public abstract class ImageInputStreamImpl extends Object implements ImageInputStream
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.
| Modifier and Type | Field and Description |
|---|---|
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 and Description |
|---|
ImageInputStreamImpl()
Constructs an
ImageInputStreamImpl. |
| Modifier and Type | Method and Description |
|---|---|
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
int 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 a byte from the stream and returns a
boolean
value of true if it is nonzero, false
if it is zero. |
byte |
readByte()
Reads a byte from the stream and returns it as a
byte value. |
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()
Equivalent to
readUnsignedShort, except that the
result is returned using the char datatype. |
double |
readDouble()
Reads 8 bytes from the stream, and (conceptually) concatenates
them according to the current byte order and returns the result
as a
double. |
float |
readFloat()
Reads 4 bytes from the stream, and (conceptually) concatenates
them according to the current byte order and returns the result
as a
float. |
void |
readFully(byte[] b)
Reads
b.length bytes from the stream, and stores them
into b starting at index 0. |
void |
readFully(byte[] b,
int off,
int len)
Reads
len bytes from the stream, and stores them
into b starting at index off. |
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 4 bytes from the stream, and (conceptually) concatenates
them according to the current byte order and returns the result
as an
int. |
String |
readLine()
Reads the next line of text from the input stream.
|
long |
readLong()
Reads 8 bytes from the stream, and (conceptually) concatenates
them according to the current byte order and returns the result
as a
long. |
short |
readShort()
Reads two bytes from the stream, and (conceptually)
concatenates them according to the current byte order, and
returns the result as a
short value. |
int |
readUnsignedByte()
Reads a byte from the stream, and (conceptually) converts it to
an int, masks it with
0xff in order to strip off
any sign-extension bits, and returns it as a byte
value. |
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 bytes from the stream, and (conceptually)
concatenates them according to the current byte order, converts
the resulting value to an
int, masks it with
0xffff in order to strip off any sign-extension
buts, and returns the result as an unsigned int
value. |
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). |
protected ByteOrder byteOrder
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.protected long streamPos
protected int bitOffset
protected long flushedPos
flushedPos
will always be >= 0.public ImageInputStreamImpl()
ImageInputStreamImpl.protected final void checkClosed()
throws IOException
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.IOException - if the stream is closed.public void setByteOrder(ByteOrder byteOrder)
ImageInputStream 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).
setByteOrder in interface ImageInputStreambyteOrder - 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.ByteOrder,
ImageInputStream.getByteOrder(),
ImageInputStream.readBits(int)public ByteOrder getByteOrder()
ImageInputStreamjava.nio.ByteOrder enumeration.getByteOrder in interface ImageInputStreamByteOrder.BIG_ENDIAN or
ByteOrder.LITTLE_ENDIAN, indicating which byte
order is being used.ByteOrder,
ImageInputStream.setByteOrder(java.nio.ByteOrder)public abstract int read()
throws IOException
int between 0 and 255. If EOF is reached,
-1 is returned.
Subclasses must provide an implementation for this method. The subclass implementation should update the stream position before exiting.
The bit offset within the stream must be reset to zero before the read occurs.
read in interface ImageInputStream-1
if EOF is reached.IOException - if the stream has been closed.public int read(byte[] b)
throws IOException
read(b, 0, b.length).
The bit offset within the stream is reset to zero before the read occurs.
read in interface ImageInputStreamb - an array of bytes to be written to.-1
to indicate EOF.NullPointerException - if b is
null.IOException - if an I/O error occurs.public abstract int read(byte[] b,
int off,
int len)
throws IOException
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.
read in interface ImageInputStreamb - 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.-1
to indicate EOF.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.public void readBytes(IIOByteBuffer buf, int len) throws IOException
ImageInputStreamlen 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.
readBytes in interface ImageInputStreambuf - an IIOByteBuffer object to be modified.len - the maximum number of bytes to read.IOException - if an I/O error occurs.public boolean readBoolean()
throws IOException
ImageInputStreamboolean
value of true if it is nonzero, false
if it is zero.
The bit offset within the stream is reset to zero before the read occurs.
readBoolean in interface DataInputreadBoolean in interface ImageInputStreamIOException - if an I/O error occurs.public byte readByte()
throws IOException
ImageInputStreambyte value. Byte values between 0x00
and 0x7f represent integer values between
0 and 127. Values between
0x80 and 0xff represent negative
values from -128 to /1.
The bit offset within the stream is reset to zero before the read occurs.
readByte in interface DataInputreadByte in interface ImageInputStreamIOException - if an I/O error occurs.public int readUnsignedByte()
throws IOException
ImageInputStream0xff in order to strip off
any sign-extension bits, and returns it as a byte
value.
Thus, byte values between 0x00 and
0x7f are simply returned as integer values between
0 and 127. Values between
0x80 and 0xff, which normally
represent negative bytevalues, will be mapped into
positive integers between 128 and
255.
The bit offset within the stream is reset to zero before the read occurs.
readUnsignedByte in interface DataInputreadUnsignedByte in interface ImageInputStreamIOException - if an I/O error occurs.public short readShort()
throws IOException
ImageInputStreamshort value.
The bit offset within the stream is reset to zero before the read occurs.
readShort in interface DataInputreadShort in interface ImageInputStreamIOException - if an I/O error occurs.ImageInputStream.getByteOrder()public int readUnsignedShort()
throws IOException
ImageInputStreamint, masks it with
0xffff in order to strip off any sign-extension
buts, and returns the result as an unsigned int
value.
The bit offset within the stream is reset to zero before the read occurs.
readUnsignedShort in interface DataInputreadUnsignedShort in interface ImageInputStreamIOException - if an I/O error occurs.ImageInputStream.getByteOrder()public char readChar()
throws IOException
ImageInputStreamreadUnsignedShort, except that the
result is returned using the char datatype.
The bit offset within the stream is reset to zero before the read occurs.
readChar in interface DataInputreadChar in interface ImageInputStreamIOException - if an I/O error occurs.ImageInputStream.readUnsignedShort()public int readInt()
throws IOException
ImageInputStreamint.
The bit offset within the stream is ignored and treated as though it were zero.
readInt in interface DataInputreadInt in interface ImageInputStreamIOException - if an I/O error occurs.ImageInputStream.getByteOrder()public long readUnsignedInt()
throws IOException
ImageInputStream0xffffffffL in order to
strip off any sign-extension bits, and returns the result as an
unsigned long value.
The bit offset within the stream is reset to zero before the read occurs.
readUnsignedInt in interface ImageInputStreamIOException - if an I/O error occurs.ImageInputStream.getByteOrder()public long readLong()
throws IOException
ImageInputStreamlong.
The bit offset within the stream is reset to zero before the read occurs.
readLong in interface DataInputreadLong in interface ImageInputStreamIOException - if an I/O error occurs.ImageInputStream.getByteOrder()public float readFloat()
throws IOException
ImageInputStreamfloat.
The bit offset within the stream is reset to zero before the read occurs.
readFloat in interface DataInputreadFloat in interface ImageInputStreamIOException - if an I/O error occurs.ImageInputStream.getByteOrder()public double readDouble()
throws IOException
ImageInputStreamdouble.
The bit offset within the stream is reset to zero before the read occurs.
readDouble in interface DataInputreadDouble in interface ImageInputStreamIOException - if an I/O error occurs.ImageInputStream.getByteOrder()public String readLine() throws IOException
ImageInputStreamString. Note that because this method processes
bytes, it does not support input of the full Unicode character
set.
If end of file is encountered before even one byte can be
read, then null is returned. Otherwise, each byte
that is read is converted to type char by
zero-extension. If the character '\n' is
encountered, it is discarded and reading ceases. If the
character '\r' is encountered, it is discarded
and, if the following byte converts to the character
'\n', then that is discarded also; reading then
ceases. If end of file is encountered before either of the
characters '\n' and '\r' is
encountered, reading ceases. Once reading has ceased, a
String is returned that contains all the
characters read and not discarded, taken in order. Note that
every character in this string will have a value less than
\u0100, that is, (char)256.
The bit offset within the stream is reset to zero before the read occurs.
readLine in interface DataInputreadLine in interface ImageInputStreamIOException - if an I/O error occurs.public String readUTF() throws IOException
ImageInputStreamreadUTF is that
it reads a representation of a Unicode character string encoded
in modified UTF-8 format; this string of characters is
then returned as a String.
First, two bytes are read and used to construct an unsigned
16-bit integer in the manner of the
readUnsignedShort method, using network byte order
(regardless of the current byte order setting). This integer
value is called the UTF length and specifies the number
of additional bytes to be read. These bytes are then converted
to characters by considering them in groups. The length of each
group is computed from the value of the first byte of the
group. The byte following a group, if any, is the first byte of
the next group.
If the first byte of a group matches the bit pattern
0xxxxxxx (where x means "may be
0 or 1"), then the group consists of
just that byte. The byte is zero-extended to form a character.
If the first byte of a group matches the bit pattern
110xxxxx, then the group consists of that byte
a and a second byte b. If there is no
byte b (because byte a was the last
of the bytes to be read), or if byte b does not
match the bit pattern 10xxxxxx, then a
UTFDataFormatException is thrown. Otherwise, the
group is converted to the character:
(char)(((a& 0x1F) << 6) | (b & 0x3F))
1110xxxx, then the group consists of that byte
a and two more bytes b and
c. If there is no byte c (because
byte a was one of the last two of the bytes to be
read), or either byte b or byte c
does not match the bit pattern 10xxxxxx, then a
UTFDataFormatException is thrown. Otherwise, the
group is converted to the character:
(char)(((a & 0x0F) << 12) | ((b & 0x3F) << 6) | (c & 0x3F))
1111xxxx or the pattern 10xxxxxx,
then a UTFDataFormatException is thrown.
If end of file is encountered at any time during this
entire process, then an EOFException is thrown.
After every group has been converted to a character by this
process, the characters are gathered, in the same order in
which their corresponding groups were read from the input
stream, to form a String, which is returned.
The current byte order setting is ignored.
The bit offset within the stream is reset to zero before the read occurs.
Note: This method should not be used in the implementation of image formats that use standard UTF-8, because the modified UTF-8 used here is incompatible with standard UTF-8.
readUTF in interface DataInputreadUTF in interface ImageInputStreamIOException - if an I/O error occurs.public void readFully(byte[] b,
int off,
int len)
throws IOException
ImageInputStreamlen bytes from the stream, and stores them
into b starting at index off.
If the end of the stream is reached, an EOFException
will be thrown.
The bit offset within the stream is reset to zero before the read occurs.
readFully in interface DataInputreadFully in interface ImageInputStreamb - 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.IOException - if an I/O error occurs.public void readFully(byte[] b)
throws IOException
ImageInputStreamb.length bytes from the stream, and stores them
into b starting at index 0.
If the end of the stream is reached, an EOFException
will be thrown.
The bit offset within the stream is reset to zero before the read occurs.
readFully in interface DataInputreadFully in interface ImageInputStreamb - an array of bytes.IOException - if an I/O error occurs.public void readFully(short[] s,
int off,
int len)
throws IOException
ImageInputStreamlen shorts (signed 16-bit integers) from the
stream according to the current byte order, and
stores them into s starting at index
off. If the end of the stream is reached, an
EOFException will be thrown.
The bit offset within the stream is reset to zero before the read occurs.
readFully in interface ImageInputStreams - an array of shorts to be written to.off - the starting position withinb to write to.len - the maximum number of shorts to read.IOException - if an I/O error occurs.public void readFully(char[] c,
int off,
int len)
throws IOException
ImageInputStreamlen chars (unsigned 16-bit integers) from the
stream according to the current byte order, and
stores them into c starting at index
off. If the end of the stream is reached, an
EOFException will be thrown.
The bit offset within the stream is reset to zero before the read occurs.
readFully in interface ImageInputStreamc - an array of chars to be written to.off - the starting position withinb to write to.len - the maximum number of chars to read.IOException - if an I/O error occurs.public void readFully(int[] i,
int off,
int len)
throws IOException
ImageInputStreamlen ints (signed 32-bit integers) from the
stream according to the current byte order, and
stores them into i starting at index
off. If the end of the stream is reached, an
EOFException will be thrown.
The bit offset within the stream is reset to zero before the read occurs.
readFully in interface ImageInputStreami - an array of ints to be written to.off - the starting position withinb to write to.len - the maximum number of ints to read.IOException - if an I/O error occurs.public void readFully(long[] l,
int off,
int len)
throws IOException
ImageInputStreamlen longs (signed 64-bit integers) from the
stream according to the current byte order, and
stores them into l starting at index
off. If the end of the stream is reached, an
EOFException will be thrown.
The bit offset within the stream is reset to zero before the read occurs.
readFully in interface ImageInputStreaml - an array of longs to be written to.off - the starting position withinb to write to.len - the maximum number of longs to read.IOException - if an I/O error occurs.public void readFully(float[] f,
int off,
int len)
throws IOException
ImageInputStreamlen 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. If the end of the stream is reached,
an EOFException will be thrown.
The bit offset within the stream is reset to zero before the read occurs.
readFully in interface ImageInputStreamf - an array of floats to be written to.off - the starting position withinb to write to.len - the maximum number of floats to read.IOException - if an I/O error occurs.public void readFully(double[] d,
int off,
int len)
throws IOException
ImageInputStreamlen 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. If the end of the stream is reached,
an EOFException will be thrown.
The bit offset within the stream is reset to zero before the read occurs.
readFully in interface ImageInputStreamd - an array of doubles to be written to.off - the starting position withinb to write to.len - the maximum number of doubles to read.IOException - if an I/O error occurs.public long getStreamPosition()
throws IOException
ImageInputStreamgetStreamPosition in interface ImageInputStreamIOException - if an I/O error occurs.public int getBitOffset()
throws IOException
ImageInputStreamreadBits method. A value of 0 indicates the
most-significant bit, and a value of 7 indicates the least
significant bit, of the byte being read.
The bit offset is set to 0 when a stream is first
opened, and is reset to 0 by calls to seek,
skipBytes, or any read or
readFully method.
getBitOffset in interface ImageInputStreamint containing the bit offset between
0 and 7, inclusive.IOException - if an I/O error occurs.ImageInputStream.setBitOffset(int)public void setBitOffset(int bitOffset)
throws IOException
ImageInputStreamgetStreamPosition, is left unchanged.
A value of 0 indicates the
most-significant bit, and a value of 7 indicates the least
significant bit, of the byte being read.setBitOffset in interface ImageInputStreambitOffset - the desired offset, as an int
between 0 and 7, inclusive.IOException - if an I/O error occurs.ImageInputStream.getBitOffset()public int readBit()
throws IOException
ImageInputStreamint with the value 0 or
1. The bit offset is advanced by one and reduced
modulo 8.readBit in interface ImageInputStreamint containing the value 0
or 1.IOException - if an I/O error occurs.public long readBits(int numBits)
throws IOException
ImageInputStreamlong, with the first bit read becoming the most
significant bit of the output. The read starts within the byte
indicated by getStreamPosition, at the bit given
by getBitOffset. The bit offset is advanced by
numBits and reduced modulo 8.
The byte order of the stream has no effect on this method. The return value of this method is constructed as though the bits were read one at a time, and shifted into the right side of the return value, as shown by the following pseudo-code:
long accum = 0L;
for (int i = 0; i < numBits; i++) {
accum <<= 1; // Shift left one bit to make room
accum |= readBit();
}
Note that the result of readBits(32) may thus not
be equal to that of readInt() if a reverse network
byte order is being used (i.e., getByteOrder() ==
false).
If the end of the stream is encountered before all the bits
have been read, an EOFException is thrown.
readBits in interface ImageInputStreamnumBits - the number of bits to read, as an int
between 0 and 64, inclusive.long with the last bit
read stored in the least significant bit.IOException - if an I/O error occurs.public long length()
-1L to indicate that the stream has unknown
length. Subclasses must override this method to provide actual
length information.length in interface ImageInputStreampublic int skipBytes(int n)
throws IOException
seek(getStreamPosition() + n).
The bit offset is reset to zero.
skipBytes in interface DataInputskipBytes in interface ImageInputStreamn - the number of bytes to seek forward.int representing the number of bytes
skipped.IOException - if getStreamPosition
throws an IOException when computing either
the starting or ending position.public long skipBytes(long n)
throws IOException
seek(getStreamPosition() + n).
The bit offset is reset to zero.
skipBytes in interface ImageInputStreamn - the number of bytes to seek forward.long representing the number of bytes
skipped.IOException - if getStreamPosition
throws an IOException when computing either
the starting or ending position.public void seek(long pos)
throws IOException
ImageInputStream An IndexOutOfBoundsException will be thrown if
pos is smaller than the flushed position (as
returned by getflushedPosition).
It is legal to seek past the end of the file; an
EOFException will be thrown only if a read is
performed.
seek in interface ImageInputStreampos - a long containing the desired file
pointer position.IOException - if any other I/O error occurs.public void mark()
mark in interface ImageInputStreampublic void reset()
throws IOException
An IOException will be thrown if the previous
marked position lies in the discarded portion of the stream.
reset in interface ImageInputStreamIOException - if an I/O error occurs.public void flushBefore(long pos)
throws IOException
ImageInputStreamIndexOutOfBoundsException.
Calling flushBefore may allow classes
implementing this interface to free up resources such as memory
or disk space that are being used to store data from the
stream.
flushBefore in interface ImageInputStreampos - a long containing the length of the
stream prefix that may be flushed.IOException - if an I/O error occurs.public void flush()
throws IOException
ImageInputStreamflushBefore(getStreamPosition()).flush in interface ImageInputStreamIOException - if an I/O error occurs.public long getFlushedPosition()
ImageInputStreamflushBefore.getFlushedPosition in interface ImageInputStreamlong.public boolean isCached()
isCached in interface ImageInputStreamtrue if this ImageInputStream
caches data.ImageInputStream.isCachedMemory(),
ImageInputStream.isCachedFile()public boolean isCachedMemory()
isCachedMemory in interface ImageInputStreamtrue if this ImageInputStream
caches data in main memory.ImageInputStream.isCached(),
ImageInputStream.isCachedFile()public boolean isCachedFile()
isCachedFile in interface ImageInputStreamtrue if this ImageInputStream
caches data in a temporary file.ImageInputStream.isCached(),
ImageInputStream.isCachedMemory()public void close()
throws IOException
ImageInputStreamIOExceptions or incorrect
behavior. Calling this method may allow classes implementing
this interface to release resources associated with the stream
such as memory, disk space, or file descriptors.close in interface Closeableclose in interface AutoCloseableclose in interface ImageInputStreamIOException - if an I/O error occurs.protected void finalize()
throws Throwable
close method is called to close any open input
source. This method should not be called from application
code.