183 lines
6.2 KiB
Java
183 lines
6.2 KiB
Java
/* PipedWriter.java -- Write portion of piped character streams.
|
|
Copyright (C) 1998, 2000, 2001 Free Software Foundation, Inc.
|
|
|
|
This file is part of GNU Classpath.
|
|
|
|
GNU Classpath is free software; you can redistribute it and/or modify
|
|
it under the terms of the GNU General Public License as published by
|
|
the Free Software Foundation; either version 2, or (at your option)
|
|
any later version.
|
|
|
|
GNU Classpath is distributed in the hope that it will be useful, but
|
|
WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with GNU Classpath; see the file COPYING. If not, write to the
|
|
Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
|
|
02111-1307 USA.
|
|
|
|
Linking this library statically or dynamically with other modules is
|
|
making a combined work based on this library. Thus, the terms and
|
|
conditions of the GNU General Public License cover the whole
|
|
combination.
|
|
|
|
As a special exception, the copyright holders of this library give you
|
|
permission to link this library with independent modules to produce an
|
|
executable, regardless of the license terms of these independent
|
|
modules, and to copy and distribute the resulting executable under
|
|
terms of your choice, provided that you also meet, for each linked
|
|
independent module, the terms and conditions of the license of that
|
|
module. An independent module is a module which is not derived from
|
|
or based on this library. If you modify this library, you may extend
|
|
this exception to your version of the library, but you are not
|
|
obligated to do so. If you do not wish to do so, delete this
|
|
exception statement from your version. */
|
|
|
|
|
|
package java.io;
|
|
|
|
// NOTE: This implementation is very similar to that of PipedOutputStream.
|
|
// If you fix a bug in here, chances are you should make a similar change to
|
|
// the PipedOutputStream code.
|
|
|
|
/**
|
|
* This class writes its chars to a <code>PipedReader</code> to
|
|
* which it is connected.
|
|
* <p>
|
|
* It is highly recommended that a <code>PipedWriter</code> and its
|
|
* connected <code>PipedReader</code> be in different threads. If
|
|
* they are in the same thread, read and write operations could deadlock
|
|
* the thread.
|
|
*
|
|
* @author Aaron M. Renn (arenn@urbanophile.com)
|
|
*/
|
|
public class PipedWriter extends Writer
|
|
{
|
|
/** Target PipedReader to which this is connected. Null only if this
|
|
* Writer hasn't been connected yet. */
|
|
PipedReader sink;
|
|
|
|
/** Set to true if close() has been called on this Writer. */
|
|
boolean closed;
|
|
|
|
/** Buffer used to implement single-argument write */
|
|
char[] read_buf = new char[1];
|
|
|
|
/**
|
|
* Create an unconnected PipedWriter. It must be connected
|
|
* to a <code>PipedReader</code> using the <code>connect</code>
|
|
* method prior to writing any data or an exception will be thrown.
|
|
*/
|
|
public PipedWriter()
|
|
{
|
|
}
|
|
|
|
/**
|
|
* Create a new <code>PipedWriter</code> instance
|
|
* to write to the specified <code>PipedReader</code>. This stream
|
|
* is then ready for writing.
|
|
*
|
|
* @param sink The <code>PipedReader</code> to connect this stream to.
|
|
*
|
|
* @exception IOException If <code>sink</code> has already been connected
|
|
* to a different PipedWriter.
|
|
*/
|
|
public PipedWriter(PipedReader sink) throws IOException
|
|
{
|
|
sink.connect(this);
|
|
}
|
|
|
|
/**
|
|
* Connects this object to the specified <code>PipedReader</code>
|
|
* object. This stream will then be ready for writing.
|
|
*
|
|
* @param sink The <code>PipedReader</code> to connect this stream to
|
|
*
|
|
* @exception IOException If the stream has not been connected or has
|
|
* been closed.
|
|
*/
|
|
public void connect(PipedReader sink) throws IOException
|
|
{
|
|
if (sink != null)
|
|
throw new IOException ("Already connected");
|
|
sink.connect(this);
|
|
}
|
|
|
|
/**
|
|
* Write a single char of date to the stream. Note that this method will
|
|
* block if the <code>PipedReader</code> to which this object is
|
|
* connected has a full buffer.
|
|
*
|
|
* @param b The char of data to be written, passed as an <code>int</code>.
|
|
*
|
|
* @exception IOException If the stream has not been connected or has
|
|
* been closed.
|
|
*/
|
|
public void write(int b) throws IOException
|
|
{
|
|
read_buf[0] = (char) (b & 0xffff);
|
|
sink.receive (read_buf, 0, 1);
|
|
}
|
|
|
|
/**
|
|
* This method writes <code>len</code> chars of data from the char array
|
|
* <code>buf</code> starting at index <code>offset</code> in the array
|
|
* to the stream. Note that this method will block if the
|
|
* <code>PipedReader</code> to which this object is connected has
|
|
* a buffer that cannot hold all of the chars to be written.
|
|
*
|
|
* @param buf The array containing chars to write to the stream.
|
|
* @param offset The index into the array to start writing chars from.
|
|
* @param len The number of chars to write.
|
|
*
|
|
* @exception IOException If the stream has not been connected or has
|
|
* been closed.
|
|
*/
|
|
public void write(char[] b, int off, int len) throws IOException
|
|
{
|
|
if (sink == null)
|
|
throw new IOException ("Not connected");
|
|
if (closed)
|
|
throw new IOException ("Pipe closed");
|
|
|
|
sink.receive (b, off, len);
|
|
}
|
|
|
|
/**
|
|
* This method does nothing.
|
|
*
|
|
* @exception IOException If the stream is closed.
|
|
* @specnote You'd think that this method would block until the sink
|
|
* had read all available data. Thats not the case - this method
|
|
* appears to be a no-op?
|
|
*/
|
|
public void flush() throws IOException
|
|
{
|
|
if (closed)
|
|
throw new IOException ("Pipe closed");
|
|
}
|
|
|
|
/**
|
|
* This method closes this stream so that no more data can be written
|
|
* to it. Any further attempts to write to this stream may throw an
|
|
* exception
|
|
*
|
|
* @exception IOException If an error occurs
|
|
*/
|
|
public void close()
|
|
{
|
|
// A close call on an unconnected PipedWriter has no effect.
|
|
if (sink != null)
|
|
{
|
|
closed = true;
|
|
// Notify any waiting readers that the stream is now closed.
|
|
synchronized (sink)
|
|
{
|
|
sink.notifyAll();
|
|
}
|
|
}
|
|
}
|
|
}
|