/*
* Copyright (c) 1996, 2006, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*
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package java.io;
/**
* Piped character-output streams.
*
* @author Mark Reinhold
* @since JDK1.1
*/
public class
PipedWriter extends
Writer {
/* REMIND: identification of the read and write sides needs to be
more sophisticated. Either using thread groups (but what about
pipes within a thread?) or using finalization (but it may be a
long time until the next GC). */
private
PipedReader sink;
/* This flag records the open status of this particular writer. It
* is independent of the status flags defined in PipedReader. It is
* used to do a sanity check on connect.
*/
private boolean
closed = false;
/**
* Creates a piped writer connected to the specified piped
* reader. Data characters written to this stream will then be
* available as input from <code>snk</code>.
*
* @param snk The piped reader to connect to.
* @exception IOException if an I/O error occurs.
*/
public
PipedWriter(
PipedReader snk) throws
IOException {
connect(
snk);
}
/**
* Creates a piped writer that is not yet connected to a
* piped reader. It must be connected to a piped reader,
* either by the receiver or the sender, before being used.
*
* @see java.io.PipedReader#connect(java.io.PipedWriter)
* @see java.io.PipedWriter#connect(java.io.PipedReader)
*/
public
PipedWriter() {
}
/**
* Connects this piped writer to a receiver. If this object
* is already connected to some other piped reader, an
* <code>IOException</code> is thrown.
* <p>
* If <code>snk</code> is an unconnected piped reader and
* <code>src</code> is an unconnected piped writer, they may
* be connected by either the call:
* <blockquote><pre>
* src.connect(snk)</pre></blockquote>
* or the call:
* <blockquote><pre>
* snk.connect(src)</pre></blockquote>
* The two calls have the same effect.
*
* @param snk the piped reader to connect to.
* @exception IOException if an I/O error occurs.
*/
public synchronized void
connect(
PipedReader snk) throws
IOException {
if (
snk == null) {
throw new
NullPointerException();
} else if (
sink != null ||
snk.
connected) {
throw new
IOException("Already connected");
} else if (
snk.
closedByReader ||
closed) {
throw new
IOException("Pipe closed");
}
sink =
snk;
snk.
in = -1;
snk.
out = 0;
snk.
connected = true;
}
/**
* Writes the specified <code>char</code> to the piped output stream.
* If a thread was reading data characters from the connected piped input
* stream, but the thread is no longer alive, then an
* <code>IOException</code> is thrown.
* <p>
* Implements the <code>write</code> method of <code>Writer</code>.
*
* @param c the <code>char</code> to be written.
* @exception IOException if the pipe is
* <a href=PipedOutputStream.html#BROKEN> <code>broken</code></a>,
* {@link #connect(java.io.PipedReader) unconnected}, closed
* or an I/O error occurs.
*/
public void
write(int
c) throws
IOException {
if (
sink == null) {
throw new
IOException("Pipe not connected");
}
sink.
receive(
c);
}
/**
* Writes <code>len</code> characters from the specified character array
* starting at offset <code>off</code> to this piped output stream.
* This method blocks until all the characters are written to the output
* stream.
* If a thread was reading data characters from the connected piped input
* stream, but the thread is no longer alive, then an
* <code>IOException</code> is thrown.
*
* @param cbuf the data.
* @param off the start offset in the data.
* @param len the number of characters to write.
* @exception IOException if the pipe is
* <a href=PipedOutputStream.html#BROKEN> <code>broken</code></a>,
* {@link #connect(java.io.PipedReader) unconnected}, closed
* or an I/O error occurs.
*/
public void
write(char
cbuf[], int
off, int
len) throws
IOException {
if (
sink == null) {
throw new
IOException("Pipe not connected");
} else if ((
off |
len | (
off +
len) | (
cbuf.length - (
off +
len))) < 0) {
throw new
IndexOutOfBoundsException();
}
sink.
receive(
cbuf,
off,
len);
}
/**
* Flushes this output stream and forces any buffered output characters
* to be written out.
* This will notify any readers that characters are waiting in the pipe.
*
* @exception IOException if the pipe is closed, or an I/O error occurs.
*/
public synchronized void
flush() throws
IOException {
if (
sink != null) {
if (
sink.
closedByReader ||
closed) {
throw new
IOException("Pipe closed");
}
synchronized (
sink) {
sink.
notifyAll();
}
}
}
/**
* Closes this piped output stream and releases any system resources
* associated with this stream. This stream may no longer be used for
* writing characters.
*
* @exception IOException if an I/O error occurs.
*/
public void
close() throws
IOException {
closed = true;
if (
sink != null) {
sink.
receivedLast();
}
}
}