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PipedReader.java
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1998-09-22
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/*
* @(#)PipedReader.java 1.6 98/07/01
*
* Copyright 1995-1998 by Sun Microsystems, Inc.,
* 901 San Antonio Road, Palo Alto, California, 94303, U.S.A.
* All rights reserved.
*
* This software is the confidential and proprietary information
* of Sun Microsystems, Inc. ("Confidential Information"). You
* shall not disclose such Confidential Information and shall use
* it only in accordance with the terms of the license agreement
* you entered into with Sun.
*/
package java.io;
/**
* Piped character-input streams.
*
* @version 1.6, 98/07/01
* @author Mark Reinhold
* @since JDK1.1
*/
public class PipedReader extends Reader {
PipedInputStream byteSink;
private byte buf[]; /* Conversion buffer */
private int leftOver = 0;
/**
* Create a reader that is not yet connected to a piped writer.
*/
public PipedReader() {
byteSink = new PipedInputStream();
lock = byteSink;
}
/**
* Create a reader for the specified piped character-output stream.
*/
public PipedReader(PipedWriter src) throws IOException {
this();
connect(src);
}
/** Check to make sure that the stream has not been closed */
private void ensureOpen() throws IOException {
if (byteSink == null)
throw new IOException("Stream closed");
}
/**
* Connect the specified piped writer to this reader.
*
* @exception IOException If this reader is already connected
*/
public void connect(PipedWriter src) throws IOException {
synchronized (lock) {
ensureOpen();
src.connect(this);
}
}
/**
* Read characters into a portion of an array.
*
* @param cbuf Destination buffer
* @param off Offset at which to start storing characters
* @param len Maximum number of characters to read
*
* @return The number of characters read, or -1 if the end of the
* stream has been reached
*
* @exception IOException If an I/O error occurs
*/
public int read(char cbuf[], int off, int len) throws IOException {
synchronized (lock) {
ensureOpen();
int blen = leftOver + len * 2;
if ((buf == null) || (buf.length < blen))
buf = new byte[blen];
int nb = byteSink.read(buf, leftOver, blen);
if (nb < 0)
return -1;
nb += leftOver;
for (int i = 0; i < nb; i += 2)
cbuf[i >> 1] = (char) (((buf[i] & 0xff) << 8)
| (buf[i + 1] & 0xff));
if (nb % 2 != 0) {
buf[0] = buf[nb - 1];
leftOver = 1;
}
else
leftOver = 0;
return nb / 2;
}
}
/**
* Close the stream.
*
* @exception IOException If an I/O error occurs
*/
public void close() throws IOException {
synchronized (lock) {
if (byteSink == null)
return;
byteSink.close();
byteSink = null;
}
}
}