edu.sdsc.grid.io.local
Class LocalFileInputStream

java.lang.Object
  java.io.InputStream
      edu.sdsc.grid.io.GeneralFileInputStream
          edu.sdsc.grid.io.local.LocalFileInputStream

All Implemented Interfaces:

java.io.Closeable

public class LocalFileInputStream
extends GeneralFileInputStream

A LocalFileInputStream obtains input bytes from a file in a file system. What files are available depends on the host environment.

LocalFileInputStream is meant for reading streams of raw bytes such as image data.

The original intention for this class was to subclass java.io.FileInputStream. But that is not currently the case.

Since:

JARGON1.4

Field Summary

Fields inherited from class edu.sdsc.grid.io.GeneralFileInputStream

fd

Constructor Summary

LocalFileInputStream(LocalFile file)
Creates a LocalFileInputStream by opening a connection to an actual file, the file named by the LocalFile object file in the file system.

LocalFileInputStream(java.lang.String name)
Creates a LocalFileInputStream by opening a connection to an actual file, the file named by the path name name in the file system.

Method Summary

int	available() Returns the number of bytes that can be read from this file input stream without blocking.
void	close() Closes this file input stream and releases any system resources associated with the stream.
protected void	finalize() Ensures that the close method of this file input stream is called when there are no more references to it.
protected void	open(GeneralFile file) Opens the given file for use by this stream.
int	read() Reads a byte of data from this input stream.
int	read(byte[] b) Reads up to b.length bytes of data from this input stream into an array of bytes.
int	read(byte[] b, int off, int len) Reads up to len bytes of data from the input stream into an array of bytes.
long	skip(long n) Skips over and discards n bytes of data from the input stream.

Methods inherited from class java.io.InputStream

mark, markSupported, reset

Methods inherited from class java.lang.Object

clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

LocalFileInputStream

public LocalFileInputStream(java.lang.String name)
                     throws java.io.IOException

Creates a LocalFileInputStream by opening a connection to an actual file, the file named by the path name name in the file system.

First, the security is checked to verify the file can be read.

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 IOException is thrown.

Parameters:

name - the system-dependent file name.

Throws:

java.io.IOException - if the file does not exist, is a directory rather than a regular file, or for some other reason cannot be opened for reading.

LocalFileInputStream

public LocalFileInputStream(LocalFile file)
                     throws java.io.IOException

Creates a LocalFileInputStream by opening a connection to an actual file, the file named by the LocalFile object file in the file system. A new FileDescriptor object is created to represent this file connection.

First, the security is checked to verify the file can be read.

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 IOException is thrown.

Parameters:

file - the file to be opened for reading.

Throws:

java.io.IOException - if the file does not exist, is a directory rather than a regular file, or for some other reason cannot be opened for reading.

See Also:

File.getPath()

Method Detail

finalize

protected void finalize()
                 throws java.io.IOException

Ensures that the close method of this file input stream is called when there are no more references to it.

Overrides:

finalize in class GeneralFileInputStream

Throws:

java.io.IOException - if an I/O error occurs.

See Also:

edu.sdsc.grid.io.LocalFileInputStream#close()

open

protected void open(GeneralFile file)
             throws java.io.IOException

Opens the given file for use by this stream.

Specified by:

open in class GeneralFileInputStream

Parameters:

file - the file to be opened.

Throws:

java.io.IOException - if an I/O error occurs.

read

public int read()
         throws java.io.IOException

Reads a byte of data from this input stream. This method blocks if no input is yet available.

Specified by:

read in class GeneralFileInputStream

Returns:

the next byte of data, or -1 if the end of the file is reached.

Throws:

java.io.IOException - if an I/O error occurs.

read

public int read(byte[] b)
         throws java.io.IOException

Reads up to b.length bytes of data from this input stream into an array of bytes. This method blocks until some input is available.

Overrides:

read in class GeneralFileInputStream

Parameters:

b - the buffer into which the data is read.

Returns:

the total number of bytes read into the buffer, or -1 if there is no more data because the end of the file has been reached.

Throws:

java.io.IOException - if an I/O error occurs.

See Also:

InputStream.read(byte[], int, int)

read

public int read(byte[] b,
                int off,
                int len)
         throws java.io.IOException

Reads up to len bytes of data from the input stream into an array of bytes. An attempt is made to read as many as len bytes, but a smaller number may be read, possibly zero. The number of bytes actually read is returned as an integer.

This method blocks until input data is available, end of file is detected, or an exception is thrown.

If b is null, a NullPointerException is thrown.

If off is negative, or len is negative, or off+len is greater than the length of the array b, then an IndexOutOfBoundsException is thrown.

If len is zero, then no bytes are read and 0 is returned; otherwise, there is an attempt to read at least one byte. If no byte is available because the stream is at end of file, the value -1 is returned; otherwise, at least one byte is read and stored into b.

The first byte read is stored into element b[off], the next one into b[off+1], and so on. The number of bytes read is, at most, equal to len. Let k be the number of bytes actually read; these bytes will be stored in elements b[off] through b[off+k-1], leaving elements b[off+k] through b[off+len-1] unaffected.

In every case, elements b[0] through b[off] and elements b[off+len] through b[b.length-1] are unaffected.

If the first byte cannot be read for any reason other than end of file, then an IOException is thrown. In particular, an IOException is thrown if the input stream has been closed.

The read(b, off, len) method for class InputStream simply calls the method read() repeatedly. If the first such call results in an IOException, that exception is returned from the call to the read(b, off, len) method. If any subsequent call to read() results in a IOException, the exception is caught and treated as if it were end of file; the bytes read up to that point are stored into b and the number of bytes read before the exception occurred is returned. Subclasses are encouraged to provide a more efficient implementation of this method.

Specified by:

read in class GeneralFileInputStream

Parameters:

b - the buffer into which the data is read.

off - the start offset in array b at which the data is written.

len - the maximum number of bytes to read.

Returns:

the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.

Throws:

java.io.IOException - if an I/O error occurs.

java.lang.NullPointerException - if b is null.

See Also:

InputStream.read()

skip

public long skip(long n)
          throws java.io.IOException

Skips over and discards n bytes of data from the input stream. The skip method may, for a variety of reasons, end up skipping over some smaller number of bytes, possibly 0. The actual number of bytes skipped is returned.

Specified by:

skip in class GeneralFileInputStream

Parameters:

n - the number of bytes to be skipped.

Returns:

the actual number of bytes skipped.

Throws:

java.io.IOException - if an I/O error occurs.

available

public int available()
              throws java.io.IOException

Returns the number of bytes that can be read from this file input stream without blocking.

Specified by:

available in class GeneralFileInputStream

Returns:

the number of bytes that can be read from this file input stream without blocking.

Throws:

java.io.IOException - if an I/O error occurs.

close

public void close()
           throws java.io.IOException

Closes this file input stream and releases any system resources associated with the stream.

If this stream has an associated channel then the channel is closed as well.

Specified by:

close in interface java.io.Closeable

Specified by:

close in class GeneralFileInputStream

Throws:

java.io.IOException - if an I/O error occurs.