/* * Copyright (c) 1994, 2006, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code 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 * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */package java.io;import java.io.InputStream;import java.util.Enumeration;import java.util.Vector;/** * A <code>SequenceInputStream</code> represents * the logical concatenation of other input * streams. It starts out with an ordered * collection of input streams and reads from * the first one until end of file is reached, * whereupon it reads from the second one, * and so on, until end of file is reached * on the last of the contained input streams. * * @author Author van Hoff * @since JDK1.0 */publicclass SequenceInputStream extends InputStream { Enumeration e; InputStream in; /** * Initializes a newly created <code>SequenceInputStream</code> * by remembering the argument, which must * be an <code>Enumeration</code> that produces * objects whose run-time type is <code>InputStream</code>. * The input streams that are produced by * the enumeration will be read, in order, * to provide the bytes to be read from this * <code>SequenceInputStream</code>. After * each input stream from the enumeration * is exhausted, it is closed by calling its * <code>close</code> method. * * @param e an enumeration of input streams. * @see java.util.Enumeration */ public SequenceInputStream(Enumeration<? extends InputStream> e) { this.e = e; try { nextStream(); } catch (IOException ex) { // This should never happen throw new Error("panic"); } } /** * Initializes a newly * created <code>SequenceInputStream</code> * by remembering the two arguments, which * will be read in order, first <code>s1</code> * and then <code>s2</code>, to provide the * bytes to be read from this <code>SequenceInputStream</code>. * * @param s1 the first input stream to read. * @param s2 the second input stream to read. */ 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(); } if (e.hasMoreElements()) { in = (InputStream) e.nextElement(); if (in == null) throw new NullPointerException(); } else in = null; } /** * Returns an estimate of the number of bytes that can be read (or * skipped over) from the current underlying input stream without * blocking by the next invocation of a method for the current * underlying input stream. The next invocation might be * the same thread or another thread. A single read or skip of this * many bytes will not block, but may read or skip fewer bytes. * <p> * This method simply calls {@code available} of the current underlying * input stream and returns the result. * * @return an estimate of the number of bytes that can be read (or * skipped over) from the current underlying input stream * without blocking or {@code 0} if this input stream * has been closed by invoking its {@link #close()} method * @exception IOException if an I/O error occurs. * * @since JDK1.1 */ public int available() throws IOException { if(in == null) { return 0; // no way to signal EOF from available() } return in.available(); } /** * Reads the next byte of data from this input stream. The byte is * returned as an <code>int</code> in the range <code>0</code> to * <code>255</code>. If no byte is available because the end of the * stream has been reached, the value <code>-1</code> is returned. * This method blocks until input data is available, the end of the * stream is detected, or an exception is thrown. * <p> * This method * tries to read one character from the current substream. If it * reaches the end of the stream, it calls the <code>close</code> * method of the current substream and begins reading from the next * substream. * * @return the next byte of data, or <code>-1</code> if the end of the * stream is reached. * @exception IOException if an I/O error occurs. */ public int read() throws IOException { if (in == null) { return -1; } int c = in.read(); if (c == -1) { nextStream(); return read(); } return c; } /** * Reads up to <code>len</code> bytes of data from this input stream * into an array of bytes. If <code>len</code> is not zero, the method * blocks until at least 1 byte of input is available; otherwise, no * bytes are read and <code>0</code> is returned. * <p> * The <code>read</code> method of <code>SequenceInputStream</code> * tries to read the data from the current substream. If it fails to * read any characters because the substream has reached the end of * the stream, it calls the <code>close</code> method of the current * substream and begins reading from the next substream. * * @param b the buffer into which the data is read. * @param off the start offset in array <code>b</code> * at which the data is written. * @param len the maximum number of bytes read. * @return int the number of bytes read. * @exception NullPointerException If <code>b</code> is <code>null</code>. * @exception IndexOutOfBoundsException If <code>off</code> is negative, * <code>len</code> is negative, or <code>len</code> is greater than * <code>b.length - off</code> * @exception IOException if an I/O error occurs. */ public int read(byte b[], int off, int len) throws IOException { if (in == null) { return -1; } else if (b == null) { throw new NullPointerException(); } else if (off < 0 || len < 0 || len > b.length - off) { throw new IndexOutOfBoundsException(); } else if (len == 0) { return 0; } int n = in.read(b, off, len); if (n <= 0) { nextStream(); return read(b, off, len); } return n; } /** * Closes this input stream and releases any system resources * associated with the stream. * A closed <code>SequenceInputStream</code> * cannot perform input operations and cannot * be reopened. * <p> * If this stream was created * from an enumeration, all remaining elements * are requested from the enumeration and closed * before the <code>close</code> method returns. * * @exception IOException if an I/O error occurs. */ public void close() throws IOException { do { nextStream(); } while (in != null); }}
/*
* Copyright (c) 1994, 2006, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code 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
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package java.io;
import java.io.InputStream;
import java.util.Enumeration;
import java.util.Vector;
/**
* A <code>SequenceInputStream</code> represents
* the logical concatenation of other input
* streams. It starts out with an ordered
* collection of input streams and reads from
* the first one until end of file is reached,
* whereupon it reads from the second one,
* and so on, until end of file is reached
* on the last of the contained input streams.
*
* @author Author van Hoff
* @since JDK1.0
*/
public
class SequenceInputStream extends InputStream {
Enumeration e;
InputStream in;
/**
* Initializes a newly created <code>SequenceInputStream</code>
* by remembering the argument, which must
* be an <code>Enumeration</code> that produces
* objects whose run-time type is <code>InputStream</code>.
* The input streams that are produced by
* the enumeration will be read, in order,
* to provide the bytes to be read from this
* <code>SequenceInputStream</code>. After
* each input stream from the enumeration
* is exhausted, it is closed by calling its
* <code>close</code> method.
*
* @param e an enumeration of input streams.
* @see java.util.Enumeration
*/
public SequenceInputStream(Enumeration<? extends InputStream> e) {
this.e = e;
try {
nextStream();
} catch (IOException ex) {
// This should never happen
throw new Error("panic");
}
}
/**
* Initializes a newly
* created <code>SequenceInputStream</code>
* by remembering the two arguments, which
* will be read in order, first <code>s1</code>
* and then <code>s2</code>, to provide the
* bytes to be read from this <code>SequenceInputStream</code>.
*
* @param s1 the first input stream to read.
* @param s2 the second input stream to read.
*/
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();
}
if (e.hasMoreElements()) {
in = (InputStream) e.nextElement();
if (in == null)
throw new NullPointerException();
}
else in = null;
}
/**
* Returns an estimate of the number of bytes that can be read (or
* skipped over) from the current underlying input stream without
* blocking by the next invocation of a method for the current
* underlying input stream. The next invocation might be
* the same thread or another thread. A single read or skip of this
* many bytes will not block, but may read or skip fewer bytes.
* <p>
* This method simply calls {@code available} of the current underlying
* input stream and returns the result.
*
* @return an estimate of the number of bytes that can be read (or
* skipped over) from the current underlying input stream
* without blocking or {@code 0} if this input stream
* has been closed by invoking its {@link #close()} method
* @exception IOException if an I/O error occurs.
*
* @since JDK1.1
*/
public int available() throws IOException {
if(in == null) {
return 0; // no way to signal EOF from available()
}
return in.available();
}
/**
* Reads the next byte of data from this input stream. The byte is
* returned as an <code>int</code> in the range <code>0</code> to
* <code>255</code>. If no byte is available because the end of the
* stream has been reached, the value <code>-1</code> is returned.
* This method blocks until input data is available, the end of the
* stream is detected, or an exception is thrown.
* <p>
* This method
* tries to read one character from the current substream. If it
* reaches the end of the stream, it calls the <code>close</code>
* method of the current substream and begins reading from the next
* substream.
*
* @return the next byte of data, or <code>-1</code> if the end of the
* stream is reached.
* @exception IOException if an I/O error occurs.
*/
public int read() throws IOException {
if (in == null) {
return -1;
}
int c = in.read();
if (c == -1) {
nextStream();
return read();
}
return c;
}
/**
* Reads up to <code>len</code> bytes of data from this input stream
* into an array of bytes. If <code>len</code> is not zero, the method
* blocks until at least 1 byte of input is available; otherwise, no
* bytes are read and <code>0</code> is returned.
* <p>
* The <code>read</code> method of <code>SequenceInputStream</code>
* tries to read the data from the current substream. If it fails to
* read any characters because the substream has reached the end of
* the stream, it calls the <code>close</code> method of the current
* substream and begins reading from the next substream.
*
* @param b the buffer into which the data is read.
* @param off the start offset in array <code>b</code>
* at which the data is written.
* @param len the maximum number of bytes read.
* @return int the number of bytes read.
* @exception NullPointerException If <code>b</code> is <code>null</code>.
* @exception IndexOutOfBoundsException If <code>off</code> is negative,
* <code>len</code> is negative, or <code>len</code> is greater than
* <code>b.length - off</code>
* @exception IOException if an I/O error occurs.
*/
public int read(byte b[], int off, int len) throws IOException {
if (in == null) {
return -1;
} else if (b == null) {
throw new NullPointerException();
} else if (off < 0 || len < 0 || len > b.length - off) {
throw new IndexOutOfBoundsException();
} else if (len == 0) {
return 0;
}
int n = in.read(b, off, len);
if (n <= 0) {
nextStream();
return read(b, off, len);
}
return n;
}
/**
* Closes this input stream and releases any system resources
* associated with the stream.
* A closed <code>SequenceInputStream</code>
* cannot perform input operations and cannot
* be reopened.
* <p>
* If this stream was created
* from an enumeration, all remaining elements
* are requested from the enumeration and closed
* before the <code>close</code> method returns.
*
* @exception IOException if an I/O error occurs.
*/
public void close() throws IOException {
do {
nextStream();
} while (in != null);
}
}