xmlgraphics-commons 1.3.1

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

java.lang.Object
  extended by java.io.InputStream
      extended by org.apache.xmlgraphics.image.codec.util.SeekableStream
          extended by org.apache.xmlgraphics.image.loader.util.SeekableStreamAdapter
All Implemented Interfaces:
java.io.Closeable, java.io.DataInput

public class SeekableStreamAdapter
extends SeekableStream

Adapter which provides a SeekableStream interface over an ImageInputStream.


Field Summary
 
Fields inherited from class org.apache.xmlgraphics.image.codec.util.SeekableStream
markPos
 
Constructor Summary
SeekableStreamAdapter(javax.imageio.stream.ImageInputStream iin)
          Main constructor
 
Method Summary
 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 org.apache.xmlgraphics.image.codec.util.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 java.io.InputStream
available, close, read, skip
 
Methods inherited from class java.lang.Object
clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

SeekableStreamAdapter

public SeekableStreamAdapter(javax.imageio.stream.ImageInputStream iin)
Main constructor

Parameters:
iin - the ImageInputStream to operate on
Method Detail

getFilePointer

public long getFilePointer()
                    throws java.io.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:
java.io.IOException - if an I/O error occurs.

read

public int read()
         throws java.io.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:
java.io.IOException - if an I/O error occurs.

read

public int read(byte[] b,
                int off,
                int len)
         throws java.io.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:
java.io.IOException - if an I/O error occurs.

seek

public void seek(long pos)
          throws java.io.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:
java.io.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 java.io.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 java.io.DataInput
Overrides:
skipBytes in class SeekableStream
Parameters:
n - the number of bytes to be skipped.
Returns:
the actual number of bytes skipped.
Throws:
java.io.IOException - if an I/O error occurs.

xmlgraphics-commons 1.3.1

Copyright 1999-2008 The Apache Software Foundation. All Rights Reserved.