/*
* @(#)UniversalFilterInputStream.java 1.12 06/10/10
*
* Copyright 1990-2008 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
*
* This program 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.
*
* 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 version 2 for more details (a copy is
* included at /legal/license.txt).
*
* 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 Sun Microsystems, Inc., 4150 Network Circle, Santa
* Clara, CA 95054 or visit www.sun.com if you need additional
* information or have any questions.
*
*/
package com.sun.cdc.io.j2me;
import java.io.*;
import javax.microedition.io.*;
/**
* This class is a an extension of the J2SE class FilterInputStream. It has the
* same interface as FilterInputStream but in addition it extends
* UniversalInputStream and so provided all the functionality therein. This class
* is useful to convert a regular InputStream into a UniversalInputStream.
*
* @author Nik Shaylor
* @version 1.0 1/7/2000
*/
public
class UniversalFilterInputStream extends UniversalInputStream {
/**
* The input stream to be filtered.
*/
protected InputStream in;
/**
* A flag to show if reset() will seek to the start of the data
*/
protected boolean marked = false;
/**
* Connection object that needs closing
*/
protected Connection con;
/**
* Creates a <code>UniversalFilterInputStream</code>
* by assigning the argument <code>in</code>
* to the field <code>this.in</code> so as
* to remember it for later use.
*
* @param in the underlying input stream.
*/
public UniversalFilterInputStream(InputStream in) {
this.in = in;
if(in.markSupported()) {
try {
in.mark(in.available());
marked = true;
} catch(IOException x) {
}
}
}
/**
* Creates a <code>UniversalFilterInputStream</code>
* by assigning the argument <code>in</code>
* to the field <code>this.in</code> so as
* to remember it for later use. Also accepts a Connection
* parameter that must be closed after the stream is closed
*
* @param con the connection which must be closed when this stream is closed
*
* @param in the underlying input stream.
*/
public UniversalFilterInputStream(Connection con, InputStream in) {
this(in);
this.con = con;
}
/**
* Reads the next byte of data from this input stream. The value
* 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
* simply performs <code>in.read()</code> and returns the result.
*
* @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.
* @see javax.microedition.io.UniversalFilterInputStream#in
*/
public int read() throws IOException {
return in.read();
}
/**
* Reads up to <code>len</code> bytes of data from this input stream
* into an array of bytes. This method blocks until some input is
* available.
* <p>
* This method simply performs <code>in.read(b, off, len)</code>
* and returns the result.
*
* @param b the buffer into which the data is read.
* @param off the start offset of the data.
* @param len the maximum number of bytes read.
* @return the total number of bytes read into the buffer, or
* <code>-1</code> if there is no more data because the end of
* the stream has been reached.
* @exception IOException if an I/O error occurs.
* @see javax.microedition.io.UniversalFilterInputStream#in
*/
public int read(byte b[], int off, int len) throws IOException {
return in.read(b, off, len);
}
/**
* Skips over and discards <code>n</code> bytes of data from the
* input stream. The <code>skip</code> method may, for a variety of
* reasons, end up skipping over some smaller number of bytes,
* possibly <code>0</code>. The actual number of bytes skipped is
* returned.
* <p>
* This method
* simply performs <code>in.skip(n)</code>.
*
* @param n the number of bytes to be skipped.
* @return the actual number of bytes skipped.
* @exception IOException if an I/O error occurs.
*/
public long skip(long n) throws IOException {
return in.skip(n);
}
/**
* Returns the number of bytes that can be read from this input
* stream without blocking.
* <p>
* This method
* simply performs <code>in.available(n)</code> and
* returns the result.
*
* @return the number of bytes that can be read from the input stream
* without blocking.
* @exception IOException if an I/O error occurs.
* @see javax.microedition.io.UniversalFilterInputStream#in
*/
public int available() throws IOException {
return in.available();
}
/**
* Closes this input stream and releases any system resources
* associated with the stream.
* This
* method simply performs <code>in.close()</code>.
*
* @exception IOException if an I/O error occurs.
* @see javax.microedition.io.UniversalFilterInputStream#in
*/
public void close() throws IOException {
in.close();
if(con != null) {
con.close();
}
}
/**
* Marks the current position in this input stream. A subsequent
* call to the <code>reset</code> method repositions this stream at
* the last marked position so that subsequent reads re-read the same bytes.
* <p>
* The <code>readlimit</code> argument tells this input stream to
* allow that many bytes to be read before the mark position gets
* invalidated.
* <p>
* This method simply performs <code>in.mark(readlimit)</code>.
*
* @param readlimit the maximum limit of bytes that can be read before
* the mark position becomes invalid.
* @see javax.microedition.io.UniversalFilterInputStream#in
* @see javax.microedition.io.UniversalFilterInputStream#reset()
*/
public synchronized void mark(int readlimit) {
marked = false; /* If the caller is marking then we cannot */
in.mark(readlimit);
}
/**
* Repositions this stream to the position at the time the
* <code>mark</code> method was last called on this input stream.
* <p>
* This method
* simply performs <code>in.reset()</code>.
* <p>
* Stream marks are intended to be used in
* situations where you need to read ahead a little to see what's in
* the stream. Often this is most easily done by invoking some
* general parser. If the stream is of the type handled by the
* parse, it just chugs along happily. If the stream is not of
* that type, the parser should toss an exception when it fails.
* If this happens within readlimit bytes, it allows the outer
* code to reset the stream and try another parser.
*
* @exception IOException if the stream has not been marked or if the
* mark has been invalidated.
* @see javax.microedition.io.UniversalFilterInputStream#in
* @see javax.microedition.io.UniversalFilterInputStream#mark(int)
*/
public synchronized void reset() throws IOException {
in.reset();
}
/**
* Tests if this input stream supports the <code>mark</code>
* and <code>reset</code> methods.
* This method
* simply performs <code>in.markSupported()</code>.
*
* @return <code>true</code> if this stream type supports the
* <code>mark</code> and <code>reset</code> method;
* <code>false</code> otherwise.
* @see javax.microedition.io.UniversalFilterInputStream#in
* @see java.io.InputStream#mark(int)
* @see java.io.InputStream#reset()
*/
public boolean markSupported() {
return in.markSupported();
}
/**
* Seek to a position in the stream
*
* @param pos the offset in bytes from the start of the data
*/
public void seek(long pos) throws IOException, IllegalAccessException {
if(marked) {
in.reset();
in.skip((int)pos);
} else {
throw new IllegalAccessException();
}
}
}