author | bpb |
Wed, 17 Jul 2019 14:24:37 -0700 | |
changeset 55728 | 978350939943 |
parent 47216 | 71c04702a3d5 |
child 55741 | 880266b6e5b3 |
permissions | -rw-r--r-- |
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/* |
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* Copyright (c) 1994, 2019, Oracle and/or its affiliates. All rights reserved. |
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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* |
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* This code is free software; you can redistribute it and/or modify it |
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* under the terms of the GNU General Public License version 2 only, as |
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* published by the Free Software Foundation. Oracle designates this |
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* particular file as subject to the "Classpath" exception as provided |
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* by Oracle in the LICENSE file that accompanied this code. |
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* |
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* This code is distributed in the hope that it will be useful, but WITHOUT |
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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* version 2 for more details (a copy is included in the LICENSE file that |
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* accompanied this code). |
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* |
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* You should have received a copy of the GNU General Public License version |
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* 2 along with this work; if not, write to the Free Software Foundation, |
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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* |
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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* or visit www.oracle.com if you need additional information or have any |
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* questions. |
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*/ |
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package java.io; |
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/** |
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* A <code>FilterInputStream</code> contains |
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* some other input stream, which it uses as |
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* its basic source of data, possibly transforming |
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* the data along the way or providing additional |
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* functionality. The class <code>FilterInputStream</code> |
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* itself simply overrides all methods of |
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* <code>InputStream</code> with versions that |
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* pass all requests to the contained input |
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* stream. Subclasses of <code>FilterInputStream</code> |
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* may further override some of these methods |
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* and may also provide additional methods |
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* and fields. |
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* |
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* @author Jonathan Payne |
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* @since 1.0 |
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*/ |
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public |
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class FilterInputStream extends InputStream { |
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/** |
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* The input stream to be filtered. |
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*/ |
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protected volatile InputStream in; |
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/** |
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* Creates a <code>FilterInputStream</code> |
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* by assigning the argument <code>in</code> |
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* to the field <code>this.in</code> so as |
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* to remember it for later use. |
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* |
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* @param in the underlying input stream, or <code>null</code> if |
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* this instance is to be created without an underlying stream. |
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*/ |
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protected FilterInputStream(InputStream in) { |
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if (in == null) { |
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throw new NullPointerException(); |
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} |
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this.in = in; |
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} |
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/** |
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* Reads the next byte of data from this input stream. The value |
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* byte is returned as an <code>int</code> in the range |
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* <code>0</code> to <code>255</code>. If no byte is available |
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* because the end of the stream has been reached, the value |
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* <code>-1</code> is returned. This method blocks until input data |
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* is available, the end of the stream is detected, or an exception |
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* is thrown. |
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* <p> |
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* This method |
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* simply performs <code>in.read()</code> and returns the result. |
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* |
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* @return the next byte of data, or <code>-1</code> if the end of the |
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* stream is reached. |
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* @exception IOException if an I/O error occurs. |
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* @see java.io.FilterInputStream#in |
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*/ |
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public int read() throws IOException { |
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return in.read(); |
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} |
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/** |
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* Reads up to <code>b.length</code> bytes of data from this |
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* input stream into an array of bytes. This method blocks until some |
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* input is available. |
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* <p> |
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* This method simply performs the call |
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* <code>read(b, 0, b.length)</code> and returns |
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* the result. It is important that it does |
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* <i>not</i> do <code>in.read(b)</code> instead; |
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* certain subclasses of <code>FilterInputStream</code> |
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* depend on the implementation strategy actually |
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* used. |
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* |
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* @param b the buffer into which the data is read. |
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* @return the total number of bytes read into the buffer, or |
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* <code>-1</code> if there is no more data because the end of |
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* the stream has been reached. |
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* @exception IOException if an I/O error occurs. |
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* @see java.io.FilterInputStream#read(byte[], int, int) |
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*/ |
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public int read(byte b[]) throws IOException { |
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return read(b, 0, b.length); |
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} |
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/** |
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* Reads up to <code>len</code> bytes of data from this input stream |
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* into an array of bytes. If <code>len</code> is not zero, the method |
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* blocks until some input is available; otherwise, no |
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* bytes are read and <code>0</code> is returned. |
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* <p> |
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* This method simply performs <code>in.read(b, off, len)</code> |
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* and returns the result. |
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* |
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* @param b the buffer into which the data is read. |
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* @param off the start offset in the destination array <code>b</code> |
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* @param len the maximum number of bytes read. |
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* @return the total number of bytes read into the buffer, or |
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* <code>-1</code> if there is no more data because the end of |
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* the stream has been reached. |
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* @exception NullPointerException If <code>b</code> is <code>null</code>. |
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* @exception IndexOutOfBoundsException If <code>off</code> is negative, |
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* <code>len</code> is negative, or <code>len</code> is greater than |
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* <code>b.length - off</code> |
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* @exception IOException if an I/O error occurs. |
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* @see java.io.FilterInputStream#in |
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*/ |
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public int read(byte b[], int off, int len) throws IOException { |
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return in.read(b, off, len); |
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} |
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/** |
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* Skips over and discards <code>n</code> bytes of data from the |
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* input stream. The <code>skip</code> method may, for a variety of |
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* reasons, end up skipping over some smaller number of bytes, |
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* possibly <code>0</code>. The actual number of bytes skipped is |
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* returned. |
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* <p> |
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* This method simply performs <code>in.skip(n)</code>. |
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* |
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* @param n the number of bytes to be skipped. |
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* @return the actual number of bytes skipped. |
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* @throws IOException if {@code in.skip(n)} throws an IOException. |
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*/ |
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public long skip(long n) throws IOException { |
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return in.skip(n); |
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} |
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/** |
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* Returns an estimate of the number of bytes that can be read (or |
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* skipped over) from this input stream without blocking by the next |
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* caller of a method for this input stream. The next caller might be |
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* the same thread or another thread. A single read or skip of this |
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* many bytes will not block, but may read or skip fewer bytes. |
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* <p> |
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* This method returns the result of {@link #in in}.available(). |
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* |
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* @return an estimate of the number of bytes that can be read (or skipped |
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* over) from this input stream without blocking. |
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* @exception IOException if an I/O error occurs. |
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*/ |
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public int available() throws IOException { |
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return in.available(); |
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} |
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/** |
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* Closes this input stream and releases any system resources |
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* associated with the stream. |
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* This |
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* method simply performs <code>in.close()</code>. |
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* |
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* @exception IOException if an I/O error occurs. |
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* @see java.io.FilterInputStream#in |
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*/ |
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public void close() throws IOException { |
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in.close(); |
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} |
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/** |
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* Marks the current position in this input stream. A subsequent |
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* call to the <code>reset</code> method repositions this stream at |
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* the last marked position so that subsequent reads re-read the same bytes. |
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* <p> |
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* The <code>readlimit</code> argument tells this input stream to |
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* allow that many bytes to be read before the mark position gets |
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* invalidated. |
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* <p> |
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* This method simply performs <code>in.mark(readlimit)</code>. |
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* |
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* @param readlimit the maximum limit of bytes that can be read before |
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* the mark position becomes invalid. |
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* @see java.io.FilterInputStream#in |
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* @see java.io.FilterInputStream#reset() |
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*/ |
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public synchronized void mark(int readlimit) { |
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in.mark(readlimit); |
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} |
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/** |
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* Repositions this stream to the position at the time the |
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* <code>mark</code> method was last called on this input stream. |
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* <p> |
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* This method |
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* simply performs <code>in.reset()</code>. |
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* <p> |
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* Stream marks are intended to be used in |
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* situations where you need to read ahead a little to see what's in |
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* the stream. Often this is most easily done by invoking some |
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* general parser. If the stream is of the type handled by the |
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* parse, it just chugs along happily. If the stream is not of |
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* that type, the parser should toss an exception when it fails. |
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* If this happens within readlimit bytes, it allows the outer |
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* code to reset the stream and try another parser. |
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* |
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* @exception IOException if the stream has not been marked or if the |
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* mark has been invalidated. |
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* @see java.io.FilterInputStream#in |
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* @see java.io.FilterInputStream#mark(int) |
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*/ |
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public synchronized void reset() throws IOException { |
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in.reset(); |
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} |
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/** |
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* Tests if this input stream supports the <code>mark</code> |
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* and <code>reset</code> methods. |
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* This method |
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* simply performs <code>in.markSupported()</code>. |
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* |
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* @return <code>true</code> if this stream type supports the |
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* <code>mark</code> and <code>reset</code> method; |
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* <code>false</code> otherwise. |
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* @see java.io.FilterInputStream#in |
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* @see java.io.InputStream#mark(int) |
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* @see java.io.InputStream#reset() |
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*/ |
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public boolean markSupported() { |
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return in.markSupported(); |
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} |
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} |