/*
* @(#)FileInputStream.java 1.60 06/10/10
*
* Copyright 1990-2008 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
*
* This program 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.
*
* This program 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 at /legal/license.txt).
*
* 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 or visit www.sun.com if you need additional
* information or have any questions.
*
*/
package java.io;
/**
* 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>.
*
* @version 1.45, 02/02/00
* @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;
/**
* 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 {
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
*/
/* Comment out due to no NIO in CDC
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();
}
}
}
}