javax.imageio.stream
Class ImageInputStreamImpl

java.lang.Object   
  javax.imageio.stream.ImageInputStreamImpl

All Implemented Interfaces:

DataInput , ImageInputStream

Direct Known Subclasses:

FileCacheImageInputStream , FileImageInputStream , ImageOutputStreamImpl , MemoryCacheImageInputStream

public abstract class ImageInputStreamImpl
extends Object   
implements ImageInputStream   

An abstract class implementing the ImageInputStream interface. This class is designed to reduce the number of methods that must be implemented by subclasses.

In particular, this class handles most or all of the details of byte order interpretation, buffering, mark/reset, discarding, closing, and disposing.

Field Summary

protected int	bitOffset The current bit offset within the stream.
protected ByteOrder	byteOrder The byte order of the stream as an instance of the enumeration class java.nio.ByteOrder, where ByteOrder.BIG_ENDIAN indicates network byte order and ByteOrder.LITTLE_ENDIAN indicates the reverse order.
protected long	flushedPos The position prior to which data may be discarded.
protected long	streamPos The current read position within the stream.

Constructor Summary

ImageInputStreamImpl ()
Constructs an ImageInputStreamImpl.

Method Summary

protected void	checkClosed () Throws an IOException if the stream has been closed.
void	close () Closes the stream.
protected void	finalize () Finalizes this object prior to garbage collection.
void	flush () Discards the initial position of the stream prior to the current stream position.
void	flushBefore (long pos) Discards the initial portion of the stream prior to the indicated postion.
int	getBitOffset () Returns the current bit offset, as an integer between 0 and 7, inclusive.
ByteOrder	getByteOrder () Returns the byte order with which data values will be read from this stream as an instance of the java.nio.ByteOrder enumeration.
long	getFlushedPosition () Returns the earliest position in the stream to which seeking may be performed.
long	getStreamPosition () Returns the current byte position of the stream.
boolean	isCached () Default implementation returns false.
boolean	isCachedFile () Default implementation returns false.
boolean	isCachedMemory () Default implementation returns false.
long	length () Returns -1L to indicate that the stream has unknown length.
void	mark () Pushes the current stream position onto a stack of marked positions.
abstract int	read () Reads a single byte from the stream and returns it as an integer between 0 and 255.
int	read (byte[] b) A convenience method that calls read(b, 0, b.length).
abstract int	read (byte[] b, int off, int len) Reads up to len bytes from the stream, and stores them into b starting at index off.
int	readBit () Reads a single bit from the stream and returns it as an int with the value 0 or 1.
long	readBits (int numBits) Reads a bitstring from the stream and returns it as a long, with the first bit read becoming the most significant bit of the output.
boolean	readBoolean () Reads one input byte and returns true if that byte is nonzero, false if that byte is zero.
byte	readByte () Reads and returns one input byte.
void	readBytes (IIOByteBuffer buf, int len) Reads up to len bytes from the stream, and modifies the supplied IIOByteBuffer to indicate the byte array, offset, and length where the data may be found.
char	readChar () Reads an input char and returns the char value.
double	readDouble () Reads eight input bytes and returns a double value.
float	readFloat () Reads four input bytes and returns a float value.
void	readFully (byte[] b) Reads some bytes from an input stream and stores them into the buffer array b.
void	readFully (byte[] b, int off, int len) Reads len bytes from an input stream.
void	readFully (char[] c, int off, int len) Reads len chars (unsigned 16-bit integers) from the stream according to the current byte order, and stores them into c starting at index off.
void	readFully (double[] d, int off, int len) Reads len doubles (64-bit IEEE double-precision floats) from the stream according to the current byte order, and stores them into d starting at index off.
void	readFully (float[] f, int off, int len) Reads len floats (32-bit IEEE single-precision floats) from the stream according to the current byte order, and stores them into f starting at index off.
void	readFully (int[] i, int off, int len) Reads len ints (signed 32-bit integers) from the stream according to the current byte order, and stores them into i starting at index off.
void	readFully (long[] l, int off, int len) Reads len longs (signed 64-bit integers) from the stream according to the current byte order, and stores them into l starting at index off.
void	readFully (short[] s, int off, int len) Reads len shorts (signed 16-bit integers) from the stream according to the current byte order, and stores them into s starting at index off.
int	readInt () Reads four input bytes and returns an int value.
String	readLine () Reads the next line of text from the input stream.
long	readLong () Reads eight input bytes and returns a long value.
short	readShort () Reads two input bytes and returns a short value.
int	readUnsignedByte () Reads one input byte, zero-extends it to type int, and returns the result, which is therefore in the range 0 through 255.
long	readUnsignedInt () Reads 4 bytes from the stream, and (conceptually) concatenates them according to the current byte order, converts the result to a long, masks it with 0xffffffffL in order to strip off any sign-extension bits, and returns the result as an unsigned long value.
int	readUnsignedShort () Reads two input bytes and returns an int value in the range 0 through 65535.
String	readUTF () Reads in a string that has been encoded using a modified UTF-8 format.
void	reset () Resets the current stream byte and bit positions from the stack of marked positions.
void	seek (long pos) Sets the current stream position to the desired location.
void	setBitOffset (int bitOffset) Sets the bit offset to an integer between 0 and 7, inclusive.
void	setByteOrder (ByteOrder byteOrder) Sets the desired byte order for future reads of data values from this stream.
int	skipBytes (int n) Advances the current stream position by calling seek(getStreamPosition() + n).
long	skipBytes (long n) Advances the current stream position by calling seek(getStreamPosition() + n).

Methods inherited from class java.lang.Object

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

Field Detail

byteOrder

protected ByteOrder    byteOrder

The byte order of the stream as an instance of the enumeration class java.nio.ByteOrder, where ByteOrder.BIG_ENDIAN indicates network byte order and ByteOrder.LITTLE_ENDIAN indicates the reverse order. By default, the value is ByteOrder.BIG_ENDIAN.

streamPos

protected long streamPos

The current read position within the stream. Subclasses are responsible for keeping this value current from any method they override that alters the read position.

bitOffset

protected int bitOffset

The current bit offset within the stream. Subclasses are responsible for keeping this value current from any method they override that alters the bit offset.

flushedPos

protected long flushedPos

The position prior to which data may be discarded. Seeking to a smaller position is not allowed. flushedPos will always be >= 0.

Constructor Detail

ImageInputStreamImpl

public ImageInputStreamImpl()

Constructs an ImageInputStreamImpl.

Method Detail

checkClosed

protected final void checkClosed()
                          throws IOException   

Throws an IOException if the stream has been closed. Subclasses may call this method from any of their methods that require the stream not to be closed.

Throws:

IOException - if the stream is closed.

setByteOrder

public void setByteOrder(ByteOrder    byteOrder)

Description copied from interface: ImageInputStream

Sets the desired byte order for future reads of data values from this stream. For example, the sequence of bytes '0x01 0x02 0x03 0x04' if read as a 4-byte integer would have the value '0x01020304' using network byte order and the value '0x04030201' under the reverse byte order.

The enumeration class java.nio.ByteOrder is used to specify the byte order. A value of ByteOrder.BIG_ENDIAN specifies so-called big-endian or network byte order, in which the high-order byte comes first. Motorola and Sparc processors store data in this format, while Intel processors store data in the reverse ByteOrder.LITTLE_ENDIAN order.

The byte order has no effect on the results returned from the readBits method (or the value written by ImageOutputStream.writeBits).

Specified by:

setByteOrder in interface ImageInputStream

Parameters:

byteOrder - one of ByteOrder.BIG_ENDIAN or java.nio.ByteOrder.LITTLE_ENDIAN, indicating whether network byte order or its reverse will be used for future reads.

See Also:

ByteOrder , ImageInputStream.getByteOrder() , ImageInputStream.readBits(int)

getByteOrder

public ByteOrder    getByteOrder()

Description copied from interface: ImageInputStream

Returns the byte order with which data values will be read from this stream as an instance of the java.nio.ByteOrder enumeration.

Specified by:

getByteOrder in interface ImageInputStream

Returns:

one of ByteOrder.BIG_ENDIAN or ByteOrder.LITTLE_ENDIAN, indicating which byte order is being used.

See Also:

ByteOrder , ImageInputStream.setByteOrder(java.nio.ByteOrder)

read

public abstract int read()
                  throws IOException   

Description copied from interface: ImageInputStream

Reads a single byte from the stream and returns it as an integer between 0 and 255. If the end of the stream is reached, -1 is returned.

The bit offset within the stream is reset to zero before the read occurs.

Specified by:

read in interface ImageInputStream

Returns:

a byte value from the stream, as an int, or -1 to indicate EOF.

Throws:

IOException - if an I/O error occurs.

read

public int read(byte[] b)
         throws IOException   

A convenience method that calls read(b, 0, b.length).

The bit offset within the stream is reset to zero before the read occurs.

Specified by:

read in interface ImageInputStream

Parameters:

b - an array of bytes to be written to.

Returns:

the number of bytes actually read, or -1 to indicate EOF.

Throws:

NullPointerException - if b is null.

IOException - if an I/O error occurs.

read

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

Reads up to len bytes from the stream, and stores them into b starting at index off. If no bytes can be read because the end of the stream has been reached, -1 is returned.

The bit offset within the stream must be reset to zero before the read occurs.

Subclasses must provide an implementation for this method. The subclass implementation should update the stream position before exiting.

Specified by:

read in interface ImageInputStream

Parameters:

b - an array of bytes to be written to.

off - the starting position within b to write to.

len - the maximum number of bytes to read.

Returns:

the number of bytes actually read, or -1 to indicate EOF.

Throws:

IndexOutOfBoundsException - if off is negative, len is negative, or off + len is greater than b.length.

NullPointerException - if b is null.

IOException - if an I/O error occurs.

readBytes

public void readBytes(IIOByteBuffer    buf,
                      int len)
               throws IOException   

Description copied from interface: ImageInputStream

Reads up to len bytes from the stream, and modifies the supplied IIOByteBuffer to indicate the byte array, offset, and length where the data may be found. The caller should not attempt to modify the data found in the IIOByteBuffer.

The bit offset within the stream is reset to zero before the read occurs.

Specified by:

readBytes in interface ImageInputStream

Parameters:

buf - an IIOByteBuffer object to be modified.

len - the maximum number of bytes to read.

Throws:

IOException - if an I/O error occurs.

readBoolean

public boolean readBoolean()
                    throws IOException   

Description copied from interface: DataInput

Reads one input byte and returns true if that byte is nonzero, false if that byte is zero. This method is suitable for reading the byte written by the writeBoolean method of interface DataOutput.

Specified by:

readBoolean in interface DataInput

Specified by:

readBoolean in interface ImageInputStream

Returns:

the boolean value read.

Throws:

EOFException