| Methods Summary |
|---|
| public void | close()Closes the stream. Attempts to access a stream that has been
closed may result in IOExceptions 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.
|
| public void | flush()Discards the initial position of the stream prior to the current
stream position. Equivalent to
flushBefore(getStreamPosition()).
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| public void | flushBefore(long pos)Discards the initial portion of the stream prior to the
indicated postion. Attempting to seek to an offset within the
flushed portion of the stream will result in an
IndexOutOfBoundsException.
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.
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| public int | getBitOffset()Returns the current bit offset, as an integer between 0 and 7,
inclusive. The bit offset is updated implicitly by calls to
the readBits 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.
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| public java.nio.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.
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| public long | getFlushedPosition()Returns the earliest position in the stream to which seeking
may be performed. The returned value will be the maximum of
all values passed into previous calls to
flushBefore.
|
| public long | getStreamPosition()Returns the current byte position of the stream. The next read
will take place starting at this offset.
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| public boolean | isCached()Returns true if this ImageInputStream
caches data itself in order to allow seeking backwards.
Applications may consult this in order to decide how frequently,
or whether, to flush in order to conserve cache resources.
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| public boolean | isCachedFile()Returns true if this ImageInputStream
caches data itself in order to allow seeking backwards, and
the cache is kept in a temporary file. Applications may consult
this in order to decide how frequently, or whether, to flush
in order to conserve cache resources.
|
| public boolean | isCachedMemory()Returns true if this ImageInputStream
caches data itself in order to allow seeking backwards, and
the cache is kept in main memory. Applications may consult
this in order to decide how frequently, or whether, to flush
in order to conserve cache resources.
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| public long | length()Returns the total length of the stream, if known. Otherwise,
-1 is returned.
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| public void | mark()Marks a position in the stream to be returned to by a
subsequent call to reset. Unlike a standard
InputStream, all ImageInputStreams
support marking. Additionally, calls to mark and
reset may be nested arbitrarily.
Unlike the mark methods declared by the
Reader and InputStream interfaces, no
readLimit parameter is used. An arbitrary amount
of data may be read following the call to mark.
The bit position used by the readBits method
is saved and restored by each pair of calls to
mark and reset.
Note that it is valid for an ImageReader to call
flushBefore as part of a read operation.
Therefore, if an application calls mark prior to
passing that stream to an ImageReader, the application
should not assume that the marked position will remain valid after
the read operation has completed.
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| public int | read()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.
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| public int | read(byte[] b)Reads up to b.length bytes from the stream, and
stores them into b starting at index 0. The
number of bytes read is returned. If no bytes can be read
because the end of the stream has been reached, -1 is returned.
The bit offset within the stream is reset to zero before
the read occurs.
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| public 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.
The number of bytes read is returned. If no bytes can be read
because the end of the stream has been reached, -1
is returned.
The bit offset within the stream is reset to zero before
the read occurs.
|
| public int | readBit()Reads a single bit from the stream and returns it as an
int with the value 0 or
1. The bit offset is advanced by one and reduced
modulo 8.
|
| public 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. 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.
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| public boolean | readBoolean()Reads a byte from the stream and returns a boolean
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.
|
| public byte | readByte()Reads a byte from the stream and returns it as a
byte 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.
|
| public void | readBytes(javax.imageio.stream.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.
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.
|
| public char | readChar()Equivalent to readUnsignedShort, except that the
result is returned using the char datatype.
The bit offset within the stream is reset to zero before
the read occurs.
|
| public 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.
The bit offset within the stream is reset to zero before
the read occurs.
|
| public 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.
The bit offset within the stream is reset to zero before
the read occurs.
|
| public void | readFully(byte[] b, int off, int len)Reads len 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.
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| public void | readFully(byte[] b)Reads b.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.
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| public 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. 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.
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| public 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. 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.
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| public 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. 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.
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| public 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. 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.
|
| public 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. 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.
|
| public 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. 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.
|
| public 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.
The bit offset within the stream is ignored and treated as
though it were zero.
|
| public java.lang.String | readLine()Reads the next line of text from the input stream. It reads
successive bytes, converting each byte separately into a
character, until it encounters a line terminator or end of
file; the characters read are then returned as a
String. 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.
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| public 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.
The bit offset within the stream is reset to zero before
the read occurs.
|
| public 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.
The bit offset within the stream is reset to zero before
the read occurs.
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| public java.lang.String | readUTF()Reads in a string that has been encoded using a
modified
UTF-8
format. The general contract of readUTF 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))
If the first byte of a group matches the bit pattern
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))
If the first byte of a group matches the pattern
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.
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| public 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.
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.
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| public 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.
The bit offset within the stream is reset to zero before
the read occurs.
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| public 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.
The bit offset within the stream is reset to zero before
the read occurs.
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| public void | reset()Returns the stream pointer to its previous position, including
the bit offset, at the time of the most recent unmatched call
to mark.
Calls to reset without a corresponding call
to mark have no effect.
An IOException will be thrown if the previous
marked position lies in the discarded portion of the stream.
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| public void | seek(long pos)Sets the current stream position to the desired location. The
next read will occur at this location. The bit offset is set
to 0.
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.
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| public void | setBitOffset(int bitOffset)Sets the bit offset to an integer between 0 and 7, inclusive.
The byte offset within the stream, as returned by
getStreamPosition, 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.
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| public void | setByteOrder(java.nio.ByteOrder byteOrder)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).
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| public int | skipBytes(int n)Moves the stream position forward by a given number of bytes. It
is possible that this method will only be able to skip forward
by a smaller number of bytes than requested, for example if the
end of the stream is reached. In all cases, the actual number
of bytes skipped is returned. The bit offset is set to zero
prior to advancing the position.
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| public long | skipBytes(long n)Moves the stream position forward by a given number of bytes.
This method is identical to skipBytes(int) except
that it allows for a larger skip distance.
|
