- /*
- * @(#)FileInputStream.java 1.60 03/01/23
- *
- * Copyright 2003 Sun Microsystems, Inc. All rights reserved.
- * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
- */
-
- 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
- * @version 1.60, 01/23/03
- * @see java.io.File
- * @see java.io.FileDescriptor
- * @see java.io.FileOutputStream
- * @since JDK1.0
- */
- public
- class FileInputStream extends InputStream
- {
- /* File Descriptor - handle to the open file */
- private FileDescriptor fd;
-
- private FileChannel channel = null;
-
- /**
- * 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();
- }
- fd = new FileDescriptor();
- 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.
- *
- * @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;
- }
-
- /**
- * Opens the specified file for reading.
- * @param name the name of the file
- */
- private native void open(String name) throws FileNotFoundException;
-
- /**
- * 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 native int read() 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. This method blocks until some input is
- * available.
- *
- * @param b the buffer into which the data is read.
- * @param off the start offset of the data.
- * @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 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. The <code>skip</code> method may, for a variety of
- * reasons, end up skipping over some smaller number of bytes,
- * possibly <code>0</code>. The actual number of bytes skipped is returned.
- *
- * @param n the number of bytes to be skipped.
- * @return the actual number of bytes skipped.
- * @exception IOException if an I/O error occurs.
- */
- public native long skip(long n) throws IOException;
-
- /**
- * Returns the number of bytes that can be read from this file input
- * stream without blocking.
- *
- * @return the number of bytes that can be read from this file input
- * stream without blocking.
- * @exception IOException if an I/O error occurs.
- */
- public native int available() 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 {
- if (channel != null)
- channel.close();
- 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()
- * </code>position<code>} 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, 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) {
- if (fd != fd.in) {
- close();
- }
- }
- }
- }