You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
490 lines
18 KiB
490 lines
18 KiB
/*
|
|
* Copyright (c) 1994, 2013, Oracle and/or its affiliates. All rights reserved.
|
|
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*
|
|
*/
|
|
|
|
package java.io;
|
|
import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
|
|
|
|
/**
|
|
* A <code>BufferedInputStream</code> adds
|
|
* functionality to another input stream-namely,
|
|
* the ability to buffer the input and to
|
|
* support the <code>mark</code> and <code>reset</code>
|
|
* methods. When the <code>BufferedInputStream</code>
|
|
* is created, an internal buffer array is
|
|
* created. As bytes from the stream are read
|
|
* or skipped, the internal buffer is refilled
|
|
* as necessary from the contained input stream,
|
|
* many bytes at a time. The <code>mark</code>
|
|
* operation remembers a point in the input
|
|
* stream and the <code>reset</code> operation
|
|
* causes all the bytes read since the most
|
|
* recent <code>mark</code> operation to be
|
|
* reread before new bytes are taken from
|
|
* the contained input stream.
|
|
*
|
|
* @author Arthur van Hoff
|
|
* @since JDK1.0
|
|
*/
|
|
public
|
|
class BufferedInputStream extends FilterInputStream {
|
|
|
|
private static int DEFAULT_BUFFER_SIZE = 8192;
|
|
|
|
/**
|
|
* The maximum size of array to allocate.
|
|
* Some VMs reserve some header words in an array.
|
|
* Attempts to allocate larger arrays may result in
|
|
* OutOfMemoryError: Requested array size exceeds VM limit
|
|
*/
|
|
private static int MAX_BUFFER_SIZE = Integer.MAX_VALUE - 8;
|
|
|
|
/**
|
|
* The internal buffer array where the data is stored. When necessary,
|
|
* it may be replaced by another array of
|
|
* a different size.
|
|
*/
|
|
protected volatile byte buf[];
|
|
|
|
/**
|
|
* Atomic updater to provide compareAndSet for buf. This is
|
|
* necessary because closes can be asynchronous. We use nullness
|
|
* of buf[] as primary indicator that this stream is closed. (The
|
|
* "in" field is also nulled out on close.)
|
|
*/
|
|
private static final
|
|
AtomicReferenceFieldUpdater<BufferedInputStream, byte[]> bufUpdater =
|
|
AtomicReferenceFieldUpdater.newUpdater
|
|
(BufferedInputStream.class, byte[].class, "buf");
|
|
|
|
/**
|
|
* The index one greater than the index of the last valid byte in
|
|
* the buffer.
|
|
* This value is always
|
|
* in the range <code>0</code> through <code>buf.length</code>;
|
|
* elements <code>buf[0]</code> through <code>buf[count-1]
|
|
* </code>contain buffered input data obtained
|
|
* from the underlying input stream.
|
|
*/
|
|
protected int count;
|
|
|
|
/**
|
|
* The current position in the buffer. This is the index of the next
|
|
* character to be read from the <code>buf</code> array.
|
|
* <p>
|
|
* This value is always in the range <code>0</code>
|
|
* through <code>count</code>. If it is less
|
|
* than <code>count</code>, then <code>buf[pos]</code>
|
|
* is the next byte to be supplied as input;
|
|
* if it is equal to <code>count</code>, then
|
|
* the next <code>read</code> or <code>skip</code>
|
|
* operation will require more bytes to be
|
|
* read from the contained input stream.
|
|
*
|
|
* @see java.io.BufferedInputStream#buf
|
|
*/
|
|
protected int pos;
|
|
|
|
/**
|
|
* The value of the <code>pos</code> field at the time the last
|
|
* <code>mark</code> method was called.
|
|
* <p>
|
|
* This value is always
|
|
* in the range <code>-1</code> through <code>pos</code>.
|
|
* If there is no marked position in the input
|
|
* stream, this field is <code>-1</code>. If
|
|
* there is a marked position in the input
|
|
* stream, then <code>buf[markpos]</code>
|
|
* is the first byte to be supplied as input
|
|
* after a <code>reset</code> operation. If
|
|
* <code>markpos</code> is not <code>-1</code>,
|
|
* then all bytes from positions <code>buf[markpos]</code>
|
|
* through <code>buf[pos-1]</code> must remain
|
|
* in the buffer array (though they may be
|
|
* moved to another place in the buffer array,
|
|
* with suitable adjustments to the values
|
|
* of <code>count</code>, <code>pos</code>,
|
|
* and <code>markpos</code>); they may not
|
|
* be discarded unless and until the difference
|
|
* between <code>pos</code> and <code>markpos</code>
|
|
* exceeds <code>marklimit</code>.
|
|
*
|
|
* @see java.io.BufferedInputStream#mark(int)
|
|
* @see java.io.BufferedInputStream#pos
|
|
*/
|
|
protected int markpos = -1;
|
|
|
|
/**
|
|
* The maximum read ahead allowed after a call to the
|
|
* <code>mark</code> method before subsequent calls to the
|
|
* <code>reset</code> method fail.
|
|
* Whenever the difference between <code>pos</code>
|
|
* and <code>markpos</code> exceeds <code>marklimit</code>,
|
|
* then the mark may be dropped by setting
|
|
* <code>markpos</code> to <code>-1</code>.
|
|
*
|
|
* @see java.io.BufferedInputStream#mark(int)
|
|
* @see java.io.BufferedInputStream#reset()
|
|
*/
|
|
protected int marklimit;
|
|
|
|
/**
|
|
* Check to make sure that underlying input stream has not been
|
|
* nulled out due to close; if not return it;
|
|
*/
|
|
private InputStream getInIfOpen() throws IOException {
|
|
InputStream input = in;
|
|
if (input == null)
|
|
throw new IOException("Stream closed");
|
|
return input;
|
|
}
|
|
|
|
/**
|
|
* Check to make sure that buffer has not been nulled out due to
|
|
* close; if not return it;
|
|
*/
|
|
private byte[] getBufIfOpen() throws IOException {
|
|
byte[] buffer = buf;
|
|
if (buffer == null)
|
|
throw new IOException("Stream closed");
|
|
return buffer;
|
|
}
|
|
|
|
/**
|
|
* Creates a <code>BufferedInputStream</code>
|
|
* and saves its argument, the input stream
|
|
* <code>in</code>, for later use. An internal
|
|
* buffer array is created and stored in <code>buf</code>.
|
|
*
|
|
* @param in the underlying input stream.
|
|
*/
|
|
public BufferedInputStream(InputStream in) {
|
|
this(in, DEFAULT_BUFFER_SIZE);
|
|
}
|
|
|
|
/**
|
|
* Creates a <code>BufferedInputStream</code>
|
|
* with the specified buffer size,
|
|
* and saves its argument, the input stream
|
|
* <code>in</code>, for later use. An internal
|
|
* buffer array of length <code>size</code>
|
|
* is created and stored in <code>buf</code>.
|
|
*
|
|
* @param in the underlying input stream.
|
|
* @param size the buffer size.
|
|
* @exception IllegalArgumentException if {@code size <= 0}.
|
|
*/
|
|
public BufferedInputStream(InputStream in, int size) {
|
|
super(in);
|
|
if (size <= 0) {
|
|
throw new IllegalArgumentException("Buffer size <= 0");
|
|
}
|
|
buf = new byte[size];
|
|
}
|
|
|
|
/**
|
|
* Fills the buffer with more data, taking into account
|
|
* shuffling and other tricks for dealing with marks.
|
|
* Assumes that it is being called by a synchronized method.
|
|
* This method also assumes that all data has already been read in,
|
|
* hence pos > count.
|
|
*/
|
|
private void fill() throws IOException {
|
|
byte[] buffer = getBufIfOpen();
|
|
if (markpos < 0)
|
|
pos = 0; /* no mark: throw away the buffer */
|
|
else if (pos >= buffer.length) /* no room left in buffer */
|
|
if (markpos > 0) { /* can throw away early part of the buffer */
|
|
int sz = pos - markpos;
|
|
System.arraycopy(buffer, markpos, buffer, 0, sz);
|
|
pos = sz;
|
|
markpos = 0;
|
|
} else if (buffer.length >= marklimit) {
|
|
markpos = -1; /* buffer got too big, invalidate mark */
|
|
pos = 0; /* drop buffer contents */
|
|
} else if (buffer.length >= MAX_BUFFER_SIZE) {
|
|
throw new OutOfMemoryError("Required array size too large");
|
|
} else { /* grow buffer */
|
|
int nsz = (pos <= MAX_BUFFER_SIZE - pos) ?
|
|
pos * 2 : MAX_BUFFER_SIZE;
|
|
if (nsz > marklimit)
|
|
nsz = marklimit;
|
|
byte nbuf[] = new byte[nsz];
|
|
System.arraycopy(buffer, 0, nbuf, 0, pos);
|
|
if (!bufUpdater.compareAndSet(this, buffer, nbuf)) {
|
|
// Can't replace buf if there was an async close.
|
|
// Note: This would need to be changed if fill()
|
|
// is ever made accessible to multiple threads.
|
|
// But for now, the only way CAS can fail is via close.
|
|
// assert buf == null;
|
|
throw new IOException("Stream closed");
|
|
}
|
|
buffer = nbuf;
|
|
}
|
|
count = pos;
|
|
int n = getInIfOpen().read(buffer, pos, buffer.length - pos);
|
|
if (n > 0)
|
|
count = n + pos;
|
|
}
|
|
|
|
/**
|
|
* See
|
|
* the general contract of the <code>read</code>
|
|
* method of <code>InputStream</code>.
|
|
*
|
|
* @return the next byte of data, or <code>-1</code> if the end of the
|
|
* stream is reached.
|
|
* @exception IOException if this input stream has been closed by
|
|
* invoking its {@link #close()} method,
|
|
* or an I/O error occurs.
|
|
* @see java.io.FilterInputStream#in
|
|
*/
|
|
public synchronized int read() throws IOException {
|
|
if (pos >= count) {
|
|
fill();
|
|
if (pos >= count)
|
|
return -1;
|
|
}
|
|
return getBufIfOpen()[pos++] & 0xff;
|
|
}
|
|
|
|
/**
|
|
* Read characters into a portion of an array, reading from the underlying
|
|
* stream at most once if necessary.
|
|
*/
|
|
private int read1(byte[] b, int off, int len) throws IOException {
|
|
int avail = count - pos;
|
|
if (avail <= 0) {
|
|
/* If the requested length is at least as large as the buffer, and
|
|
if there is no mark/reset activity, do not bother to copy the
|
|
bytes into the local buffer. In this way buffered streams will
|
|
cascade harmlessly. */
|
|
if (len >= getBufIfOpen().length && markpos < 0) {
|
|
return getInIfOpen().read(b, off, len);
|
|
}
|
|
fill();
|
|
avail = count - pos;
|
|
if (avail <= 0) return -1;
|
|
}
|
|
int cnt = (avail < len) ? avail : len;
|
|
System.arraycopy(getBufIfOpen(), pos, b, off, cnt);
|
|
pos += cnt;
|
|
return cnt;
|
|
}
|
|
|
|
/**
|
|
* Reads bytes from this byte-input stream into the specified byte array,
|
|
* starting at the given offset.
|
|
*
|
|
* <p> This method implements the general contract of the corresponding
|
|
* <code>{@link InputStream#read(byte[], int, int) read}</code> method of
|
|
* the <code>{@link InputStream}</code> class. As an additional
|
|
* convenience, it attempts to read as many bytes as possible by repeatedly
|
|
* invoking the <code>read</code> method of the underlying stream. This
|
|
* iterated <code>read</code> continues until one of the following
|
|
* conditions becomes true: <ul>
|
|
*
|
|
* <li> The specified number of bytes have been read,
|
|
*
|
|
* <li> The <code>read</code> method of the underlying stream returns
|
|
* <code>-1</code>, indicating end-of-file, or
|
|
*
|
|
* <li> The <code>available</code> method of the underlying stream
|
|
* returns zero, indicating that further input requests would block.
|
|
*
|
|
* </ul> If the first <code>read</code> on the underlying stream returns
|
|
* <code>-1</code> to indicate end-of-file then this method returns
|
|
* <code>-1</code>. Otherwise this method returns the number of bytes
|
|
* actually read.
|
|
*
|
|
* <p> Subclasses of this class are encouraged, but not required, to
|
|
* attempt to read as many bytes as possible in the same fashion.
|
|
*
|
|
* @param b destination buffer.
|
|
* @param off offset at which to start storing bytes.
|
|
* @param len maximum number of bytes to read.
|
|
* @return the number of bytes read, or <code>-1</code> if the end of
|
|
* the stream has been reached.
|
|
* @exception IOException if this input stream has been closed by
|
|
* invoking its {@link #close()} method,
|
|
* or an I/O error occurs.
|
|
*/
|
|
public synchronized int read(byte b[], int off, int len)
|
|
throws IOException
|
|
{
|
|
getBufIfOpen(); // Check for closed stream
|
|
if ((off | len | (off + len) | (b.length - (off + len))) < 0) {
|
|
throw new IndexOutOfBoundsException();
|
|
} else if (len == 0) {
|
|
return 0;
|
|
}
|
|
|
|
int n = 0;
|
|
for (;;) {
|
|
int nread = read1(b, off + n, len - n);
|
|
if (nread <= 0)
|
|
return (n == 0) ? nread : n;
|
|
n += nread;
|
|
if (n >= len)
|
|
return n;
|
|
// if not closed but no bytes available, return
|
|
InputStream input = in;
|
|
if (input != null && input.available() <= 0)
|
|
return n;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* See the general contract of the <code>skip</code>
|
|
* method of <code>InputStream</code>.
|
|
*
|
|
* @exception IOException if the stream does not support seek,
|
|
* or if this input stream has been closed by
|
|
* invoking its {@link #close()} method, or an
|
|
* I/O error occurs.
|
|
*/
|
|
public synchronized long skip(long n) throws IOException {
|
|
getBufIfOpen(); // Check for closed stream
|
|
if (n <= 0) {
|
|
return 0;
|
|
}
|
|
long avail = count - pos;
|
|
|
|
if (avail <= 0) {
|
|
// If no mark position set then don't keep in buffer
|
|
if (markpos <0)
|
|
return getInIfOpen().skip(n);
|
|
|
|
// Fill in buffer to save bytes for reset
|
|
fill();
|
|
avail = count - pos;
|
|
if (avail <= 0)
|
|
return 0;
|
|
}
|
|
|
|
long skipped = (avail < n) ? avail : n;
|
|
pos += skipped;
|
|
return skipped;
|
|
}
|
|
|
|
/**
|
|
* Returns an estimate of the number of bytes that can be read (or
|
|
* skipped over) from this input stream without blocking by the next
|
|
* invocation of a method for this 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 returns the sum of the number of bytes remaining to be read in
|
|
* the buffer (<code>count - pos</code>) and the result of calling the
|
|
* {@link java.io.FilterInputStream#in in}.available().
|
|
*
|
|
* @return an estimate of the number of bytes that can be read (or skipped
|
|
* over) from this input stream without blocking.
|
|
* @exception IOException if this input stream has been closed by
|
|
* invoking its {@link #close()} method,
|
|
* or an I/O error occurs.
|
|
*/
|
|
public synchronized int available() throws IOException {
|
|
int n = count - pos;
|
|
int avail = getInIfOpen().available();
|
|
return n > (Integer.MAX_VALUE - avail)
|
|
? Integer.MAX_VALUE
|
|
: n + avail;
|
|
}
|
|
|
|
/**
|
|
* See the general contract of the <code>mark</code>
|
|
* method of <code>InputStream</code>.
|
|
*
|
|
* @param readlimit the maximum limit of bytes that can be read before
|
|
* the mark position becomes invalid.
|
|
* @see java.io.BufferedInputStream#reset()
|
|
*/
|
|
public synchronized void mark(int readlimit) {
|
|
marklimit = readlimit;
|
|
markpos = pos;
|
|
}
|
|
|
|
/**
|
|
* See the general contract of the <code>reset</code>
|
|
* method of <code>InputStream</code>.
|
|
* <p>
|
|
* If <code>markpos</code> is <code>-1</code>
|
|
* (no mark has been set or the mark has been
|
|
* invalidated), an <code>IOException</code>
|
|
* is thrown. Otherwise, <code>pos</code> is
|
|
* set equal to <code>markpos</code>.
|
|
*
|
|
* @exception IOException if this stream has not been marked or,
|
|
* if the mark has been invalidated, or the stream
|
|
* has been closed by invoking its {@link #close()}
|
|
* method, or an I/O error occurs.
|
|
* @see java.io.BufferedInputStream#mark(int)
|
|
*/
|
|
public synchronized void reset() throws IOException {
|
|
getBufIfOpen(); // Cause exception if closed
|
|
if (markpos < 0)
|
|
throw new IOException("Resetting to invalid mark");
|
|
pos = markpos;
|
|
}
|
|
|
|
/**
|
|
* Tests if this input stream supports the <code>mark</code>
|
|
* and <code>reset</code> methods. The <code>markSupported</code>
|
|
* method of <code>BufferedInputStream</code> returns
|
|
* <code>true</code>.
|
|
*
|
|
* @return a <code>boolean</code> indicating if this stream type supports
|
|
* the <code>mark</code> and <code>reset</code> methods.
|
|
* @see java.io.InputStream#mark(int)
|
|
* @see java.io.InputStream#reset()
|
|
*/
|
|
public boolean markSupported() {
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* Closes this input stream and releases any system resources
|
|
* associated with the stream.
|
|
* Once the stream has been closed, further read(), available(), reset(),
|
|
* or skip() invocations will throw an IOException.
|
|
* Closing a previously closed stream has no effect.
|
|
*
|
|
* @exception IOException if an I/O error occurs.
|
|
*/
|
|
public void close() throws IOException {
|
|
byte[] buffer;
|
|
while ( (buffer = buf) != null) {
|
|
if (bufUpdater.compareAndSet(this, buffer, null)) {
|
|
InputStream input = in;
|
|
in = null;
|
|
if (input != null)
|
|
input.close();
|
|
return;
|
|
}
|
|
// Else retry in case a new buf was CASed in fill()
|
|
}
|
|
}
|
|
}
|