File or to a FileDescriptor. Whether or not
* a file is available or may be created depends upon the underlying
* platform. Some platforms, in particular, allow a file to be opened
* for writing by only one FileOutputStream (or other
* file-writing object) at a time. In such situations the constructors in
* this class will fail if the file involved is already open.
*
* FileOutputStream is meant for writing streams of raw bytes
* such as image data. For writing streams of characters, consider using
* FileWriter.
*
* @author Arthur van Hoff
* @version 1.57, 12/19/03
* @see java.io.File
* @see java.io.FileDescriptor
* @see java.io.FileInputStream
* @since JDK1.0
*/
public
class FileOutputStream extends OutputStream
{
/**
* The system dependent file descriptor. The value is
* 1 more than actual file descriptor. This means that
* the default value 0 indicates that the file is not open.
*/
private FileDescriptor fd;
private FileChannel channel= null;
private boolean append = false;
/**
* Creates an output file stream to write to the file with the
* specified name. A new FileDescriptor object is
* created to represent this file connection.
*
* First, if there is a security manager, its checkWrite
* method is called with name as its argument.
*
* If the file exists but is a directory rather than a regular file, does
* not exist but cannot be created, or cannot be opened for any other
* reason then a FileNotFoundException is thrown.
*
* @param name the system-dependent filename
* @exception FileNotFoundException if the file exists but is a directory
* rather than a regular file, does not exist but cannot
* be created, or cannot be opened for any other reason
* @exception SecurityException if a security manager exists and its
* checkWrite method denies write access
* to the file.
* @see java.lang.SecurityManager#checkWrite(java.lang.String)
*/
public FileOutputStream(String name) throws FileNotFoundException {
this(name != null ? new File(name) : null, false);
}
/**
* Creates an output file stream to write to the file with the specified
* name. If the second argument is true, then
* bytes will be written to the end of the file rather than the beginning.
* A new FileDescriptor object is created to represent this
* file connection.
*
* First, if there is a security manager, its checkWrite
* method is called with name as its argument.
*
* If the file exists but is a directory rather than a regular file, does
* not exist but cannot be created, or cannot be opened for any other
* reason then a FileNotFoundException is thrown.
*
* @param name the system-dependent file name
* @param append if true, then bytes will be written
* to the end of the file rather than the beginning
* @exception FileNotFoundException if the file exists but is a directory
* rather than a regular file, does not exist but cannot
* be created, or cannot be opened for any other reason.
* @exception SecurityException if a security manager exists and its
* checkWrite method denies write access
* to the file.
* @see java.lang.SecurityManager#checkWrite(java.lang.String)
* @since JDK1.1
*/
public FileOutputStream(String name, boolean append)
throws FileNotFoundException
{
this(name != null ? new File(name) : null, append);
}
/**
* Creates a file output stream to write to the file represented by
* the specified File object. A new
* FileDescriptor object is created to represent this
* file connection.
*
* First, if there is a security manager, its checkWrite
* method is called with the path represented by the file
* argument as its argument.
*
* If the file exists but is a directory rather than a regular file, does
* not exist but cannot be created, or cannot be opened for any other
* reason then a FileNotFoundException is thrown.
*
* @param file the file to be opened for writing.
* @exception FileNotFoundException if the file exists but is a directory
* rather than a regular file, does not exist but cannot
* be created, or cannot be opened for any other reason
* @exception SecurityException if a security manager exists and its
* checkWrite method denies write access
* to the file.
* @see java.io.File#getPath()
* @see java.lang.SecurityException
* @see java.lang.SecurityManager#checkWrite(java.lang.String)
*/
public FileOutputStream(File file) throws FileNotFoundException {
this(file, false);
}
/**
* Creates a file output stream to write to the file represented by
* the specified File object. If the second argument is
* true, then bytes will be written to the end of the file
* rather than the beginning. A new FileDescriptor object is
* created to represent this file connection.
*
* First, if there is a security manager, its checkWrite
* method is called with the path represented by the file
* argument as its argument.
*
* If the file exists but is a directory rather than a regular file, does
* not exist but cannot be created, or cannot be opened for any other
* reason then a FileNotFoundException is thrown.
*
* @param file the file to be opened for writing.
* @param append if true, then bytes will be written
* to the end of the file rather than the beginning
* @exception FileNotFoundException if the file exists but is a directory
* rather than a regular file, does not exist but cannot
* be created, or cannot be opened for any other reason
* @exception SecurityException if a security manager exists and its
* checkWrite method denies write access
* to the file.
* @see java.io.File#getPath()
* @see java.lang.SecurityException
* @see java.lang.SecurityManager#checkWrite(java.lang.String)
* @since 1.4
*/
public FileOutputStream(File file, boolean append)
throws FileNotFoundException
{
String name = (file != null ? file.getPath() : null);
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkWrite(name);
}
if (name == null) {
throw new NullPointerException();
}
fd = new FileDescriptor();
this.append = append;
if (append) {
openAppend(name);
} else {
open(name);
}
}
/**
* Creates an output file stream to write to the specified file
* descriptor, which represents an existing connection to an actual
* file in the file system.
*
* First, if there is a security manager, its checkWrite
* method is called with the file descriptor fdObj
* argument as its argument.
*
* @param fdObj the file descriptor to be opened for writing
* @exception SecurityException if a security manager exists and its
* checkWrite method denies
* write access to the file descriptor
* @see java.lang.SecurityManager#checkWrite(java.io.FileDescriptor)
*/
public FileOutputStream(FileDescriptor fdObj) {
SecurityManager security = System.getSecurityManager();
if (fdObj == null) {
throw new NullPointerException();
}
if (security != null) {
security.checkWrite(fdObj);
}
fd = fdObj;
}
/**
* Opens a file, with the specified name, for writing.
* @param name name of file to be opened
*/
private native void open(String name) throws FileNotFoundException;
/**
* Opens a file, with the specified name, for appending.
* @param name name of file to be opened
*/
private native void openAppend(String name) throws FileNotFoundException;
/**
* Writes the specified byte to this file output stream. Implements
* the write method of OutputStream.
*
* @param b the byte to be written.
* @exception IOException if an I/O error occurs.
*/
public native void write(int b) throws IOException;
/**
* Writes a sub array 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 void writeBytes(byte b[], int off, int len) throws IOException;
/**
* Writes b.length bytes from the specified byte array
* to this file output stream.
*
* @param b the data.
* @exception IOException if an I/O error occurs.
*/
public void write(byte b[]) throws IOException {
writeBytes(b, 0, b.length);
}
/**
* Writes len bytes from the specified byte array
* starting at offset off to this file output stream.
*
* @param b the data.
* @param off the start offset in the data.
* @param len the number of bytes to write.
* @exception IOException if an I/O error occurs.
*/
public void write(byte b[], int off, int len) throws IOException {
writeBytes(b, off, len);
}
/**
* Closes this file output stream and releases any system resources
* associated with this stream. This file output stream may no longer
* be used for writing bytes.
*
*
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 file descriptor associated with this stream.
*
* @return the FileDescriptor object that represents
* the connection to the file in the file system being used
* by this FileOutputStream object.
*
* @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 output stream.
The initial {@link java.nio.channels.FileChannel#position()
* position} of the returned channel will be equal to the
* number of bytes written to the file so far unless this stream is in
* append mode, in which case it will be equal to the size of the file.
* Writing bytes to this stream will increment the channel's position
* accordingly. Changing the channel's position, either explicitly or by
* writing, will change this stream's file position.
*
* @return the file channel associated with this file output stream
*
* @since 1.4
* @spec JSR-51
*/
public FileChannel getChannel() {
synchronized (this) {
if (channel == null)
channel = FileChannelImpl.open(fd, false, true, this, append);
return channel;
}
}
/**
* Cleans up the connection to the file, and ensures that the
* close method of this file output stream is
* called when there are no more references to this stream.
*
* @exception IOException if an I/O error occurs.
* @see java.io.FileInputStream#close()
*/
protected void finalize() throws IOException {
if (fd != null) {
if (fd == fd.out || fd == fd.err) {
flush();
} else {
close();
}
}
}
private native void close0() throws IOException;
private static native void initIDs();
static {
initIDs();
}
}