/*
* @(#)SequenceInputStream.java 1.10 95/11/13 Arthur van Hoff
*
* Copyright (c) 1994 Sun Microsystems, Inc. All Rights Reserved.
*
* Permission to use, copy, modify, and distribute this software
* and its documentation for NON-COMMERCIAL purposes and without
* fee is hereby granted provided that this copyright notice
* appears in all copies. Please refer to the file "copyright.html"
* for further important copyright and licensing information.
*
* SUN MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF
* THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
* TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
* PARTICULAR PURPOSE, OR NON-INFRINGEMENT. SUN SHALL NOT BE LIABLE FOR
* ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
* DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.
*/
package java.io;
import java.io.InputStream;
import java.util.Enumeration;
import java.util.Vector;
/**
* Converts a sequence of input streams into an InputStream.
*
* @author Author van Hoff
* @version 1.10, 13 Nov 1995
*/
public
class SequenceInputStream extends InputStream {
Enumeration e;
InputStream in;
/**
* Constructs a new SequenceInputStream initialized to the
* specified list.
* @param e the list
*/
public SequenceInputStream(Enumeration e) {
this.e = e;
try {
nextStream();
} catch (IOException ex) {
// This should never happen
throw new Error("panic");
}
}
/**
* Constructs a new SequenceInputStream initialized to the two
* specified input streams.
* @param s1 the first input stream
* @param s2 the second input stream
*/
public SequenceInputStream(InputStream s1, InputStream s2) {
Vector v = new Vector(2);
v.addElement(s1);
v.addElement(s2);
e = v.elements();
try {
nextStream();
} catch (IOException ex) {
// This should never happen
throw new Error("panic");
}
}
/**
* Continues reading in the next stream if an EOF is reached.
*/
final void nextStream() throws IOException {
if (in != null) {
in.close();
}
in = e.hasMoreElements() ? (InputStream) e.nextElement() : null;
}
/**
* Reads a stream, and upon reaching an EOF, flips to the next
* stream.
*/
public int read() throws IOException {
if (in == null) {
return -1;
}
int c = in.read();
if (c == -1) {
nextStream();
return read();
}
return c;
}
/**
* Reads data into an array of bytes, and upon reaching an EOF,
* flips to the next stream.
* @param buf the buffer into which the data is read
* @param pos the start position of the data
* @param len the maximum number of bytes read
* @exception IOException If an I/O error has occurred.
*/
public int read(byte buf[], int pos, int len) throws IOException {
if (in == null) {
return -1;
}
int n = in.read(buf, pos, len);
if (n <= 0) {
nextStream();
return read(buf, pos, len);
}
return n;
}
/**
* Closes the input stream; flipping to the next stream,
* if an EOF is reached. This method must be called to release
* any resources associated with the stream.
* @exception IOException If an I/O error has occurred.
*/
public void close() throws IOException {
do {
nextStream();
} while (in != null);
}
}