com.sun.media.imageio.stream

Class FileChannelImageInputStream

java.lang.Object

javax.imageio.stream.ImageInputStreamImpl

com.sun.media.imageio.stream.FileChannelImageInputStream

All Implemented Interfaces:

Closeable, DataInput, AutoCloseable, ImageInputStream

public class FileChannelImageInputStream
extends ImageInputStreamImpl

A class which implements ImageInputStream using a FileChannel as the eventual data source. The channel contents are assumed to be stable during the lifetime of the object.

Memory mapping and new I/O view Buffers are used to read the data. Only methods which provide significant performance improvement with respect to the superclass implementation are overridden. Overridden methods are not commented individually unless some noteworthy aspect of the implementation must be described.

The methods of this class are not synchronized.

See Also:

ImageInputStream, java.nio, FileChannel

Field Summary

Fields

Modifier and Type	Field and Description
private FileChannel	channel The FileChannel data source.
private MappedByteBuffer	mappedBuffer A memory mapping of all or part of the channel.
private long	mappedPos The stream position of the mapping.
private long	mappedUpperBound The stream position least upper bound of the mapping.

Fields inherited from class javax.imageio.stream.ImageInputStreamImpl

bitOffset, byteOrder, flushedPos, streamPos

Constructor Summary

Constructors

Constructor and Description
FileChannelImageInputStream(FileChannel channel) Constructs a FileChannelImageInputStream from a FileChannel.

Method Summary

Methods

Modifier and Type	Method and Description
void	close() Invokes the superclass method and sets the internal reference to the source FileChannel to null.
private MappedByteBuffer	getMappedBuffer(int len) Returns a MappedByteBuffer which memory maps at least from the channel position corresponding to the current stream position to len bytes beyond.
long	length() Returns the number of bytes currently in the FileChannel.
int	read()
int	read(byte[] b, int off, int len)
void	readFully(char[] c, int off, int len)
void	readFully(double[] d, int off, int len)
void	readFully(float[] f, int off, int len)
void	readFully(int[] i, int off, int len)
void	readFully(long[] l, int off, int len)
void	readFully(short[] s, int off, int len)
void	seek(long pos) Invokes the superclass method and sets the position within the memory mapped buffer.
void	setByteOrder(ByteOrder networkByteOrder)

Methods inherited from class javax.imageio.stream.ImageInputStreamImpl

checkClosed, finalize, flush, flushBefore, getBitOffset, getByteOrder, getFlushedPosition, getStreamPosition, isCached, isCachedFile, isCachedMemory, mark, read, readBit, readBits, readBoolean, readByte, readBytes, readChar, readDouble, readFloat, readFully, readFully, readInt, readLine, readLong, readShort, readUnsignedByte, readUnsignedInt, readUnsignedShort, readUTF, reset, setBitOffset, skipBytes, skipBytes

Methods inherited from class java.lang.Object

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

Field Detail

channel

private FileChannel channel

The FileChannel data source.

mappedBuffer

private MappedByteBuffer mappedBuffer

A memory mapping of all or part of the channel.

mappedPos

private long mappedPos

The stream position of the mapping.

mappedUpperBound

private long mappedUpperBound

The stream position least upper bound of the mapping.

Constructor Detail

FileChannelImageInputStream

public FileChannelImageInputStream(FileChannel channel)
                            throws IOException

Constructs a FileChannelImageInputStream from a FileChannel. The initial position of the stream stream is taken to be the position of the FileChannel parameter when this constructor is invoked. The stream and flushed positions are therefore both initialized to channel.position().

Parameters:

channel - the source FileChannel.

Throws:

IllegalArgumentException - if channel is null or is not open.

IOException - if a method invoked on channel throws an IOException.

Method Detail

getMappedBuffer

private MappedByteBuffer getMappedBuffer(int len)
                                  throws IOException

Returns a MappedByteBuffer which memory maps at least from the channel position corresponding to the current stream position to len bytes beyond. A new buffer is created only if necessary.

Parameters:

len - The number of bytes required beyond the current stream position.

Throws:

IOException

read

public int read()
         throws IOException

Specified by:

read in interface ImageInputStream

Specified by:

read in class ImageInputStreamImpl

Throws:

IOException

read

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

Specified by:

read in interface ImageInputStream

Specified by:

read in class ImageInputStreamImpl

Throws:

IOException

close

public void close()
           throws IOException

Invokes the superclass method and sets the internal reference to the source FileChannel to null. The source FileChannel is not closed.

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Specified by:

close in interface ImageInputStream

Overrides:

close in class ImageInputStreamImpl

Throws:

IOException - if an error occurs.

readFully

public void readFully(char[] c,
             int off,
             int len)
               throws IOException

Specified by:

readFully in interface ImageInputStream

Overrides:

readFully in class ImageInputStreamImpl

Throws:

IOException

readFully

public void readFully(short[] s,
             int off,
             int len)
               throws IOException

Specified by:

readFully in interface ImageInputStream

Overrides:

readFully in class ImageInputStreamImpl

Throws:

IOException

readFully

public void readFully(int[] i,
             int off,
             int len)
               throws IOException

Specified by:

readFully in interface ImageInputStream

Overrides:

readFully in class ImageInputStreamImpl

Throws:

IOException

readFully

public void readFully(long[] l,
             int off,
             int len)
               throws IOException

Specified by:

readFully in interface ImageInputStream

Overrides:

readFully in class ImageInputStreamImpl

Throws:

IOException

readFully

public void readFully(float[] f,
             int off,
             int len)
               throws IOException

Specified by:

readFully in interface ImageInputStream

Overrides:

readFully in class ImageInputStreamImpl

Throws:

IOException

readFully

public void readFully(double[] d,
             int off,
             int len)
               throws IOException

Specified by:

readFully in interface ImageInputStream

Overrides:

readFully in class ImageInputStreamImpl

Throws:

IOException

length

public long length()

Returns the number of bytes currently in the FileChannel. If an IOException is encountered when querying the channel's size, -1L will be returned.

Specified by:

length in interface ImageInputStream

Overrides:

length in class ImageInputStreamImpl

Returns:

The number of bytes in the channel -1L to indicate unknown length.

seek

public void seek(long pos)
          throws IOException

Invokes the superclass method and sets the position within the memory mapped buffer. A new region is mapped if necessary. The position of the source FileChannel is not changed, i.e., FileChannel.position(long) is not invoked.

Specified by:

seek in interface ImageInputStream

Overrides:

seek in class ImageInputStreamImpl

Throws:

IOException

setByteOrder

public void setByteOrder(ByteOrder networkByteOrder)

Specified by:

setByteOrder in interface ImageInputStream

Overrides:

setByteOrder in class ImageInputStreamImpl