| /* |
| * Copyright (c) 1994, 2016, Oracle and/or its affiliates. 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. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package java.io; |
| |
| import java.util.Arrays; |
| import java.util.Objects; |
| |
| /** |
| * 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 1.0 |
| */ |
| public abstract class InputStream implements Closeable { |
| |
| // MAX_SKIP_BUFFER_SIZE is used to determine the maximum buffer size to |
| // use when skipping. |
| private static final int MAX_SKIP_BUFFER_SIZE = 2048; |
| |
| private static final int DEFAULT_BUFFER_SIZE = 8192; |
| |
| /** |
| * 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> 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 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; |
| } |
| |
| /** |
| * 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 final int MAX_BUFFER_SIZE = Integer.MAX_VALUE - 8; |
| |
| /** |
| * Reads all remaining bytes from the input stream. This method blocks until |
| * all remaining bytes have been read and end of stream is detected, or an |
| * exception is thrown. This method does not close the input stream. |
| * |
| * <p> When this stream reaches end of stream, further invocations of this |
| * method will return an empty byte array. |
| * |
| * <p> Note that this method is intended for simple cases where it is |
| * convenient to read all bytes into a byte array. It is not intended for |
| * reading input streams with large amounts of data. |
| * |
| * <p> The behavior for the case where the input stream is <i>asynchronously |
| * closed</i>, or the thread interrupted during the read, is highly input |
| * stream specific, and therefore not specified. |
| * |
| * <p> If an I/O error occurs reading from the input stream, then it may do |
| * so after some, but not all, bytes have been read. Consequently the input |
| * stream may not be at end of stream and may be in an inconsistent state. |
| * It is strongly recommended that the stream be promptly closed if an I/O |
| * error occurs. |
| * |
| * @return a byte array containing the bytes read from this input stream |
| * @throws IOException if an I/O error occurs |
| * @throws OutOfMemoryError if an array of the required size cannot be |
| * allocated. For example, if an array larger than {@code 2GB} would |
| * be required to store the bytes. |
| * |
| * @since 9 |
| */ |
| public byte[] readAllBytes() throws IOException { |
| byte[] buf = new byte[DEFAULT_BUFFER_SIZE]; |
| int capacity = buf.length; |
| int nread = 0; |
| int n; |
| for (;;) { |
| // read to EOF which may read more or less than initial buffer size |
| while ((n = read(buf, nread, capacity - nread)) > 0) |
| nread += n; |
| |
| // if the last call to read returned -1, then we're done |
| if (n < 0) |
| break; |
| |
| // need to allocate a larger buffer |
| if (capacity <= MAX_BUFFER_SIZE - capacity) { |
| capacity = capacity << 1; |
| } else { |
| if (capacity == MAX_BUFFER_SIZE) |
| throw new OutOfMemoryError("Required array size too large"); |
| capacity = MAX_BUFFER_SIZE; |
| } |
| buf = Arrays.copyOf(buf, capacity); |
| } |
| return (capacity == nread) ? buf : Arrays.copyOf(buf, nread); |
| } |
| |
| /** |
| * Reads the requested number of bytes from the input stream into the given |
| * byte array. This method blocks until {@code len} bytes of input data have |
| * been read, end of stream is detected, or an exception is thrown. The |
| * number of bytes actually read, possibly zero, is returned. This method |
| * does not close the input stream. |
| * |
| * <p> In the case where end of stream is reached before {@code len} bytes |
| * have been read, then the actual number of bytes read will be returned. |
| * When this stream reaches end of stream, further invocations of this |
| * method will return zero. |
| * |
| * <p> If {@code len} is zero, then no bytes are read and {@code 0} is |
| * returned; otherwise, there is an attempt to read up to {@code len} bytes. |
| * |
| * <p> The first byte read is stored into element {@code b[off]}, the next |
| * one in to {@code b[off+1]}, and so on. The number of bytes read is, at |
| * most, equal to {@code len}. Let <i>k</i> be the number of bytes actually |
| * read; these bytes will be stored in elements {@code b[off]} through |
| * {@code b[off+}<i>k</i>{@code -1]}, leaving elements {@code b[off+}<i>k</i> |
| * {@code ]} through {@code b[off+len-1]} unaffected. |
| * |
| * <p> The behavior for the case where the input stream is <i>asynchronously |
| * closed</i>, or the thread interrupted during the read, is highly input |
| * stream specific, and therefore not specified. |
| * |
| * <p> If an I/O error occurs reading from the input stream, then it may do |
| * so after some, but not all, bytes of {@code b} have been updated with |
| * data from the input stream. Consequently the input stream and {@code b} |
| * may be in an inconsistent state. It is strongly recommended that the |
| * stream be promptly closed if an I/O error occurs. |
| * |
| * @param b the byte array into which the data is read |
| * @param off the start offset in {@code b} at which the data is written |
| * @param len the maximum number of bytes to read |
| * @return the actual number of bytes read into the buffer |
| * @throws IOException if an I/O error occurs |
| * @throws NullPointerException if {@code b} is {@code null} |
| * @throws IndexOutOfBoundsException If {@code off} is negative, {@code len} |
| * is negative, or {@code len} is greater than {@code b.length - off} |
| * |
| * @since 9 |
| */ |
| public int readNBytes(byte[] b, int off, int len) throws IOException { |
| Objects.requireNonNull(b); |
| if (off < 0 || len < 0 || len > b.length - off) |
| throw new IndexOutOfBoundsException(); |
| int n = 0; |
| while (n < len) { |
| int count = read(b, off + n, len - n); |
| if (count < 0) |
| break; |
| n += count; |
| } |
| return n; |
| } |
| |
| /** |
| * 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} is |
| * negative, the {@code skip} method for class {@code InputStream} always |
| * returns 0, and no bytes are skipped. Subclasses may handle the negative |
| * value differently. |
| * |
| * <p> The <code>skip</code> method implementation 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. |
| * @throws IOException if an I/O error occurs. |
| */ |
| public long skip(long n) throws IOException { |
| |
| long remaining = n; |
| int nr; |
| |
| if (n <= 0) { |
| return 0; |
| } |
| |
| int size = (int)Math.min(MAX_SKIP_BUFFER_SIZE, remaining); |
| byte[] skipBuffer = new byte[size]; |
| while (remaining > 0) { |
| nr = read(skipBuffer, 0, (int)Math.min(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: |
| * |
| * <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; |
| } |
| |
| /** |
| * Reads all bytes from this input stream and writes the bytes to the |
| * given output stream in the order that they are read. On return, this |
| * input stream will be at end of stream. This method does not close either |
| * stream. |
| * <p> |
| * This method may block indefinitely reading from the input stream, or |
| * writing to the output stream. The behavior for the case where the input |
| * and/or output stream is <i>asynchronously closed</i>, or the thread |
| * interrupted during the transfer, is highly input and output stream |
| * specific, and therefore not specified. |
| * <p> |
| * If an I/O error occurs reading from the input stream or writing to the |
| * output stream, then it may do so after some bytes have been read or |
| * written. Consequently the input stream may not be at end of stream and |
| * one, or both, streams may be in an inconsistent state. It is strongly |
| * recommended that both streams be promptly closed if an I/O error occurs. |
| * |
| * @param out the output stream, non-null |
| * @return the number of bytes transferred |
| * @throws IOException if an I/O error occurs when reading or writing |
| * @throws NullPointerException if {@code out} is {@code null} |
| * |
| * @since 9 |
| */ |
| public long transferTo(OutputStream out) throws IOException { |
| Objects.requireNonNull(out, "out"); |
| long transferred = 0; |
| byte[] buffer = new byte[DEFAULT_BUFFER_SIZE]; |
| int read; |
| while ((read = this.read(buffer, 0, DEFAULT_BUFFER_SIZE)) >= 0) { |
| out.write(buffer, 0, read); |
| transferred += read; |
| } |
| return transferred; |
| } |
| } |