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Préférences
Moteurs de recherche
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| JavaTM 2 Platform Std. Ed. v1.4.2
javax.imageio.stream
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| Method Summary | |
void |
close()
Closes the stream. |
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()
Returns true if this ImageInputStream
caches data itself in order to allow seeking backwards. |
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. |
boolean |
isCachedMemory()
Returns true if this ImageInputStream
caches data itself in order to allow seeking backwards, and
the cache is kept in main memory. |
long |
length()
Returns the total length of the stream, if known. |
void |
mark()
Marks a position in the stream to be returned to by a subsequent call to reset. |
int |
read()
Reads a single byte from the stream and returns it as an integer between 0 and 255. |
int |
read(byte[] b)
Reads up to b.length bytes from the stream, and
stores them into b starting at index 0. |
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 0xffffffff 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()
Returns the file pointer to its previous position, including the bit offset, at the time of the most recent unmatched call to mark. |
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)
Moves the stream position forward by a given number of bytes. |
long |
skipBytes(long n)
Moves the stream position forward by a given number of bytes. |
| Method Detail |
public void setByteOrder(ByteOrder byteOrder)
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).
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.ByteOrder,
getByteOrder(),
readBits(int)public ByteOrder getByteOrder()
java.nio.ByteOrder enumeration.
ByteOrder.BIG_ENDIAN or
ByteOrder.LITTLE_ENDIAN, indicating which byte
order is being used.ByteOrder,
setByteOrder(java.nio.ByteOrder)
public int read()
throws IOException
The bit offset within the stream is reset to zero before the read occurs.
IOException - if an I/O error occurs.
public int read(byte[] b)
throws IOException
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.
b - 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 int read(byte[] b,
int off,
int len)
throws IOException
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.
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.
-1
to indicate EOF.
NullPointerException - if b is
null.
IndexOutOfBoundsException - if off is
negative, len is negative, or off +
len is greater than b.length.
IOException - if an I/O error occurs.public void readBytes(IIOByteBuffer buf, int len) throws IOException
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.
buf - an IIOByteBuffer object to be modified.len - the maximum number of bytes to read.
IndexOutOfBoundsException - if len is
negative.
NullPointerException - if buf is
null.
IOException - if an I/O error occurs.
public boolean readBoolean()
throws IOException
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.
readBoolean in interface DataInputEOFException - if the end of the stream is reached.
IOException - if an I/O error occurs.
public byte readByte()
throws IOException
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.
EOFException - if the end of the stream is reached.
IOException - if an I/O error occurs.
public int readUnsignedByte()
throws IOException
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.
readUnsignedByte in interface DataInputEOFException - if the end of the stream is reached.
IOException - if an I/O error occurs.
public short readShort()
throws IOException
short value.
The bit offset within the stream is reset to zero before the read occurs.
EOFException - if the stream reaches the end before
reading all the bytes.
IOException - if an I/O error occurs.getByteOrder()
public int readUnsignedShort()
throws IOException
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.
readUnsignedShort in interface DataInputEOFException - if the stream reaches the end before
reading all the bytes.
IOException - if an I/O error occurs.getByteOrder()
public char readChar()
throws IOException
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.
EOFException - if the stream reaches the end before
reading all the bytes.
IOException - if an I/O error occurs.readUnsignedShort()
public int readInt()
throws IOException
int.
The bit offset within the stream is ignored and treated as though it were zero.
EOFException - if the stream reaches the end before
reading all the bytes.
IOException - if an I/O error occurs.getByteOrder()
public long readUnsignedInt()
throws IOException
0xffffffff 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.
EOFException - if the stream reaches the end before
reading all the bytes.
IOException - if an I/O error occurs.getByteOrder()
public long readLong()
throws IOException
long.
The bit offset within the stream is reset to zero before the read occurs.
EOFException - if the stream reaches the end before
reading all the bytes.
IOException - if an I/O error occurs.getByteOrder()
public float readFloat()
throws IOException
float.
The bit offset within the stream is reset to zero before the read occurs.
EOFException - if the stream reaches the end before
reading all the bytes.
IOException - if an I/O error occurs.getByteOrder()
public double readDouble()
throws IOException
double.
The bit offset within the stream is reset to zero before the read occurs.
readDouble in interface DataInputEOFException - if the stream reaches the end before
reading all the bytes.
IOException - if an I/O error occurs.getByteOrder()public String readLine() throws IOException
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.
IOException - if an I/O error occurs.public String readUTF() throws IOException
readUTF is that
it reads a representation of a Unicode character string encoded
in Java 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.
EOFException - if this stream reaches the end
before reading all the bytes.
UTFDataFormatException - if the bytes do not represent a
valid UTF-8 encoding of a string.
IOException - if an I/O error occurs.
public void readFully(byte[] b,
int off,
int len)
throws IOException
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.
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.
IndexOutOfBoundsException - if off is
negative, len is negative, or off +
len is greater than b.length.
NullPointerException - if b is
null.
EOFException - if the stream reaches the end before
reading all the bytes.
IOException - if an I/O error occurs.
public void readFully(byte[] b)
throws IOException
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.
b - an array of bytes.
NullPointerException - if b is
null.
EOFException - if the stream reaches the end before
reading all the bytes.
IOException - if an I/O error occurs.
public void readFully(short[] s,
int off,
int len)
throws IOException
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.
s - an array of shorts to be written to.off - the starting position withinb to write to.len - the maximum number of shorts to read.
IndexOutOfBoundsException - if off is
negative, len is negative, or off +
len is greater than s.length.
NullPointerException - if s is
null.
EOFException - if the stream reaches the end before
reading all the bytes.
IOException - if an I/O error occurs.
public void readFully(char[] c,
int off,
int len)
throws IOException
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.
c - an array of chars to be written to.off - the starting position withinb to write to.len - the maximum number of chars to read.
IndexOutOfBoundsException - if off is
negative, len is negative, or off +
len is greater than c.length.
NullPointerException - if c is
null.
EOFException - if the stream reaches the end before
reading all the bytes.
IOException - if an I/O error occurs.
public void readFully(int[] i,
int off,
int len)
throws IOException
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.
i - an array of ints to be written to.off - the starting position withinb to write to.len - the maximum number of ints to read.
IndexOutOfBoundsException - if off is
negative, len is negative, or off +
len is greater than i.length.
NullPointerException - if i is
null.
EOFException - if the stream reaches the end before
reading all the bytes.
IOException - if an I/O error occurs.
public void readFully(long[] l,
int off,
int len)
throws IOException
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.
l - an array of longs to be written to.off - the starting position withinb to write to.len - the maximum number of longs to read.
IndexOutOfBoundsException - if off is
negative, len is negative, or off +
len is greater than l.length.
NullPointerException - if l is
null.
EOFException - if the stream reaches the end before
reading all the bytes.
IOException - if an I/O error occurs.
public void readFully(float[] f,
int off,
int len)
throws IOException
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.
f - an array of floats to be written to.off - the starting position withinb to write to.len - the maximum number of floats to read.
IndexOutOfBoundsException - if off is
negative, len is negative, or off +
len is greater than f.length.
NullPointerException - if f is
null.
EOFException - if the stream reaches the end before
reading all the bytes.
IOException - if an I/O error occurs.
public void readFully(double[] d,
int off,
int len)
throws IOException
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.
d - an array of doubles to be written to.off - the starting position withinb to write to.len - the maximum number of doubles to read.
IndexOutOfBoundsException - if off is
negative, len is negative, or off +
len is greater than d.length.
NullPointerException - if d is
null.
EOFException - if the stream reaches the end before
reading all the bytes.
IOException - if an I/O error occurs.
public long getStreamPosition()
throws IOException
IOException - if an I/O error occurs.
public int getBitOffset()
throws IOException
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.
int containing the bit offset between
0 and 7, inclusive.
IOException - if an I/O error occurs.setBitOffset(int)
public void setBitOffset(int bitOffset)
throws IOException
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.
bitOffset - the desired offset, as an int
between 0 and 7, inclusive.
IllegalArgumentException - if bitOffset
is not between 0 and 7, inclusive.
IOException - if an I/O error occurs.getBitOffset()
public int readBit()
throws IOException
int with the value 0 or
1. The bit offset is advanced by one and reduced
modulo 8.
int containing the value 0
or 1.
EOFException - if the stream reaches the end before
reading all the bits.
IOException - if an I/O error occurs.
public long readBits(int numBits)
throws IOException
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.
numBits - 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.
IllegalArgumentException - if numBits
is not between 0 and 64, inclusive.
EOFException - if the stream reaches the end before
reading all the bits.
IOException - if an I/O error occurs.
public long length()
throws IOException
-1 is returned.
long containing the length of the
stream, if known, or else -1.
IOException - if an I/O error occurs.
public int skipBytes(int n)
throws IOException
n - an int containing the number of bytes to
be skipped.
int representing the number of bytes skipped.
IOException - if an I/O error occurs.
public long skipBytes(long n)
throws IOException
skipBytes(int) except
that it allows for a larger skip distance.
n - a long containing the number of bytes to
be skipped.
long representing the number of bytes
skipped.
IOException - if an I/O error occurs.
public void seek(long pos)
throws IOException
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.
pos - a long containing the desired file
pointer position.
IndexOutOfBoundsException - if pos is smaller
than the flushed position.
IOException - if any other I/O error occurs.public void mark()
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 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.
public void reset()
throws IOException
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.
IOException - if an I/O error occurs.
public void flushBefore(long pos)
throws IOException
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.
pos - a long containing the length of the
file prefix that may be flushed.
IndexOutOfBoundsException - if pos lies
in the flushed portion of the stream or past the current stream
position.
IOException - if an I/O error occurs.
public void flush()
throws IOException
flushBefore(getStreamPosition()).
IOException - if an I/O error occurs.public long getFlushedPosition()
flushBefore.
long.public boolean isCached()
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.
true if this ImageInputStream
caches data.isCachedMemory(),
isCachedFile()public boolean isCachedMemory()
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.
true if this ImageInputStream
caches data in main memory.isCached(),
isCachedFile()public boolean isCachedFile()
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.
true if this ImageInputStream
caches data in a temporary file.isCached(),
isCachedMemory()
public void close()
throws IOException
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.
IOException - if an I/O error occurs.