/*
* @(#)FilterInputStream.java 1.12 95/08/13 Jonathan Payne
*
* 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;
/**
* Abstract class representing a filtered input stream of bytes.
* This class is the basis for enhancing input stream functionality.
* It allows multiple input stream filters to be chained together,
* each providing additional functionality.
* @version 1.12, 13 Aug 1995
* @author Jonathan Payne
*/
public
class FilterInputStream extends InputStream {
/**
* The actual input stream.
*/
protected InputStream in;
/**
* Creates an input stream filter.
* @param in the input stream
*/
protected FilterInputStream(InputStream in) {
this.in = in;
}
/**
* Reads a byte. Will block if no input is available.
* @return the byte read, or -1 if the end of the
* stream is reached.
* @exception IOException If an I/O error has occurred.
*/
public int read() throws IOException {
return in.read();
}
/**
* Reads into an array of bytes.
* Blocks until some input is available.
* @param b the buffer into which the data is read
* @return the actual number of bytes read, -1 is
* returned when the end of the stream is reached.
* @exception IOException If an I/O error has occurred.
*/
public int read(byte b[]) throws IOException {
return read(b, 0, b.length);
}
/**
* Reads into an array of bytes.
* Blocks until some input is available.
* This method should be overridden in a subclass for
* efficiency (the default implementation reads 1 byte
* at a time).
* @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 actual number of bytes read, -1 is
* returned when the end of the stream is reached.
* @exception IOException If an I/O error has occurred.
*/
public int read(byte b[], int off, int len) throws IOException {
return in.read(b, off, len);
}
/**
* Skips bytes of input.
* @param n bytes to be skipped
* @return actual number of bytes skipped
* @exception IOException If an I/O error has occurred.
*/
public long skip(long n) throws IOException {
return in.skip(n);
}
/**
* Returns the number of bytes that can be read.
* without blocking.
* @return the number of available bytes
*/
public int available() throws IOException {
return in.available();
}
/**
* Closes the input stream. 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 {
in.close();
}
/**
* Marks the current position in the input stream. A subsequent
* call to reset() will reposition the stream at the last
* marked position so that subsequent reads will re-read
* the same bytes. The stream promises to allow readlimit bytes
* to be read before the mark position gets invalidated.
* @param readlimit the maximum limit of bytes allowed tobe read before the
* mark position becomes invalid.
*/
public synchronized void mark(int readlimit) {
in.mark(readlimit);
}
/**
* Repositions the stream to the last marked position. If the
* stream has not been marked, or if the mark has been invalidated,
* an IOException is thrown. 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,
* which, if it happens within readlimit bytes, allows the outer
* code to reset the stream and try another parser.
*/
public synchronized void reset() throws IOException {
in.reset();
}
/**
* Returns true if this stream type supports mark/reset
*/
public boolean markSupported() {
return in.markSupported();
}
}