FileOutputStreampublic class FileOutputStream extends OutputStream A file output stream is an output stream for writing data to a
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.
|
| Fields Summary |
|---|
| private FileDescriptor | fdThe 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 FileChannel | channel | | private boolean | append |
| Constructors Summary |
|---|
public FileOutputStream(String name)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.
this(name != null ? new File(name) : null, false);
| public FileOutputStream(String name, boolean append)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.
this(name != null ? new File(name) : null, append);
| public FileOutputStream(File file)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.
this(file, false);
| public FileOutputStream(File file, boolean append)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.
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);
}
| public FileOutputStream(FileDescriptor fdObj)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.
SecurityManager security = System.getSecurityManager();
if (fdObj == null) {
throw new NullPointerException();
}
if (security != null) {
security.checkWrite(fdObj);
}
fd = fdObj;
|
| Methods Summary |
|---|
| public void | close()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.
if (channel != null)
channel.close();
close0();
| | private native void | close0()
| | protected void | finalize()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.
if (fd != null) {
if (fd == fd.out || fd == fd.err) {
flush();
} else {
close();
}
}
| | public java.nio.channels.FileChannel | getChannel()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.
synchronized (this) {
if (channel == null)
channel = FileChannelImpl.open(fd, false, true, this, append);
return channel;
}
| | public final java.io.FileDescriptor | getFD()Returns the file descriptor associated with this stream.
if (fd != null) return fd;
throw new IOException();
| | private static native void | initIDs()
| | private native void | open(java.lang.String name)Opens a file, with the specified name, for writing.
| | private native void | openAppend(java.lang.String name)Opens a file, with the specified name, for appending.
| | public void | write(byte[] b)Writes b.length bytes from the specified byte array
to this file output stream.
writeBytes(b, 0, b.length);
| | public void | write(byte[] b, int off, int len)Writes len bytes from the specified byte array
starting at offset off to this file output stream.
writeBytes(b, off, len);
| | public native void | write(int b)Writes the specified byte to this file output stream. Implements
the write method of OutputStream.
| | private native void | writeBytes(byte[] b, int off, int len)Writes a sub array as a sequence of bytes.
|
|
