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java.lang.Object | +--java.io.InputStream | +--com.sun.media.jai.codec.SeekableStream | +--com.sun.media.jai.codec.FileCacheSeekableStream
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.
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 |
public FileCacheSeekableStream(InputStream stream) throws IOException
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 |
public boolean canSeekBackwards()
true
since all
FileCacheSeekableStream
instances support seeking
backwards.canSeekBackwards
in class SeekableStream
public long getFilePointer()
getFilePointer
in class SeekableStream
public void seek(long pos) throws IOException
seek
in class SeekableStream
pos
- the offset position, measured in bytes from the
beginning of the file, at which to set the file
pointer.IOException
- if pos
is less than
0
or if an I/O error occurs.public int read() throws IOException
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.read
in class SeekableStream
-1
if the end of the
stream is reached.IOException
- if an I/O error occurs.public int read(byte[] b, int off, int len) throws IOException
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.
read
in class SeekableStream
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.-1
if there is no more data because the end of
the stream has been reached.IOException
- if an I/O error occurs.public void close() throws IOException
close
in class InputStream
IOException
- if an I/O error occurs.
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