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/*
========== licence begin GPL
Copyright (C) 2002-2003 SAP AG
This program 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
of the License, or (at your option) any later version.
This program 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 this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
========== licence end
*/
package com.sap.dbtech.util;
import java.io.*;
public class JoinReader
extends Reader
{
protected Reader [] instreams;
protected Reader currentStream;
protected int currentIndex = -1;
public JoinReader (Reader[] instreams)
{
this.instreams = instreams;
this.nextStream ();
}
protected void nextStream ()
{
++this.currentIndex;
if (this.currentIndex >= this.instreams.length) {
this.currentStream = null;
}
else {
this.currentStream = this.instreams [this.currentIndex];
}
}
public int read(char b[], int off, int len)
throws IOException
{
int result = 0;
int chunkLen;
while ((this.currentStream != null) && (len > 0)) {
chunkLen = this.currentStream.read (b, off, len);
if (chunkLen == -1) {
this.nextStream ();
}
else {
off += chunkLen;
len -= chunkLen;
result += chunkLen;
}
}
if ((result == 0) && (this.currentStream == null)) {
result = -1;
}
return result;
}
public int read()
throws IOException
{
int result = 0;
while (this.currentStream != null) {
result = this.currentStream.read ();
if (result == -1) {
this.nextStream ();
}
}
if (this.currentStream == null) {
result = -1;
}
return result;
}
/**
* Closes this input stream and releases any system resources associated
* with the stream.
*
* <p> The <code>close</code> method of <code>InputStream</code> does
* nothing.
*
* @exception IOException if an I/O error occurs.
*/
public void close()
{
for (int i = this.currentIndex; i < this.instreams.length; ++i) {
try {
if (this.instreams [i] != null) {
this.instreams [i].close ();
}
}
catch (IOException exc) {
// ignore
}
}
}
/**
* Tests if this input stream supports the <code>mark</code> and
* <code>reset</code> methods. The <code>markSupported</code> method of
* <code>InputStream</code> returns <code>false</code>.
*
* @return <code>true</code> if this true type supports the mark and reset
* method; <code>false</code> otherwise.
* @see java.io.InputStream#mark(int)
* @see java.io.InputStream#reset()
*/
public boolean markSupported()
{
return false;
}
}
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