Class SegmentedImageInputStream
- All Implemented Interfaces:
Closeable,DataInput,AutoCloseable,ImageInputStream
SegmentedImageInputStream provides a view of a
subset of another ImageInputStream consiting of a series
of segments with given starting positions in the source stream and
lengths. The resulting stream behaves like an ordinary
ImageInputStream.
For example, given a ImageInputStream containing
data in a format consisting of a number of sub-streams stored in
non-contiguous sectors indexed by a directory, it is possible to
construct a set of SegmentedImageInputStreams, one for
each sub-stream, that each provide a view of the sectors comprising
a particular stream by providing the positions and lengths of the
stream's sectors as indicated by the directory. The complex
multi-stream structure of the original stream may be ignored by
users of the SegmentedImageInputStream, who see a
separate ImageInputStream for each sub-stream and do not
need to understand the directory structure at all.
For further efficiency, a directory structure such as in the
example described above need not be fully parsed in order to build
a SegmentedImageInputStream. Instead, the
StreamSegmentMapper interface allows the association
between a desired region of the output and an input segment to be
provided dynamically. This mapping might be computed by reading
from a directory in piecemeal fashion in order to avoid consuming
memory resources.
-
Field Summary
Fields inherited from class javax.imageio.stream.ImageInputStreamImpl
bitOffset, byteOrder, flushedPos, streamPos -
Constructor Summary
ConstructorsConstructorDescriptionSegmentedImageInputStream(ImageInputStream stream, long[] segmentPositions, int[] segmentLengths) Constructs aSegmentedImageInputStreamgiven aImageInputStreamas input and a list of the starting positions and lengths of the segments of the source stream.SegmentedImageInputStream(ImageInputStream stream, long[] segmentPositions, int segmentLength, int totalLength) Constructs aSegmentedImageInputStreamgiven aImageInputStreamas input, a list of the starting positions of the segments of the source stream, the common length of each segment, and the total length of the segments.SegmentedImageInputStream(ImageInputStream stream, StreamSegmentMapper mapper) Constructs aSegmentedImageInputStreamgiven aImageInputStreamas input and an instance ofStreamSegmentMapper. -
Method Summary
Methods inherited from class javax.imageio.stream.ImageInputStreamImpl
checkClosed, close, finalize, flush, flushBefore, getBitOffset, getByteOrder, getFlushedPosition, getStreamPosition, isCached, isCachedFile, isCachedMemory, mark, read, readBit, readBits, readBoolean, readByte, readBytes, readChar, readDouble, readFloat, readFully, readFully, readFully, readFully, readFully, readFully, readFully, readFully, readInt, readLine, readLong, readShort, readUnsignedByte, readUnsignedInt, readUnsignedShort, readUTF, reset, seek, setBitOffset, setByteOrder, skipBytes, skipBytes
-
Constructor Details
-
SegmentedImageInputStream
Constructs aSegmentedImageInputStreamgiven aImageInputStreamas input and an instance ofStreamSegmentMapper.- Parameters:
stream- A sourceImageInputStreammapper- An instance of theStreamSegmentMapperinterface.
-
SegmentedImageInputStream
public SegmentedImageInputStream(ImageInputStream stream, long[] segmentPositions, int[] segmentLengths) Constructs aSegmentedImageInputStreamgiven aImageInputStreamas input and a list of the starting positions and lengths of the segments of the source stream.- Parameters:
stream- A sourceImageInputStreamsegmentPositions- An array oflongs giving the starting positions of the segments in the source stream.segmentLengths- An array ofints giving the lengths of segments in the source stream.
-
SegmentedImageInputStream
public SegmentedImageInputStream(ImageInputStream stream, long[] segmentPositions, int segmentLength, int totalLength) Constructs aSegmentedImageInputStreamgiven aImageInputStreamas input, a list of the starting positions of the segments of the source stream, the common length of each segment, and the total length of the segments.This constructor is useful for selecting substreams of sector-oriented file formats in which each segment of the substream (except possibly the final segment) occupies a fixed-length sector.
- Parameters:
stream- A sourceImageInputStreamsegmentPositions- An array oflongs giving the starting positions of the segments in the source stream.segmentLength- The common length of each segment.totalLength- The total length of the source segments.
-
-
Method Details
-
read
Reads the next byte of data from the input stream. The value byte is returned as anintin the range0to255. If no byte is available because the end of the stream has been reached, the value-1is returned. This method blocks until input data is available, the end of the stream is detected, or an exception is thrown.- Specified by:
readin interfaceImageInputStream- Specified by:
readin classImageInputStreamImpl- Returns:
- the next byte of data, or
-1if the end of the stream is reached. - Throws:
IOException- if an I/O error occurs.
-
read
Reads up tolenbytes of data from the input stream into an array of bytes. An attempt is made to read as many aslenbytes, 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 stream is detected, or an exception is thrown.
If
bisnull, aNullPointerExceptionis thrown.If
offis negative, orlenis negative, oroff+lenis greater than the length of the arrayb, then anIndexOutOfBoundsExceptionis thrown.If
lenis zero, then no bytes are read and0is returned; otherwise, there is an attempt to read at least one byte. If no byte is available because the stream is at end of stream, the value-1is returned; otherwise, at least one byte is read and stored intob.The first byte read is stored into element
b[off], the next one intob[off+1], and so on. The number of bytes read is, at most, equal tolen. Let k be the number of bytes actually read; these bytes will be stored in elementsb[off]throughb[off+k-1], leaving elementsb[off+k]throughb[off+len-1]unaffected.In every case, elements
b[0]throughb[off]and elementsb[off+len]throughb[b.length-1]are unaffected.If the first byte cannot be read for any reason other than end of stream, then an
IOExceptionis thrown. In particular, anIOExceptionis thrown if the input stream has been closed.- Specified by:
readin interfaceImageInputStream- Specified by:
readin classImageInputStreamImpl- Parameters:
b- the buffer into which the data is read.off- the start offset in arraybat which the data is written.len- the maximum number of bytes to read.- Returns:
- the total number of bytes read into the buffer, or
-1if there is no more data because the end of the stream has been reached. - Throws:
IOException- if an I/O error occurs.
-
length
public long length()- Specified by:
lengthin interfaceImageInputStream- Overrides:
lengthin classImageInputStreamImpl
-