Back to index...

	/*
	* Copyright (c) 1994, 2013, 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.nio.channels.FileChannel;
	import sun.nio.ch.FileChannelImpl;


	/**
	* A <code>FileInputStream</code> obtains input bytes
	* from a file in a file system. What files
	* are available depends on the host environment.
	*
	* <p><code>FileInputStream</code> is meant for reading streams of raw bytes
	* such as image data. For reading streams of characters, consider using
	* <code>FileReader</code>.
	*
	* @author Arthur van Hoff
	* @see java.io.File
	* @see java.io.FileDescriptor
	* @see java.io.FileOutputStream
	* @see java.nio.file.Files#newInputStream
	* @since JDK1.0
	*/
	public
	class FileInputStream extends InputStream
	{
	/* File Descriptor - handle to the open file */
	private final FileDescriptor fd;

	/**
	* The path of the referenced file
	* (null if the stream is created with a file descriptor)
	*/
	private final String path;

	private FileChannel channel = null;

	private final Object closeLock = new Object();
	private volatile boolean closed = false;

	/**
	* Creates a <code>FileInputStream</code> by
	* opening a connection to an actual file,
	* the file named by the path name <code>name</code>
	* in the file system. A new <code>FileDescriptor</code>
	* object is created to represent this file
	* connection.
	* <p>
	* First, if there is a security
	* manager, its <code>checkRead</code> method
	* is called with the <code>name</code> argument
	* as its argument.
	* <p>
	* If the named file does not exist, is a directory rather than a regular
	* file, or for some other reason cannot be opened for reading then a
	* <code>FileNotFoundException</code> is thrown.
	*
	* @param name the system-dependent file name.
	* @exception FileNotFoundException if the file does not exist,
	* is a directory rather than a regular file,
	* or for some other reason cannot be opened for
	* reading.
	* @exception SecurityException if a security manager exists and its
	* <code>checkRead</code> method denies read access
	* to the file.
	* @see java.lang.SecurityManager#checkRead(java.lang.String)
	*/
	public FileInputStream(String name) throws FileNotFoundException {
	this(name != null ? new File(name) : null);
	}

	/**
	* Creates a <code>FileInputStream</code> by
	* opening a connection to an actual file,
	* the file named by the <code>File</code>
	* object <code>file</code> in the file system.
	* A new <code>FileDescriptor</code> object
	* is created to represent this file connection.
	* <p>
	* First, if there is a security manager,
	* its <code>checkRead</code> method is called
	* with the path represented by the <code>file</code>
	* argument as its argument.
	* <p>
	* If the named file does not exist, is a directory rather than a regular
	* file, or for some other reason cannot be opened for reading then a
	* <code>FileNotFoundException</code> is thrown.
	*
	* @param file the file to be opened for reading.
	* @exception FileNotFoundException if the file does not exist,
	* is a directory rather than a regular file,
	* or for some other reason cannot be opened for
	* reading.
	* @exception SecurityException if a security manager exists and its
	* <code>checkRead</code> method denies read access to the file.
	* @see java.io.File#getPath()
	* @see java.lang.SecurityManager#checkRead(java.lang.String)
	*/
	public FileInputStream(File file) throws FileNotFoundException {
	String name = (file != null ? file.getPath() : null);
	SecurityManager security = System.getSecurityManager();
	if (security != null) {
	security.checkRead(name);
	}
	if (name == null) {
	throw new NullPointerException();
	}
	if (file.isInvalid()) {
	throw new FileNotFoundException("Invalid file path");
	}
	fd = new FileDescriptor();
	fd.attach(this);
	path = name;
	open(name);
	}

	/**
	* Creates a <code>FileInputStream</code> by using the file descriptor
	* <code>fdObj</code>, which represents an existing connection to an
	* actual file in the file system.
	* <p>
	* If there is a security manager, its <code>checkRead</code> method is
	* called with the file descriptor <code>fdObj</code> as its argument to
	* see if it's ok to read the file descriptor. If read access is denied
	* to the file descriptor a <code>SecurityException</code> is thrown.
	* <p>
	* If <code>fdObj</code> is null then a <code>NullPointerException</code>
	* is thrown.
	* <p>
	* This constructor does not throw an exception if <code>fdObj</code>
	* is {@link java.io.FileDescriptor#valid() invalid}.
	* However, if the methods are invoked on the resulting stream to attempt
	* I/O on the stream, an <code>IOException</code> is thrown.
	*
	* @param fdObj the file descriptor to be opened for reading.
	* @throws SecurityException if a security manager exists and its
	* <code>checkRead</code> method denies read access to the
	* file descriptor.
	* @see SecurityManager#checkRead(java.io.FileDescriptor)
	*/
	public FileInputStream(FileDescriptor fdObj) {
	SecurityManager security = System.getSecurityManager();
	if (fdObj == null) {
	throw new NullPointerException();
	}
	if (security != null) {
	security.checkRead(fdObj);
	}
	fd = fdObj;
	path = null;

	/*
	* FileDescriptor is being shared by streams.
	* Register this stream with FileDescriptor tracker.
	*/
	fd.attach(this);
	}

	/**
	* Opens the specified file for reading.
	* @param name the name of the file
	*/
	private native void open0(String name) throws FileNotFoundException;

	// wrap native call to allow instrumentation
	/**
	* Opens the specified file for reading.
	* @param name the name of the file
	*/
	private void open(String name) throws FileNotFoundException {
	open0(name);
	}

	/**
	* Reads a byte of data from this input stream. This method blocks
	* if no input is yet available.
	*
	* @return the next byte of data, or <code>-1</code> if the end of the
	* file is reached.
	* @exception IOException if an I/O error occurs.
	*/
	public int read() throws IOException {
	return read0();
	}

	private native int read0() throws IOException;

	/**
	* Reads a subarray as a sequence of bytes.
	* @param b the data to be written
	* @param off the start offset in the data
	* @param len the number of bytes that are written
	* @exception IOException If an I/O error has occurred.
	*/
	private native int readBytes(byte b[], int off, int len) throws IOException;

	/**
	* Reads up to <code>b.length</code> bytes of data from this input
	* stream into an array of bytes. This method blocks until some input
	* is available.
	*
	* @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 file has been reached.
	* @exception IOException if an I/O error occurs.
	*/
	public int read(byte b[]) throws IOException {
	return readBytes(b, 0, b.length);
	}

	/**
	* Reads up to <code>len</code> bytes of data from this input stream
	* into an array of bytes. If <code>len</code> is not zero, the method
	* blocks until some input is available; otherwise, no
	* bytes are read and <code>0</code> is returned.
	*
	* @param b the buffer into which the data is read.
	* @param off the start offset in the destination array <code>b</code>
	* @param len the maximum number of bytes 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 file has been reached.
	* @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>
	* @exception IOException if an I/O error occurs.
	*/
	public int read(byte b[], int off, int len) throws IOException {
	return readBytes(b, off, len);
	}

	/**
	* Skips over and discards <code>n</code> bytes of data from the
	* input stream.
	*
	* <p>The <code>skip</code> method may, for a variety of
	* reasons, end up skipping over some smaller number of bytes,
	* possibly <code>0</code>. If <code>n</code> is negative, the method
	* will try to skip backwards. In case the backing file does not support
	* backward skip at its current position, an <code>IOException</code> is
	* thrown. The actual number of bytes skipped is returned. If it skips
	* forwards, it returns a positive value. If it skips backwards, it
	* returns a negative value.
	*
	* <p>This method may skip more bytes than what are remaining in the
	* backing file. This produces no exception and the number of bytes skipped
	* may include some number of bytes that were beyond the EOF of the
	* backing file. Attempting to read from the stream after skipping past
	* the end will result in -1 indicating the end of the file.
	*
	* @param n the number of bytes to be skipped.
	* @return the actual number of bytes skipped.
	* @exception IOException if n is negative, if the stream does not
	* support seek, or if an I/O error occurs.
	*/
	public long skip(long n) throws IOException {
	return skip0(n);
	}

	private native long skip0(long n) throws IOException;

	/**
	* Returns an estimate of the number of remaining 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. Returns 0 when the file
	* position is beyond EOF. 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> In some cases, a non-blocking read (or skip) may appear to be
	* blocked when it is merely slow, for example when reading large
	* files over slow networks.
	*
	* @return an estimate of the number of remaining bytes that can be read
	* (or skipped over) from this input stream without blocking.
	* @exception IOException if this file input stream has been closed by calling
	* {@code close} or an I/O error occurs.
	*/
	public int available() throws IOException {
	return available0();
	}

	private native int available0() throws IOException;

	/**
	* Closes this file input stream and releases any system resources
	* associated with the stream.
	*
	* <p> If this stream has an associated channel then the channel is closed
	* as well.
	*
	* @exception IOException if an I/O error occurs.
	*
	* @revised 1.4
	* @spec JSR-51
	*/
	public void close() throws IOException {
	synchronized (closeLock) {
	if (closed) {
	return;
	}
	closed = true;
	}
	if (channel != null) {
	channel.close();
	}

	fd.closeAll(new Closeable() {
	public void close() throws IOException {
	close0();
	}
	});
	}

	/**
	* Returns the <code>FileDescriptor</code>
	* object that represents the connection to
	* the actual file in the file system being
	* used by this <code>FileInputStream</code>.
	*
	* @return the file descriptor object associated with this stream.
	* @exception IOException if an I/O error occurs.
	* @see java.io.FileDescriptor
	*/
	public final FileDescriptor getFD() throws IOException {
	if (fd != null) {
	return fd;
	}
	throw new IOException();
	}

	/**
	* Returns the unique {@link java.nio.channels.FileChannel FileChannel}
	* object associated with this file input stream.
	*
	* <p> The initial {@link java.nio.channels.FileChannel#position()
	* position} of the returned channel will be equal to the
	* number of bytes read from the file so far. Reading bytes from this
	* stream will increment the channel's position. Changing the channel's
	* position, either explicitly or by reading, will change this stream's
	* file position.
	*
	* @return the file channel associated with this file input stream
	*
	* @since 1.4
	* @spec JSR-51
	*/
	public FileChannel getChannel() {
	synchronized (this) {
	if (channel == null) {
	channel = FileChannelImpl.open(fd, path, true, false, this);
	}
	return channel;
	}
	}

	private static native void initIDs();

	private native void close0() throws IOException;

	static {
	initIDs();
	}

	/**
	* Ensures that the <code>close</code> method of this file input stream is
	* called when there are no more references to it.
	*
	* @exception IOException if an I/O error occurs.
	* @see java.io.FileInputStream#close()
	*/
	protected void finalize() throws IOException {
	if ((fd != null) && (fd != FileDescriptor.in)) {
	/* if fd is shared, the references in FileDescriptor
	* will ensure that finalizer is only called when
	* safe to do so. All references using the fd have
	* become unreachable. We can call close()
	*/
	close();
	}
	}
	}

Back to index...