java.lang.Object | +--java.io.InputStream | +--java.io.FileInputStream
FileInputStream(java.lang.String name) This method initializes a |
FileInputStream(java.io.File file) This method initializes a |
FileInputStream(java.io.FileDescriptor fd) This method initializes a |
int | available() This method returns the number of bytes that can be read from this stream before a read can block. |
synchronized void | close() This method closes the stream. |
void | finalize() This method ensures that the underlying file is closed when this object is garbage collected. |
java.nio.channels.FileChannel | getChannel() |
java.io.FileDescriptor | getFD() This method returns a |
synchronized int | read() This method reads an unsigned byte from the input stream and returns it as an int in the range of 0-255. |
int | read(byte[] buf) This method reads bytes from a stream and stores them into a caller supplied buffer. |
synchronized int | read(byte[] buf, int offset, int len) This method read bytes from a stream and stores them into a caller supplied buffer. |
synchronized long | skip(long num_bytes) This method skips the specified number of bytes in the stream. |
public FileInputStream(java.io.File file)
FileInputStream
to read from the
specified File
object. A security check is first made to determine
whether or not access to this file is allowed. This is done by
calling the checkRead()
method of the SecurityManager
(if one exists) with the name of this file. An exception is thrown
if reading is not allowed. If the file does not exist, an exception
is also thrown.
file
- The File
object this stream should read fromSecurityException
- If read access to the file is not allowedFileNotFoundException
- If the file does not exist.public FileInputStream(java.io.FileDescriptor fd)
FileInputStream
to read from the
specified FileDescriptor
object. A security check is first made to
determine whether or not access to this file is allowed. This is done by
calling the checkRead()
method of the SecurityManager
(if one exists) with the specified FileDescriptor
An exception is
thrown if reading is not allowed.
fd
- The FileDescriptor
object this stream should read fromSecurityException
- If read access to the file is not allowedpublic FileInputStream(java.lang.String name)
FileInputStream
to read from the
specified named file. A security check is first made to determine
whether or not access to this file is allowed. This is done by
calling the checkRead()
method of the SecurityManager
(if one exists) with the name of this file. An exception is thrown
if reading is not allowed. If the file does not exist, an exception
is also thrown.
name
- The name of the file this stream should read fromSecurityException
- If read access to the file is not allowedFileNotFoundException
- If the file does not exist.public int available()
This method returns the number of unread bytes remaining in the file if the descriptor being read from is an actual file. If this method is reading from a ''special'' file such a the standard input, this method will return the appropriate value for the stream being read.
Be aware that reads on plain files that do not reside locally might possibly block even if this method says they should not. For example, a remote server might crash, preventing an NFS mounted file from being read.
IOException
- If an error occurspublic synchronized void close()
IOException
- If an error occurs.protected void finalize()
IOException
- If an error occurspublic FileChannel getChannel()
public final FileDescriptor getFD()
FileDescriptor
object representing the
underlying native file handle of the file this stream is reading
from
FileDescriptor
for this streamIOException
- If an error occurspublic synchronized int read()
This method will block until the byte can be read.
IOException
- If an error occurspublic int read(byte[] buf)
This method will block until some data can be read.
This method operates by calling an overloaded read method like so:
read(buf, 0, buf.length)
buf
- The buffer into which the bytes read will be stored.IOException
- If an error occurs.public synchronized int read(byte[] buf, int offset, int len)
offset
into
the buffer and attempts to read len
bytes. This method can
return before reading the number of bytes requested. The actual number
of bytes read is returned as an int. A -1 is returned to indicate the
end of the stream.
This method will block until some data can be read.
buf
- The array into which the bytes read should be storedoffset
- The offset into the array to start storing byteslen
- The requested number of bytes to readIOException
- If an error occurs.public synchronized long skip(long num_bytes)
This method reads and discards bytes into a 256 byte array until the specified number of bytes were skipped or until either the end of stream is reached or a read attempt returns a short count. Subclasses can override this metho to provide a more efficient implementation where one exists.
num_bytes
- The requested number of bytes to skipIOException
- If an error occurs