191 lines
6.9 KiB
Java
191 lines
6.9 KiB
Java
/*
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* Copyright (c) 1996, 2016, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package java.io;
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/**
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* Piped character-output streams.
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*
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* @author Mark Reinhold
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* @since 1.1
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*/
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public class PipedWriter extends Writer {
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/* REMIND: identification of the read and write sides needs to be
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more sophisticated. Either using thread groups (but what about
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pipes within a thread?) or using finalization (but it may be a
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long time until the next GC). */
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private PipedReader sink;
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/* This flag records the open status of this particular writer. It
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* is independent of the status flags defined in PipedReader. It is
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* used to do a sanity check on connect.
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*/
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private boolean closed = false;
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/**
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* Creates a piped writer connected to the specified piped
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* reader. Data characters written to this stream will then be
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* available as input from <code>snk</code>.
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*
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* @param snk The piped reader to connect to.
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* @exception IOException if an I/O error occurs.
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*/
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public PipedWriter(PipedReader snk) throws IOException {
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connect(snk);
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}
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/**
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* Creates a piped writer that is not yet connected to a
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* piped reader. It must be connected to a piped reader,
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* either by the receiver or the sender, before being used.
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*
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* @see java.io.PipedReader#connect(java.io.PipedWriter)
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* @see java.io.PipedWriter#connect(java.io.PipedReader)
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*/
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public PipedWriter() {
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}
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/**
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* Connects this piped writer to a receiver. If this object
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* is already connected to some other piped reader, an
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* <code>IOException</code> is thrown.
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* <p>
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* If <code>snk</code> is an unconnected piped reader and
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* <code>src</code> is an unconnected piped writer, they may
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* be connected by either the call:
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* <blockquote><pre>
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* src.connect(snk)</pre></blockquote>
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* or the call:
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* <blockquote><pre>
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* snk.connect(src)</pre></blockquote>
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* The two calls have the same effect.
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*
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* @param snk the piped reader to connect to.
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* @exception IOException if an I/O error occurs.
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*/
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public synchronized void connect(PipedReader snk) throws IOException {
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if (snk == null) {
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throw new NullPointerException();
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} else if (sink != null || snk.connected) {
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throw new IOException("Already connected");
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} else if (snk.closedByReader || closed) {
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throw new IOException("Pipe closed");
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}
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sink = snk;
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snk.in = -1;
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snk.out = 0;
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snk.connected = true;
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}
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/**
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* Writes the specified <code>char</code> to the piped output stream.
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* If a thread was reading data characters from the connected piped input
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* stream, but the thread is no longer alive, then an
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* <code>IOException</code> is thrown.
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* <p>
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* Implements the <code>write</code> method of <code>Writer</code>.
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*
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* @param c the <code>char</code> to be written.
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* @exception IOException if the pipe is
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* <a href=PipedOutputStream.html#BROKEN> <code>broken</code></a>,
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* {@link #connect(java.io.PipedReader) unconnected}, closed
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* or an I/O error occurs.
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*/
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public void write(int c) throws IOException {
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if (sink == null) {
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throw new IOException("Pipe not connected");
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}
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sink.receive(c);
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}
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/**
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* Writes {@code len} characters from the specified character array
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* starting at offset {@code off} to this piped output stream.
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* This method blocks until all the characters are written to the output
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* stream.
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* If a thread was reading data characters from the connected piped input
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* stream, but the thread is no longer alive, then an
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* {@code IOException} is thrown.
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*
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* @param cbuf the data.
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* @param off the start offset in the data.
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* @param len the number of characters to write.
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*
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* @throws IndexOutOfBoundsException
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* If {@code off} is negative, or {@code len} is negative,
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* or {@code off + len} is negative or greater than the length
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* of the given array
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*
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* @throws IOException if the pipe is
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* <a href=PipedOutputStream.html#BROKEN><code>broken</code></a>,
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* {@link #connect(java.io.PipedReader) unconnected}, closed
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* or an I/O error occurs.
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*/
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public void write(char cbuf[], int off, int len) throws IOException {
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if (sink == null) {
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throw new IOException("Pipe not connected");
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} else if ((off | len | (off + len) | (cbuf.length - (off + len))) < 0) {
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throw new IndexOutOfBoundsException();
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}
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sink.receive(cbuf, off, len);
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}
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/**
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* Flushes this output stream and forces any buffered output characters
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* to be written out.
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* This will notify any readers that characters are waiting in the pipe.
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*
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* @exception IOException if the pipe is closed, or an I/O error occurs.
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*/
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public synchronized void flush() throws IOException {
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if (sink != null) {
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if (sink.closedByReader || closed) {
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throw new IOException("Pipe closed");
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}
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synchronized (sink) {
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sink.notifyAll();
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}
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}
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}
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/**
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* Closes this piped output stream and releases any system resources
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* associated with this stream. This stream may no longer be used for
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* writing characters.
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*
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* @exception IOException if an I/O error occurs.
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*/
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public void close() throws IOException {
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closed = true;
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if (sink != null) {
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sink.receivedLast();
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}
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}
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}
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