Summary
PipedReader()
          Creates a PipedReader so that it is not yet connected.
PipedReader(PipedWriter src)
          Creates a PipedReader so that it is connected to the piped writer src.
 
Method Summary
 void close()
          Closes this piped stream and releases any system resources associated with the stream.
 void connect(PipedWriter src)
          Causes this piped reader to be connected to the piped writer src.
 int read()
          Reads the next character of data from this piped stream.
 int read(char[] cbuf, int off, int len)
          Reads up to len characters of data from this piped stream into an array of characters.
 boolean ready()
          Tell whether this stream is ready to be read.
 
Methods inherited from class java.io.Reader
mark, markSupported, read, reset, skip
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

PipedReader

public PipedReader(PipedWriter src)
            throws IOException
Creates a PipedReader so that it is connected to the piped writer src. Data 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.

PipedReader

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

See Also:
connect(java.io.PipedWriter), PipedWriter.connect(java.io.PipedReader)
Method Detail

connect

public void connect(PipedWriter src)
             throws IOException
Causes this piped reader to be connected to the piped writer src. If this object is already connected to some other piped writer, an IOException is thrown.

If src is an unconnected piped writer and snk is an unconnected piped reader, 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 writer to connect to.
Throws:
IOException - if an I/O error occurs.

read

public int read()
         throws IOException
Reads the next character of data from this piped stream. If no character 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 characters to the connected piped writer, but the thread is no longer alive, then an IOException is thrown.

Overrides:
read in class Reader
Returns:
the next character of data, or -1 if the end of the stream is reached.
Throws:
IOException - if the pipe is broken.

read

public int read(char[] cbuf,
                int off,
                int len)
         throws IOException
Reads up to len characters of data from this piped stream into an array of characters. Less than len characters will be read if the end of the data stream is reached. This method blocks until at least one character of input is available. If a thread was providing data characters to the connected piped output, but the thread is no longer alive, then an IOException is thrown.

Specified by:
read in class Reader
Parameters:
cbuf - the buffer into which the data is read.
off - the start offset of the data.
len - the maximum number of characters read.
Returns:
the total number of characters 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.

ready

public boolean ready()
              throws IOException
Tell whether this stream is ready to be read. A piped character stream is ready if the circular buffer is not empty.

Overrides:
ready in class Reader
Returns:
True if the next read() is guaranteed not to block for input, false otherwise. Note that returning false does not guarantee that the next read will block.
Throws:
IOException - If an I/O error occurs

close

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

Specified by:
close in class Reader
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 2002 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms.