jtulach@146: /* jtulach@146: * Copyright (c) 1994, 2010, Oracle and/or its affiliates. All rights reserved. jtulach@146: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. jtulach@146: * jtulach@146: * This code is free software; you can redistribute it and/or modify it jtulach@146: * under the terms of the GNU General Public License version 2 only, as jtulach@146: * published by the Free Software Foundation. Oracle designates this jtulach@146: * particular file as subject to the "Classpath" exception as provided jtulach@146: * by Oracle in the LICENSE file that accompanied this code. jtulach@146: * jtulach@146: * This code is distributed in the hope that it will be useful, but WITHOUT jtulach@146: * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or jtulach@146: * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License jtulach@146: * version 2 for more details (a copy is included in the LICENSE file that jtulach@146: * accompanied this code). jtulach@146: * jtulach@146: * You should have received a copy of the GNU General Public License version jtulach@146: * 2 along with this work; if not, write to the Free Software Foundation, jtulach@146: * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. jtulach@146: * jtulach@146: * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA jtulach@146: * or visit www.oracle.com if you need additional information or have any jtulach@146: * questions. jtulach@146: */ jtulach@146: jtulach@146: package java.io; jtulach@146: jtulach@146: /** jtulach@146: * A FilterInputStream contains jtulach@146: * some other input stream, which it uses as jtulach@146: * its basic source of data, possibly transforming jtulach@146: * the data along the way or providing additional jtulach@146: * functionality. The class FilterInputStream jtulach@146: * itself simply overrides all methods of jtulach@146: * InputStream with versions that jtulach@146: * pass all requests to the contained input jtulach@146: * stream. Subclasses of FilterInputStream jtulach@146: * may further override some of these methods jtulach@146: * and may also provide additional methods jtulach@146: * and fields. jtulach@146: * jtulach@146: * @author Jonathan Payne jtulach@146: * @since JDK1.0 jtulach@146: */ jtulach@146: public jtulach@146: class FilterInputStream extends InputStream { jtulach@146: /** jtulach@146: * The input stream to be filtered. jtulach@146: */ jtulach@146: protected volatile InputStream in; jtulach@146: jtulach@146: /** jtulach@146: * Creates a FilterInputStream jtulach@146: * by assigning the argument in jtulach@146: * to the field this.in so as jtulach@146: * to remember it for later use. jtulach@146: * jtulach@146: * @param in the underlying input stream, or null if jtulach@146: * this instance is to be created without an underlying stream. jtulach@146: */ jtulach@146: protected FilterInputStream(InputStream in) { jtulach@146: this.in = in; jtulach@146: } jtulach@146: jtulach@146: /** jtulach@146: * Reads the next byte of data from this input stream. The value jtulach@146: * byte is returned as an int in the range jtulach@146: * 0 to 255. If no byte is available jtulach@146: * because the end of the stream has been reached, the value jtulach@146: * -1 is returned. This method blocks until input data jtulach@146: * is available, the end of the stream is detected, or an exception jtulach@146: * is thrown. jtulach@146: *

jtulach@146: * This method jtulach@146: * simply performs in.read() and returns the result. jtulach@146: * jtulach@146: * @return the next byte of data, or -1 if the end of the jtulach@146: * stream is reached. jtulach@146: * @exception IOException if an I/O error occurs. jtulach@146: * @see java.io.FilterInputStream#in jtulach@146: */ jtulach@146: public int read() throws IOException { jtulach@146: return in.read(); jtulach@146: } jtulach@146: jtulach@146: /** jtulach@146: * Reads up to byte.length bytes of data from this jtulach@146: * input stream into an array of bytes. This method blocks until some jtulach@146: * input is available. jtulach@146: *

jtulach@146: * This method simply performs the call jtulach@146: * read(b, 0, b.length) and returns jtulach@146: * the result. It is important that it does jtulach@146: * not do in.read(b) instead; jtulach@146: * certain subclasses of FilterInputStream jtulach@146: * depend on the implementation strategy actually jtulach@146: * used. jtulach@146: * jtulach@146: * @param b the buffer into which the data is read. jtulach@146: * @return the total number of bytes read into the buffer, or jtulach@146: * -1 if there is no more data because the end of jtulach@146: * the stream has been reached. jtulach@146: * @exception IOException if an I/O error occurs. jtulach@146: * @see java.io.FilterInputStream#read(byte[], int, int) jtulach@146: */ jtulach@146: public int read(byte b[]) throws IOException { jtulach@146: return read(b, 0, b.length); jtulach@146: } jtulach@146: jtulach@146: /** jtulach@146: * Reads up to len bytes of data from this input stream jtulach@146: * into an array of bytes. If len is not zero, the method jtulach@146: * blocks until some input is available; otherwise, no jtulach@146: * bytes are read and 0 is returned. jtulach@146: *

jtulach@146: * This method simply performs in.read(b, off, len) jtulach@146: * and returns the result. jtulach@146: * jtulach@146: * @param b the buffer into which the data is read. jtulach@146: * @param off the start offset in the destination array b jtulach@146: * @param len the maximum number of bytes read. jtulach@146: * @return the total number of bytes read into the buffer, or jtulach@146: * -1 if there is no more data because the end of jtulach@146: * the stream has been reached. jtulach@146: * @exception NullPointerException If b is null. jtulach@146: * @exception IndexOutOfBoundsException If off is negative, jtulach@146: * len is negative, or len is greater than jtulach@146: * b.length - off jtulach@146: * @exception IOException if an I/O error occurs. jtulach@146: * @see java.io.FilterInputStream#in jtulach@146: */ jtulach@146: public int read(byte b[], int off, int len) throws IOException { jtulach@146: return in.read(b, off, len); jtulach@146: } jtulach@146: jtulach@146: /** jtulach@146: * Skips over and discards n bytes of data from the jtulach@146: * input stream. The skip method may, for a variety of jtulach@146: * reasons, end up skipping over some smaller number of bytes, jtulach@146: * possibly 0. The actual number of bytes skipped is jtulach@146: * returned. jtulach@146: *

jtulach@146: * This method simply performs in.skip(n). jtulach@146: * jtulach@146: * @param n the number of bytes to be skipped. jtulach@146: * @return the actual number of bytes skipped. jtulach@146: * @exception IOException if the stream does not support seek, jtulach@146: * or if some other I/O error occurs. jtulach@146: */ jtulach@146: public long skip(long n) throws IOException { jtulach@146: return in.skip(n); jtulach@146: } jtulach@146: jtulach@146: /** jtulach@146: * Returns an estimate of the number of bytes that can be read (or jtulach@146: * skipped over) from this input stream without blocking by the next jtulach@146: * caller of a method for this input stream. The next caller might be jtulach@146: * the same thread or another thread. A single read or skip of this jtulach@146: * many bytes will not block, but may read or skip fewer bytes. jtulach@146: *

jtulach@146: * This method returns the result of {@link #in in}.available(). jtulach@146: * jtulach@146: * @return an estimate of the number of bytes that can be read (or skipped jtulach@146: * over) from this input stream without blocking. jtulach@146: * @exception IOException if an I/O error occurs. jtulach@146: */ jtulach@146: public int available() throws IOException { jtulach@146: return in.available(); jtulach@146: } jtulach@146: jtulach@146: /** jtulach@146: * Closes this input stream and releases any system resources jtulach@146: * associated with the stream. jtulach@146: * This jtulach@146: * method simply performs in.close(). jtulach@146: * jtulach@146: * @exception IOException if an I/O error occurs. jtulach@146: * @see java.io.FilterInputStream#in jtulach@146: */ jtulach@146: public void close() throws IOException { jtulach@146: in.close(); jtulach@146: } jtulach@146: jtulach@146: /** jtulach@146: * Marks the current position in this input stream. A subsequent jtulach@146: * call to the reset method repositions this stream at jtulach@146: * the last marked position so that subsequent reads re-read the same bytes. jtulach@146: *

jtulach@146: * The readlimit argument tells this input stream to jtulach@146: * allow that many bytes to be read before the mark position gets jtulach@146: * invalidated. jtulach@146: *

jtulach@146: * This method simply performs in.mark(readlimit). jtulach@146: * jtulach@146: * @param readlimit the maximum limit of bytes that can be read before jtulach@146: * the mark position becomes invalid. jtulach@146: * @see java.io.FilterInputStream#in jtulach@146: * @see java.io.FilterInputStream#reset() jtulach@146: */ jtulach@146: public synchronized void mark(int readlimit) { jtulach@146: in.mark(readlimit); jtulach@146: } jtulach@146: jtulach@146: /** jtulach@146: * Repositions this stream to the position at the time the jtulach@146: * mark method was last called on this input stream. jtulach@146: *

jtulach@146: * This method jtulach@146: * simply performs in.reset(). jtulach@146: *

jtulach@146: * Stream marks are intended to be used in jtulach@146: * situations where you need to read ahead a little to see what's in jtulach@146: * the stream. Often this is most easily done by invoking some jtulach@146: * general parser. If the stream is of the type handled by the jtulach@146: * parse, it just chugs along happily. If the stream is not of jtulach@146: * that type, the parser should toss an exception when it fails. jtulach@146: * If this happens within readlimit bytes, it allows the outer jtulach@146: * code to reset the stream and try another parser. jtulach@146: * jtulach@146: * @exception IOException if the stream has not been marked or if the jtulach@146: * mark has been invalidated. jtulach@146: * @see java.io.FilterInputStream#in jtulach@146: * @see java.io.FilterInputStream#mark(int) jtulach@146: */ jtulach@146: public synchronized void reset() throws IOException { jtulach@146: in.reset(); jtulach@146: } jtulach@146: jtulach@146: /** jtulach@146: * Tests if this input stream supports the mark jtulach@146: * and reset methods. jtulach@146: * This method jtulach@146: * simply performs in.markSupported(). jtulach@146: * jtulach@146: * @return true if this stream type supports the jtulach@146: * mark and reset method; jtulach@146: * false otherwise. jtulach@146: * @see java.io.FilterInputStream#in jtulach@146: * @see java.io.InputStream#mark(int) jtulach@146: * @see java.io.InputStream#reset() jtulach@146: */ jtulach@146: public boolean markSupported() { jtulach@146: return in.markSupported(); jtulach@146: } jtulach@146: }