com.sun.media.jai.codec
Class FileCacheSeekableStream

java.lang.Object
  java.io.InputStream
      com.sun.media.jai.codec.SeekableStream
          com.sun.media.jai.codec.FileCacheSeekableStream

All Implemented Interfaces:

DataInput

public final class FileCacheSeekableStream

extends SeekableStream

A subclass of SeekableStream that may be used to wrap a regular InputStream. Seeking backwards is supported by means of a file cache. In circumstances that do not allow the creation of a temporary file (for example, due to security consideration or the absence of local disk), the MemoryCacheSeekableStream class may be used instead.

The mark() and reset() methods are supported.

This class is not a committed part of the JAI API. It may be removed or changed in future releases of JAI.

Field Summary

Fields inherited from class com.sun.media.jai.codec.SeekableStream

markPos

Constructor Summary

FileCacheSeekableStream(InputStream stream)
Constructs a MemoryCacheSeekableStream that takes its source data from a regular InputStream.

Method Summary

boolean	canSeekBackwards() Returns true since all FileCacheSeekableStream instances support seeking backwards.
void	close() Closes this stream and releases any system resources associated with the stream.
long	getFilePointer() Returns the current offset in this file.
int	read() Reads the next byte of data from the input stream.
int	read(byte[] b, int off, int len) Reads up to len bytes of data from the input stream into an array of bytes.
void	seek(long pos) Sets the file-pointer offset, measured from the beginning of this file, at which the next read occurs.

Methods inherited from class com.sun.media.jai.codec.SeekableStream

finalize, mark, markSupported, readBoolean, readByte, readChar, readCharLE, readDouble, readDoubleLE, readFloat, readFloatLE, readFully, readFully, readInt, readIntLE, readLine, readLong, readLongLE, readShort, readShortLE, readUnsignedByte, readUnsignedInt, readUnsignedIntLE, readUnsignedShort, readUnsignedShortLE, readUTF, reset, skipBytes, wrapInputStream

Methods inherited from class java.io.InputStream

available, read, skip

Methods inherited from class java.lang.Object

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

Constructor Detail

FileCacheSeekableStream

public FileCacheSeekableStream(InputStream stream)
                        throws IOException

Constructs a MemoryCacheSeekableStream that takes its source data from a regular InputStream. Seeking backwards is supported by means of an file cache.

An IOException will be thrown if the attempt to create the cache file fails for any reason.

Method Detail

canSeekBackwards

public boolean canSeekBackwards()

Returns true since all FileCacheSeekableStream instances support seeking backwards.

Overrides:

canSeekBackwards in class SeekableStream

getFilePointer

public long getFilePointer()

Returns the current offset in this file.

Specified by:

getFilePointer in class SeekableStream

Returns:

the offset from the beginning of the file, in bytes, at which the next read occurs.

seek

public void seek(long pos)
          throws IOException

Sets the file-pointer offset, measured from the beginning of this file, at which the next read occurs.

Specified by:

seek in class SeekableStream

Parameters:

pos - the offset position, measured in bytes from the beginning of the file, at which to set the file pointer.

Throws:

IOException - if pos is less than 0 or if an I/O error occurs.

read

public int read()
         throws IOException

Reads the next byte of data from the input stream. The value byte is returned as an int in the range 0 to 255. If no byte is available because the end of the stream has been reached, the value -1 is returned. This method blocks until input data is available, the end of the stream is detected, or an exception is thrown.

Specified by:

read in class SeekableStream

Returns:

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

Throws:

IOException - if an I/O error occurs.

read

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

Specified by:

read in class SeekableStream

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:

IOException - if an I/O error occurs.

close

public void close()
           throws IOException

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

Throws:

IOException - if an I/O error occurs.