FileDescriptor.
*
* @author Aaron M. Renn (arenn@urbanophile.com)
* @author Tom Tromey (tromey@cygnus.com)
*/
public class FileOutputStream extends OutputStream
{
private FileDescriptor fd;
private FileChannelImpl ch;
/**
* This method initializes a FileOutputStream object to write
* to the named file. The file is created if it does not exist, and
* the bytes written are written starting at the beginning of the file if
* the append argument is false or at the end
* of the file if the append argument is true.
*
* Before opening a file, a security check is performed by calling the
* checkWrite method of the SecurityManager (if
* one exists) with the name of the file to be opened. An exception is
* thrown if writing is not allowed.
*
* @param path The name of the file this stream should write to
* @param append true to append bytes to the end of the file,
* or false to write bytes to the beginning
*
* @exception SecurityException If write access to the file is not allowed
* @exception FileNotFoundException If a non-security error occurs
*/
public FileOutputStream (String path, boolean append)
throws SecurityException, FileNotFoundException
{
this (new File(path), append);
}
/**
* This method initializes a FileOutputStream object to write
* to the named file. The file is created if it does not exist, and
* the bytes written are written starting at the beginning of the file.
*
* Before opening a file, a security check is performed by calling the
* checkWrite method of the SecurityManager (if
* one exists) with the name of the file to be opened. An exception is
* thrown if writing is not allowed.
*
* @param path The name of the file this stream should write to
*
* @exception SecurityException If write access to the file is not allowed
* @exception FileNotFoundException If a non-security error occurs
*/
public FileOutputStream (String path)
throws SecurityException, FileNotFoundException
{
this (path, false);
}
/**
* This method initializes a FileOutputStream object to write
* to the specified File object. The file is created if it
* does not exist, and the bytes written are written starting at the
* beginning of the file.
*
* Before opening a file, a security check is performed by calling the
* checkWrite method of the SecurityManager (if
* one exists) with the name of the file to be opened. An exception is
* thrown if writing is not allowed.
*
* @param file The File object this stream should write to
*
* @exception SecurityException If write access to the file is not allowed
* @exception FileNotFoundException If a non-security error occurs
*/
public FileOutputStream (File file)
throws SecurityException, FileNotFoundException
{
this (file, false);
}
/**
* This method initializes a FileOutputStream object to write
* to the specified File object. The file is created if it
* does not exist, and the bytes written are written starting at the
* beginning of the file if the append parameter is
* false. Otherwise bytes are written at the end of the
* file.
*
* Before opening a file, a security check is performed by calling the
* checkWrite method of the SecurityManager (if
* one exists) with the name of the file to be opened. An exception is
* thrown if writing is not allowed.
*
* @param file The File object this stream should write to
* @param append true to append bytes to the end of the file,
* or false to write bytes to the beginning
*
* @exception SecurityException If write access to the file is not allowed
* @exception FileNotFoundException If a non-security error occurs
*/
public FileOutputStream (File file, boolean append)
throws FileNotFoundException
{
SecurityManager s = System.getSecurityManager();
if (s != null)
s.checkWrite(file.getPath());
ch = FileChannelImpl.create(file, (append
? FileChannelImpl.WRITE
| FileChannelImpl.APPEND
: FileChannelImpl.WRITE));
}
/**
* This method initializes a FileOutputStream object to write
* to the file represented by the specified FileDescriptor
* object. This method does not create any underlying disk file or
* reposition the file pointer of the given descriptor. It assumes that
* this descriptor is ready for writing as is.
*
* Before opening a file, a security check is performed by calling the
* checkWrite method of the SecurityManager (if
* one exists) with the specified FileDescriptor as an argument.
* An exception is thrown if writing is not allowed.
*
* @param fdObj The FileDescriptor this stream should write to
*
* @exception SecurityException If write access to the file is not allowed
*/
public FileOutputStream (FileDescriptor fdObj)
throws SecurityException
{
// Hmm, no other exception but this one to throw, but if the descriptor
// isn't valid, we surely don't have "permission" to write to it.
if (!fdObj.valid())
throw new SecurityException("Invalid FileDescriptor");
SecurityManager s = System.getSecurityManager();
if (s != null)
s.checkWrite(fdObj);
fd = fdObj;
ch = (FileChannelImpl) fdObj.channel;
}
FileOutputStream(FileChannelImpl ch)
{
this.ch = ch;
}
protected void finalize () throws IOException
{
// We don't actually need this, but we include it because it is
// mentioned in the JCL.
}
/**
* This method returns a FileDescriptor object representing
* the file that is currently being written to
*
* @return A FileDescriptor object for this stream
*
* @exception IOException If an error occurs
*/
public final FileDescriptor getFD () throws IOException
{
synchronized (this)
{
if (fd == null)
fd = new FileDescriptor (ch);
return fd;
}
}
/**
* This method writes a single byte of data to the file.
*
* @param b The byte of data to write, passed as an int
*
* @exception IOException If an error occurs
*/
public void write (int b) throws IOException
{
ch.write (b);
}
/**
* This method writes all the bytes in the specified array to the
* file.
*
* @param buf The array of bytes to write to the file
*
* @exception IOException If an error occurs
*/
public void write (byte[] buf)
throws IOException
{
write (buf, 0, buf.length);
}
/**
* This method writes len bytes from the byte array
* buf to the file starting at index offset.
*
* @param buf The array of bytes to write to the file
* @param offset The offset into the array to start writing bytes from
* @param len The number of bytes to write to the file
*
* @exception IOException If an error occurs
*/
public void write (byte[] buf, int offset, int len)
throws IOException
{
if (offset < 0
|| len < 0
|| offset + len > buf.length)
throw new ArrayIndexOutOfBoundsException ();
ch.write (buf, offset, len);
}
/**
* This method closes the underlying file. Any further attempts to
* write to this stream will likely generate an exception since the
* file is closed.
*
* @exception IOException If an error occurs
*/
public void close () throws IOException
{
ch.close();
}
/**
* This method creates a java.nio.channels.FileChannel.
* Nio does not allow one to create a file channel directly.
* A file channel must be created by first creating an instance of
* Input/Output/RandomAccessFile and invoking the getChannel() method on it.
*/
public synchronized FileChannel getChannel()
{
return ch;
}
} // class FileOutputStream