Class SeekableStreamAdapter

java.lang.Object

java.io.InputStream

org.apache.xmlgraphics.image.codec.util.SeekableStream

org.apache.xmlgraphics.image.loader.util.SeekableStreamAdapter

All Implemented Interfaces:

Closeable, DataInput, AutoCloseable

public class SeekableStreamAdapter
extends SeekableStream

Adapter which provides a SeekableStream interface over an ImageInputStream.

Field Summary

Fields inherited from class SeekableStream

markPos

Constructor Summary

Constructors

Constructor	Description
SeekableStreamAdapter(ImageInputStream iin)	Main constructor

Method Summary

Modifier and Type	Method	Description
boolean	canSeekBackwards()	Returns true if this object supports calls to seek(pos) with an offset pos smaller than the current offset, as returned by getFilePointer.
long	getFilePointer()	Returns the current offset in this stream.
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 offset, measured from the beginning of this stream, at which the next read occurs.
int	skipBytes(int n)	Attempts to skip over n bytes of input discarding the skipped bytes.

Methods inherited from class 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, wrapInputStream

Methods inherited from class InputStream

available, close, nullInputStream, read, readAllBytes, readNBytes, readNBytes, skip, skipNBytes, transferTo

Methods inherited from class Object

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

Constructor Details

SeekableStreamAdapter

public SeekableStreamAdapter(ImageInputStream iin)

Main constructor

Parameters:

iin - the ImageInputStream to operate on

Method Details

getFilePointer

public long getFilePointer()
                    throws IOException

Returns the current offset in this stream.

Specified by:

getFilePointer in class SeekableStream

Returns:

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

Throws:

IOException - 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.

A subclass must provide an implementation of this method.

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 stream 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 stream, 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 stream, then an IOException is thrown. In particular, an IOException is thrown if the input stream has been closed.

A subclass must provide an implementation of this method.

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.

seek

public void seek(long pos)
          throws IOException

Sets the offset, measured from the beginning of this stream, at which the next read occurs.

If canSeekBackwards() returns false, then setting pos to an offset smaller than the current value of getFilePointer() will have no effect.

Specified by:

seek in class SeekableStream

Parameters:

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

Throws:

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

canSeekBackwards

public boolean canSeekBackwards()

Returns true if this object supports calls to seek(pos) with an offset pos smaller than the current offset, as returned by getFilePointer.

Overrides:

canSeekBackwards in class SeekableStream

skipBytes

public int skipBytes(int n)
              throws IOException

Attempts to skip over n bytes of input discarding the skipped bytes.

This method may skip over some smaller number of bytes, possibly zero. This may result from any of a number of conditions; reaching end of stream before n bytes have been skipped is only one possibility. This method never throws an EOFException. The actual number of bytes skipped is returned. If n is negative, no bytes are skipped.

Specified by:

skipBytes in interface DataInput

Overrides:

skipBytes in class SeekableStream

Parameters:

n - the number of bytes to be skipped.

Returns:

the actual number of bytes skipped.

Throws:

IOException - if an I/O error occurs.