--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/java/io/InputStream.java Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,370 @@
+/*
+ * Copyright 1994-2006 Sun Microsystems, Inc. All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code 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. Sun designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Sun in the LICENSE file that accompanied this code.
+ *
+ * This code 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 in the LICENSE file that
+ * accompanied this code).
+ *
+ * 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 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+package java.io;
+
+/**
+ * This abstract class is the superclass of all classes representing
+ * an input stream of bytes.
+ *
+ * <p> Applications that need to define a subclass of <code>InputStream</code>
+ * must always provide a method that returns the next byte of input.
+ *
+ * @author Arthur van Hoff
+ * @see java.io.BufferedInputStream
+ * @see java.io.ByteArrayInputStream
+ * @see java.io.DataInputStream
+ * @see java.io.FilterInputStream
+ * @see java.io.InputStream#read()
+ * @see java.io.OutputStream
+ * @see java.io.PushbackInputStream
+ * @since JDK1.0
+ */
+public abstract class InputStream implements Closeable {
+
+ // SKIP_BUFFER_SIZE is used to determine the size of skipBuffer
+ private static final int SKIP_BUFFER_SIZE = 2048;
+ // skipBuffer is initialized in skip(long), if needed.
+ private static byte[] skipBuffer;
+
+ /**
+ * Reads the next byte of data from the 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> A subclass must provide an implementation of this method.
+ *
+ * @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.
+ */
+ public abstract int read() throws IOException;
+
+ /**
+ * Reads some number of bytes from the input stream and stores them into
+ * the buffer array <code>b</code>. The number of bytes actually read is
+ * returned as an integer. This method blocks until input data is
+ * available, end of file is detected, or an exception is thrown.
+ *
+ * <p> If the length of <code>b</code> is zero, then no bytes are read and
+ * <code>0</code> is returned; otherwise, there is an attempt to read at
+ * least one byte. If no byte is available because the stream is at the
+ * end of the file, the value <code>-1</code> is returned; otherwise, at
+ * least one byte is read and stored into <code>b</code>.
+ *
+ * <p> The first byte read is stored into element <code>b[0]</code>, the
+ * next one into <code>b[1]</code>, and so on. The number of bytes read is,
+ * at most, equal to the length of <code>b</code>. Let <i>k</i> be the
+ * number of bytes actually read; these bytes will be stored in elements
+ * <code>b[0]</code> through <code>b[</code><i>k</i><code>-1]</code>,
+ * leaving elements <code>b[</code><i>k</i><code>]</code> through
+ * <code>b[b.length-1]</code> unaffected.
+ *
+ * <p> The <code>read(b)</code> method for class <code>InputStream</code>
+ * has the same effect as: <pre><code> read(b, 0, b.length) </code></pre>
+ *
+ * @param b the buffer into which the data is read.
+ * @return the total number of bytes read into the buffer, or
+ * <code>-1</code> is there is no more data because the end of
+ * the stream has been reached.
+ * @exception IOException If the first byte cannot be read for any reason
+ * other than the end of the file, if the input stream has been closed, or
+ * if some other I/O error occurs.
+ * @exception NullPointerException if <code>b</code> is <code>null</code>.
+ * @see java.io.InputStream#read(byte[], int, int)
+ */
+ public int read(byte b[]) throws IOException {
+ return read(b, 0, b.length);
+ }
+
+ /**
+ * Reads up to <code>len</code> bytes of data from the input stream into
+ * an array of bytes. An attempt is made to read as many as
+ * <code>len</code> bytes, but a smaller number may be read.
+ * The number of bytes actually read is returned as an integer.
+ *
+ * <p> This method blocks until input data is available, end of file is
+ * detected, or an exception is thrown.
+ *
+ * <p> If <code>len</code> is zero, then no bytes are read and
+ * <code>0</code> is returned; otherwise, there is an attempt to read at
+ * least one byte. If no byte is available because the stream is at end of
+ * file, the value <code>-1</code> is returned; otherwise, at least one
+ * byte is read and stored into <code>b</code>.
+ *
+ * <p> The first byte read is stored into element <code>b[off]</code>, the
+ * next one into <code>b[off+1]</code>, and so on. The number of bytes read
+ * is, at most, equal to <code>len</code>. Let <i>k</i> be the number of
+ * bytes actually read; these bytes will be stored in elements
+ * <code>b[off]</code> through <code>b[off+</code><i>k</i><code>-1]</code>,
+ * leaving elements <code>b[off+</code><i>k</i><code>]</code> through
+ * <code>b[off+len-1]</code> unaffected.
+ *
+ * <p> In every case, elements <code>b[0]</code> through
+ * <code>b[off]</code> and elements <code>b[off+len]</code> through
+ * <code>b[b.length-1]</code> are unaffected.
+ *
+ * <p> The <code>read(b,</code> <code>off,</code> <code>len)</code> method
+ * for class <code>InputStream</code> simply calls the method
+ * <code>read()</code> repeatedly. If the first such call results in an
+ * <code>IOException</code>, that exception is returned from the call to
+ * the <code>read(b,</code> <code>off,</code> <code>len)</code> method. If
+ * any subsequent call to <code>read()</code> results in a
+ * <code>IOException</code>, the exception is caught and treated as if it
+ * were end of file; the bytes read up to that point are stored into
+ * <code>b</code> and the number of bytes read before the exception
+ * occurred is returned. The default implementation of this method blocks
+ * until the requested amount of input data <code>len</code> has been read,
+ * end of file is detected, or an exception is thrown. Subclasses are encouraged
+ * to provide a more efficient implementation of this method.
+ *
+ * @param b the buffer into which the data is read.
+ * @param off the start offset in array <code>b</code>
+ * at which the data is written.
+ * @param len the maximum number of bytes to 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 the first byte cannot be read for any reason
+ * other than end of file, or if the input stream has been closed, or if
+ * some other I/O error occurs.
+ * @exception NullPointerException If <code>b</code> is <code>null</code>.
+ * @exception IndexOutOfBoundsException If <code>off</code> is negative,
+ * <code>len</code> is negative, or <code>len</code> is greater than
+ * <code>b.length - off</code>
+ * @see java.io.InputStream#read()
+ */
+ public int read(byte b[], int off, int len) throws IOException {
+ if (b == null) {
+ throw new NullPointerException();
+ } else if (off < 0 || len < 0 || len > b.length - off) {
+ throw new IndexOutOfBoundsException();
+ } else if (len == 0) {
+ return 0;
+ }
+
+ int c = read();
+ if (c == -1) {
+ return -1;
+ }
+ b[off] = (byte)c;
+
+ int i = 1;
+ try {
+ for (; i < len ; i++) {
+ c = read();
+ if (c == -1) {
+ break;
+ }
+ b[off + i] = (byte)c;
+ }
+ } catch (IOException ee) {
+ }
+ return i;
+ }
+
+ /**
+ * Skips over and discards <code>n</code> bytes of data from this 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>.
+ * This may result from any of a number of conditions; reaching end of file
+ * before <code>n</code> bytes have been skipped is only one possibility.
+ * The actual number of bytes skipped is returned. If <code>n</code> is
+ * negative, no bytes are skipped.
+ *
+ * <p> The <code>skip</code> method of this class creates a
+ * byte array and then repeatedly reads into it until <code>n</code> bytes
+ * have been read or the end of the stream has been reached. Subclasses are
+ * encouraged to provide a more efficient implementation of this method.
+ * For instance, the implementation may depend on the ability to seek.
+ *
+ * @param n the number of bytes to be skipped.
+ * @return the actual number of bytes skipped.
+ * @exception IOException if the stream does not support seek,
+ * or if some other I/O error occurs.
+ */
+ public long skip(long n) throws IOException {
+
+ long remaining = n;
+ int nr;
+ if (skipBuffer == null)
+ skipBuffer = new byte[SKIP_BUFFER_SIZE];
+
+ byte[] localSkipBuffer = skipBuffer;
+
+ if (n <= 0) {
+ return 0;
+ }
+
+ while (remaining > 0) {
+ nr = read(localSkipBuffer, 0,
+ (int) Math.min(SKIP_BUFFER_SIZE, remaining));
+ if (nr < 0) {
+ break;
+ }
+ remaining -= nr;
+ }
+
+ return n - remaining;
+ }
+
+ /**
+ * 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> Note that while some implementations of {@code InputStream} will return
+ * the total number of bytes in the stream, many will not. It is
+ * never correct to use the return value of this method to allocate
+ * a buffer intended to hold all data in this stream.
+ *
+ * <p> A subclass' implementation of this method may choose to throw an
+ * {@link IOException} if this input stream has been closed by
+ * invoking the {@link #close()} method.
+ *
+ * <p> The {@code available} method for class {@code InputStream} always
+ * returns {@code 0}.
+ *
+ * <p> This method should be overridden by subclasses.
+ *
+ * @return an estimate of the number of bytes that can be read (or skipped
+ * over) from this input stream without blocking or {@code 0} when
+ * it reaches the end of the input stream.
+ * @exception IOException if an I/O error occurs.
+ */
+ public int available() throws IOException {
+ return 0;
+ }
+
+ /**
+ * Closes this input stream and releases any system resources associated
+ * with the stream.
+ *
+ * <p> The <code>close</code> method of <code>InputStream</code> does
+ * nothing.
+ *
+ * @exception IOException if an I/O error occurs.
+ */
+ public void close() throws IOException {}
+
+ /**
+ * 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> arguments tells this input stream to
+ * allow that many bytes to be read before the mark position gets
+ * invalidated.
+ *
+ * <p> The general contract of <code>mark</code> is that, if the method
+ * <code>markSupported</code> returns <code>true</code>, the stream somehow
+ * remembers all the bytes read after the call to <code>mark</code> and
+ * stands ready to supply those same bytes again if and whenever the method
+ * <code>reset</code> is called. However, the stream is not required to
+ * remember any data at all if more than <code>readlimit</code> bytes are
+ * read from the stream before <code>reset</code> is called.
+ *
+ * <p> Marking a closed stream should not have any effect on the stream.
+ *
+ * <p> The <code>mark</code> method of <code>InputStream</code> does
+ * nothing.
+ *
+ * @param readlimit the maximum limit of bytes that can be read before
+ * the mark position becomes invalid.
+ * @see java.io.InputStream#reset()
+ */
+ public synchronized void mark(int readlimit) {}
+
+ /**
+ * Repositions this stream to the position at the time the
+ * <code>mark</code> method was last called on this input stream.
+ *
+ * <p> The general contract of <code>reset</code> is:
+ *
+ * <p><ul>
+ *
+ * <li> If the method <code>markSupported</code> returns
+ * <code>true</code>, then:
+ *
+ * <ul><li> If the method <code>mark</code> has not been called since
+ * the stream was created, or the number of bytes read from the stream
+ * since <code>mark</code> was last called is larger than the argument
+ * to <code>mark</code> at that last call, then an
+ * <code>IOException</code> might be thrown.
+ *
+ * <li> If such an <code>IOException</code> is not thrown, then the
+ * stream is reset to a state such that all the bytes read since the
+ * most recent call to <code>mark</code> (or since the start of the
+ * file, if <code>mark</code> has not been called) will be resupplied
+ * to subsequent callers of the <code>read</code> method, followed by
+ * any bytes that otherwise would have been the next input data as of
+ * the time of the call to <code>reset</code>. </ul>
+ *
+ * <li> If the method <code>markSupported</code> returns
+ * <code>false</code>, then:
+ *
+ * <ul><li> The call to <code>reset</code> may throw an
+ * <code>IOException</code>.
+ *
+ * <li> If an <code>IOException</code> is not thrown, then the stream
+ * is reset to a fixed state that depends on the particular type of the
+ * input stream and how it was created. The bytes that will be supplied
+ * to subsequent callers of the <code>read</code> method depend on the
+ * particular type of the input stream. </ul></ul>
+ *
+ * <p>The method <code>reset</code> for class <code>InputStream</code>
+ * does nothing except throw an <code>IOException</code>.
+ *
+ * @exception IOException if this stream has not been marked or if the
+ * mark has been invalidated.
+ * @see java.io.InputStream#mark(int)
+ * @see java.io.IOException
+ */
+ public synchronized void reset() throws IOException {
+ throw new IOException("mark/reset not supported");
+ }
+
+ /**
+ * Tests if this input stream supports the <code>mark</code> and
+ * <code>reset</code> methods. Whether or not <code>mark</code> and
+ * <code>reset</code> are supported is an invariant property of a
+ * particular input stream instance. The <code>markSupported</code> method
+ * of <code>InputStream</code> returns <code>false</code>.
+ *
+ * @return <code>true</code> if this stream instance supports the mark
+ * and reset methods; <code>false</code> otherwise.
+ * @see java.io.InputStream#mark(int)
+ * @see java.io.InputStream#reset()
+ */
+ public boolean markSupported() {
+ return false;
+ }
+
+}