com.googlecode.mp4parser

Class DirectFileReadDataSource

java.lang.Object

com.googlecode.mp4parser.DirectFileReadDataSource

All Implemented Interfaces:

DataSource, Closeable, AutoCloseable

public class DirectFileReadDataSource
extends Object
implements DataSource

A DataSource implementation that relies on direct reads from a RandomAccessFile. It should be slower than FileDataSourceImpl but does not incur the implicit file locks of memory mapped I/O on some JVMs. This implementation allows for a more controlled deletion of files and might be preferred when working with temporary files.

See Also:

JDK-4724038 : (fs) Add unmap method to MappedByteBuffer, JDK-6359560 : (fs) File.deleteOnExit() doesn't work when MappedByteBuffer exists (win)

Constructor Summary

Constructors

Constructor and Description
DirectFileReadDataSource(File f)

Method Summary

Modifier and Type	Method and Description
void	close() Tries to free all resources.
ByteBuffer	map(long startPosition, long size) Maps a part of this DataSource into a ByteBuffer.
long	position() Returns the DataSource's current position.
void	position(long nuPos) Sets the DataSource's position.
int	read(ByteBuffer byteBuffer) Reads a sequence of bytes from this channel into the given buffer.
int	readAllInOnce(ByteBuffer byteBuffer)
long	size() Returns the current size of this DataSource.
String	toString()
long	transferTo(long position, long count, WritableByteChannel target) Transfers bytes from this DataSource to the given writable byte channel.

Methods inherited from class java.lang.Object

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

Constructor Detail

DirectFileReadDataSource

public DirectFileReadDataSource(File f)
                         throws IOException

Throws:

IOException

Method Detail

read

public int read(ByteBuffer byteBuffer)
         throws IOException

Description copied from interface: DataSource

Reads a sequence of bytes from this channel into the given buffer. Bytes are read starting at this channel's current position, and then the file position is updated with the number of bytes actually read.

Specified by:

read in interface DataSource

Parameters:

byteBuffer - sink for this read operation

Returns:

number of bytes actually read

Throws:

IOException - If some I/O error occurs

readAllInOnce

public int readAllInOnce(ByteBuffer byteBuffer)
                  throws IOException

Throws:

IOException

size

public long size()
          throws IOException

Description copied from interface: DataSource

Returns the current size of this DataSource.

Specified by:

size in interface DataSource

Returns:

The current size of this DataSource, measured in bytes

Throws:

IOException - If some I/O error occurs

position

public long position()
              throws IOException

Description copied from interface: DataSource

Returns the DataSource's current position.

Specified by:

position in interface DataSource

Returns:

This DataSource's file position, a non-negative integer counting the number of bytes from the beginning of the data to the current position

Throws:

IOException - If some I/O error occurs

position

public void position(long nuPos)
              throws IOException

Description copied from interface: DataSource

Sets the DataSource's position.

Specified by:

position in interface DataSource

Parameters:

nuPos - The new position, a non-negative integer counting the number of bytes from the beginning of the data

Throws:

IOException - If some I/O error occurs

transferTo

public long transferTo(long position,
                       long count,
                       WritableByteChannel target)
                throws IOException

Description copied from interface: DataSource

Transfers bytes from this DataSource to the given writable byte channel. An attempt should be made to read up to count bytes starting at the given position in this DataSource and write them to the target channel. An invocation of this method may or may not transfer all of the requested bytes;

Specified by:

transferTo in interface DataSource

Parameters:

position - The position within the DataSource at which the transfer is to begin; must be non-negative

count - The maximum number of bytes to be transferred; must be non-negative

target - The target channel

Returns:

the actual number of bytes written

Throws:

IOException - If some I/O error occurs

map

public ByteBuffer map(long startPosition,
                      long size)
               throws IOException

Description copied from interface: DataSource

Maps a part of this DataSource into a ByteBuffer. It might utilize an operating system supported memory mapped file or potentially just reads the requested portion of the file into the memory.

Specified by:

map in interface DataSource

Parameters:

startPosition - where the requested block start

size - size of the requested block

Returns:

the requested portion of the DataSource

Throws:

IOException - If some I/O error occurs

close

public void close()
           throws IOException

Description copied from interface: DataSource

Tries to free all resources.

Specified by:

close in interface DataSource

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Throws:

IOException - If some I/O error occurs

toString

public String toString()

Overrides:

toString in class Object