- java.lang.Object
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- javax.imageio.stream.ImageInputStreamImpl
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- All Implemented Interfaces:
- Closeable, DataInput, AutoCloseable, ImageInputStream
- Direct Known Subclasses:
- FileCacheImageInputStream, FileImageInputStream, ImageOutputStreamImpl, MemoryCacheImageInputStream
public abstract class ImageInputStreamImpl extends Object implements ImageInputStream
An abstract class implementing theImageInputStream
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.
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Field Summary
Fields 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 classjava.nio.ByteOrder
, whereByteOrder.BIG_ENDIAN
indicates network byte order andByteOrder.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.
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Constructor Summary
Constructors Constructor and Description ImageInputStreamImpl()
Constructs anImageInputStreamImpl
.
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Method Summary
Methods Modifier and Type Method and Description protected void
checkClosed()
Throws anIOException
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 thejava.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 anint
between 0 and 255.int
read(byte[] b)
A convenience method that callsread(b, 0, b.length)
.abstract int
read(byte[] b, int off, int len)
Reads up tolen
bytes from the stream, and stores them intob
starting at indexoff
.int
readBit()
Reads a single bit from the stream and returns it as anint
with the value0
or1
.long
readBits(int numBits)
Reads a bitstring from the stream and returns it as along
, with the first bit read becoming the most significant bit of the output.boolean
readBoolean()
Reads a byte from the stream and returns aboolean
value oftrue
if it is nonzero,false
if it is zero.byte
readByte()
Reads a byte from the stream and returns it as abyte
value.void
readBytes(IIOByteBuffer buf, int len)
Reads up tolen
bytes from the stream, and modifies the suppliedIIOByteBuffer
to indicate the byte array, offset, and length where the data may be found.char
readChar()
Equivalent toreadUnsignedShort
, except that the result is returned using thechar
datatype.double
readDouble()
Reads 8 bytes from the stream, and (conceptually) concatenates them according to the current byte order and returns the result as adouble
.float
readFloat()
Reads 4 bytes from the stream, and (conceptually) concatenates them according to the current byte order and returns the result as afloat
.void
readFully(byte[] b)
Readsb.length
bytes from the stream, and stores them intob
starting at index0
.void
readFully(byte[] b, int off, int len)
Readslen
bytes from the stream, and stores them intob
starting at indexoff
.void
readFully(char[] c, int off, int len)
Readslen
chars (unsigned 16-bit integers) from the stream according to the current byte order, and stores them intoc
starting at indexoff
.void
readFully(double[] d, int off, int len)
Readslen
doubles (64-bit IEEE double-precision floats) from the stream according to the current byte order, and stores them intod
starting at indexoff
.void
readFully(float[] f, int off, int len)
Readslen
floats (32-bit IEEE single-precision floats) from the stream according to the current byte order, and stores them intof
starting at indexoff
.void
readFully(int[] i, int off, int len)
Readslen
ints (signed 32-bit integers) from the stream according to the current byte order, and stores them intoi
starting at indexoff
.void
readFully(long[] l, int off, int len)
Readslen
longs (signed 64-bit integers) from the stream according to the current byte order, and stores them intol
starting at indexoff
.void
readFully(short[] s, int off, int len)
Readslen
shorts (signed 16-bit integers) from the stream according to the current byte order, and stores them intos
starting at indexoff
.int
readInt()
Reads 4 bytes from the stream, and (conceptually) concatenates them according to the current byte order and returns the result as anint
.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 along
.short
readShort()
Reads two bytes from the stream, and (conceptually) concatenates them according to the current byte order, and returns the result as ashort
value.int
readUnsignedByte()
Reads a byte from the stream, and (conceptually) converts it to an int, masks it with0xff
in order to strip off any sign-extension bits, and returns it as abyte
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 with0xffffffffL
in order to strip off any sign-extension bits, and returns the result as an unsignedlong
value.int
readUnsignedShort()
Reads two bytes from the stream, and (conceptually) concatenates them according to the current byte order, converts the resulting value to anint
, masks it with0xffff
in order to strip off any sign-extension buts, and returns the result as an unsignedint
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 callingseek(getStreamPosition() + n)
.long
skipBytes(long n)
Advances the current stream position by callingseek(getStreamPosition() + n)
.
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Field Detail
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byteOrder
protected ByteOrder byteOrder
The byte order of the stream as an instance of the enumeration classjava.nio.ByteOrder
, whereByteOrder.BIG_ENDIAN
indicates network byte order andByteOrder.LITTLE_ENDIAN
indicates the reverse order. By default, the value isByteOrder.BIG_ENDIAN
.
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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.
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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.
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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.
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Constructor Detail
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ImageInputStreamImpl
public ImageInputStreamImpl()
Constructs anImageInputStreamImpl
.
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Method Detail
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checkClosed
protected final void checkClosed() throws IOException
Throws anIOException
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.
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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 ofByteOrder.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 reverseByteOrder.LITTLE_ENDIAN
order.The byte order has no effect on the results returned from the
readBits
method (or the value written byImageOutputStream.writeBits
).- Specified by:
setByteOrder
in interfaceImageInputStream
- Parameters:
byteOrder
- one ofByteOrder.BIG_ENDIAN
orjava.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)
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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 thejava.nio.ByteOrder
enumeration.- Specified by:
getByteOrder
in interfaceImageInputStream
- Returns:
- one of
ByteOrder.BIG_ENDIAN
orByteOrder.LITTLE_ENDIAN
, indicating which byte order is being used. - See Also:
ByteOrder
,ImageInputStream.setByteOrder(java.nio.ByteOrder)
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read
public abstract int read() throws IOException
Reads a single byte from the stream and returns it as anint
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.
- Specified by:
read
in interfaceImageInputStream
- Returns:
- the value of the next byte in the stream, or
-1
if EOF is reached. - Throws:
IOException
- if the stream has been closed.
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read
public int read(byte[] b) throws IOException
A convenience method that callsread(b, 0, b.length)
.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
read
in interfaceImageInputStream
- Parameters:
b
- an array of bytes to be written to.- Returns:
- the number of bytes actually read, or
-1
to indicate EOF. - Throws:
NullPointerException
- ifb
isnull
.IOException
- if an I/O error occurs.
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read
public abstract int read(byte[] b, int off, int len) throws IOException
Reads up tolen
bytes from the stream, and stores them intob
starting at indexoff
. 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 interfaceImageInputStream
- Parameters:
b
- an array of bytes to be written to.off
- the starting position withinb
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
- ifoff
is negative,len
is negative, oroff + len
is greater thanb.length
.NullPointerException
- ifb
isnull
.IOException
- if an I/O error occurs.
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readBytes
public void readBytes(IIOByteBuffer buf, int len) throws IOException
Description copied from interface:ImageInputStream
Reads up tolen
bytes from the stream, and modifies the suppliedIIOByteBuffer
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 theIIOByteBuffer
.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readBytes
in interfaceImageInputStream
- Parameters:
buf
- an IIOByteBuffer object to be modified.len
- the maximum number ofbyte
s to read.- Throws:
IOException
- if an I/O error occurs.
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readBoolean
public boolean readBoolean() throws IOException
Description copied from interface:ImageInputStream
Reads a byte from the stream and returns aboolean
value oftrue
if it is nonzero,false
if it is zero.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readBoolean
in interfaceDataInput
- Specified by:
readBoolean
in interfaceImageInputStream
- Returns:
- a boolean value from the stream.
- Throws:
IOException
- if an I/O error occurs.
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readByte
public byte readByte() throws IOException
Description copied from interface:ImageInputStream
Reads a byte from the stream and returns it as abyte
value. Byte values between0x00
and0x7f
represent integer values between0
and127
. Values between0x80
and0xff
represent negative values from-128
to/1
.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readByte
in interfaceDataInput
- Specified by:
readByte
in interfaceImageInputStream
- Returns:
- a signed byte value from the stream.
- Throws:
IOException
- if an I/O error occurs.
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readUnsignedByte
public int readUnsignedByte() throws IOException
Description copied from interface:ImageInputStream
Reads a byte from the stream, and (conceptually) converts it to an int, masks it with0xff
in order to strip off any sign-extension bits, and returns it as abyte
value.Thus, byte values between
0x00
and0x7f
are simply returned as integer values between0
and127
. Values between0x80
and0xff
, which normally represent negativebyte
values, will be mapped into positive integers between128
and255
.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readUnsignedByte
in interfaceDataInput
- Specified by:
readUnsignedByte
in interfaceImageInputStream
- Returns:
- an unsigned byte value from the stream.
- Throws:
IOException
- if an I/O error occurs.
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readShort
public short readShort() throws IOException
Description copied from interface:ImageInputStream
Reads two bytes from the stream, and (conceptually) concatenates them according to the current byte order, and returns the result as ashort
value.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readShort
in interfaceDataInput
- Specified by:
readShort
in interfaceImageInputStream
- Returns:
- a signed short value from the stream.
- Throws:
IOException
- if an I/O error occurs.- See Also:
ImageInputStream.getByteOrder()
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readUnsignedShort
public int readUnsignedShort() throws IOException
Description copied from interface:ImageInputStream
Reads two bytes from the stream, and (conceptually) concatenates them according to the current byte order, converts the resulting value to anint
, masks it with0xffff
in order to strip off any sign-extension buts, and returns the result as an unsignedint
value.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readUnsignedShort
in interfaceDataInput
- Specified by:
readUnsignedShort
in interfaceImageInputStream
- Returns:
- an unsigned short value from the stream, as an int.
- Throws:
IOException
- if an I/O error occurs.- See Also:
ImageInputStream.getByteOrder()
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readChar
public char readChar() throws IOException
Description copied from interface:ImageInputStream
Equivalent toreadUnsignedShort
, except that the result is returned using thechar
datatype.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readChar
in interfaceDataInput
- Specified by:
readChar
in interfaceImageInputStream
- Returns:
- an unsigned char value from the stream.
- Throws:
IOException
- if an I/O error occurs.- See Also:
ImageInputStream.readUnsignedShort()
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readInt
public int readInt() throws IOException
Description copied from interface:ImageInputStream
Reads 4 bytes from the stream, and (conceptually) concatenates them according to the current byte order and returns the result as anint
.The bit offset within the stream is ignored and treated as though it were zero.
- Specified by:
readInt
in interfaceDataInput
- Specified by:
readInt
in interfaceImageInputStream
- Returns:
- a signed int value from the stream.
- Throws:
IOException
- if an I/O error occurs.- See Also:
ImageInputStream.getByteOrder()
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readUnsignedInt
public long readUnsignedInt() throws IOException
Description copied from interface:ImageInputStream
Reads 4 bytes from the stream, and (conceptually) concatenates them according to the current byte order, converts the result to a long, masks it with0xffffffffL
in order to strip off any sign-extension bits, and returns the result as an unsignedlong
value.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readUnsignedInt
in interfaceImageInputStream
- Returns:
- an unsigned int value from the stream, as a long.
- Throws:
IOException
- if an I/O error occurs.- See Also:
ImageInputStream.getByteOrder()
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readLong
public long readLong() throws IOException
Description copied from interface:ImageInputStream
Reads 8 bytes from the stream, and (conceptually) concatenates them according to the current byte order and returns the result as along
.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readLong
in interfaceDataInput
- Specified by:
readLong
in interfaceImageInputStream
- Returns:
- a signed long value from the stream.
- Throws:
IOException
- if an I/O error occurs.- See Also:
ImageInputStream.getByteOrder()
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readFloat
public float readFloat() throws IOException
Description copied from interface:ImageInputStream
Reads 4 bytes from the stream, and (conceptually) concatenates them according to the current byte order and returns the result as afloat
.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readFloat
in interfaceDataInput
- Specified by:
readFloat
in interfaceImageInputStream
- Returns:
- a float value from the stream.
- Throws:
IOException
- if an I/O error occurs.- See Also:
ImageInputStream.getByteOrder()
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readDouble
public double readDouble() throws IOException
Description copied from interface:ImageInputStream
Reads 8 bytes from the stream, and (conceptually) concatenates them according to the current byte order and returns the result as adouble
.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readDouble
in interfaceDataInput
- Specified by:
readDouble
in interfaceImageInputStream
- Returns:
- a double value from the stream.
- Throws:
IOException
- if an I/O error occurs.- See Also:
ImageInputStream.getByteOrder()
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readLine
public String readLine() throws IOException
Description copied from interface:ImageInputStream
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 aString
. 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 typechar
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, aString
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.
- Specified by:
readLine
in interfaceDataInput
- Specified by:
readLine
in interfaceImageInputStream
- Returns:
- a String containing a line of text from the stream.
- Throws:
IOException
- if an I/O error occurs.
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readUTF
public String readUTF() throws IOException
Description copied from interface:ImageInputStream
Reads in a string that has been encoded using a modified UTF-8 format. The general contract ofreadUTF
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 aString
.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
(wherex
means "may be0
or1
"), 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 bytea
and a second byteb
. If there is no byteb
(because bytea
was the last of the bytes to be read), or if byteb
does not match the bit pattern10xxxxxx
, then aUTFDataFormatException
is thrown. Otherwise, the group is converted to the character:
If the first byte of a group matches the bit pattern(char)(((a& 0x1F) << 6) | (b & 0x3F))
1110xxxx
, then the group consists of that bytea
and two more bytesb
andc
. If there is no bytec
(because bytea
was one of the last two of the bytes to be read), or either byteb
or bytec
does not match the bit pattern10xxxxxx
, then aUTFDataFormatException
is thrown. Otherwise, the group is converted to the character:
If the first byte of a group matches the pattern(char)(((a & 0x0F) << 12) | ((b & 0x3F) << 6) | (c & 0x3F))
1111xxxx
or the pattern10xxxxxx
, then aUTFDataFormatException
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.
- Specified by:
readUTF
in interfaceDataInput
- Specified by:
readUTF
in interfaceImageInputStream
- Returns:
- a String read from the stream.
- Throws:
IOException
- if an I/O error occurs.
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readFully
public void readFully(byte[] b, int off, int len) throws IOException
Description copied from interface:ImageInputStream
Readslen
bytes from the stream, and stores them intob
starting at indexoff
. If the end of the stream is reached, anEOFException
will be thrown.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readFully
in interfaceDataInput
- Specified by:
readFully
in interfaceImageInputStream
- Parameters:
b
- an array of bytes to be written to.off
- the starting position withinb
to write to.len
- the maximum number ofbyte
s to read.- Throws:
IOException
- if an I/O error occurs.
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readFully
public void readFully(byte[] b) throws IOException
Description copied from interface:ImageInputStream
Readsb.length
bytes from the stream, and stores them intob
starting at index0
. If the end of the stream is reached, anEOFException
will be thrown.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readFully
in interfaceDataInput
- Specified by:
readFully
in interfaceImageInputStream
- Parameters:
b
- an array ofbyte
s.- Throws:
IOException
- if an I/O error occurs.
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readFully
public void readFully(short[] s, int off, int len) throws IOException
Description copied from interface:ImageInputStream
Readslen
shorts (signed 16-bit integers) from the stream according to the current byte order, and stores them intos
starting at indexoff
. If the end of the stream is reached, anEOFException
will be thrown.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readFully
in interfaceImageInputStream
- Parameters:
s
- an array of shorts to be written to.off
- the starting position withinb to write to.len
- the maximum number ofshort
s to read.- Throws:
IOException
- if an I/O error occurs.
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readFully
public void readFully(char[] c, int off, int len) throws IOException
Description copied from interface:ImageInputStream
Readslen
chars (unsigned 16-bit integers) from the stream according to the current byte order, and stores them intoc
starting at indexoff
. If the end of the stream is reached, anEOFException
will be thrown.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readFully
in interfaceImageInputStream
- Parameters:
c
- an array of chars to be written to.off
- the starting position withinb to write to.len
- the maximum number ofchar
s to read.- Throws:
IOException
- if an I/O error occurs.
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readFully
public void readFully(int[] i, int off, int len) throws IOException
Description copied from interface:ImageInputStream
Readslen
ints (signed 32-bit integers) from the stream according to the current byte order, and stores them intoi
starting at indexoff
. If the end of the stream is reached, anEOFException
will be thrown.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readFully
in interfaceImageInputStream
- Parameters:
i
- an array of ints to be written to.off
- the starting position withinb to write to.len
- the maximum number ofint
s to read.- Throws:
IOException
- if an I/O error occurs.
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readFully
public void readFully(long[] l, int off, int len) throws IOException
Description copied from interface:ImageInputStream
Readslen
longs (signed 64-bit integers) from the stream according to the current byte order, and stores them intol
starting at indexoff
. If the end of the stream is reached, anEOFException
will be thrown.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readFully
in interfaceImageInputStream
- Parameters:
l
- an array of longs to be written to.off
- the starting position withinb to write to.len
- the maximum number oflong
s to read.- Throws:
IOException
- if an I/O error occurs.
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readFully
public void readFully(float[] f, int off, int len) throws IOException
Description copied from interface:ImageInputStream
Readslen
floats (32-bit IEEE single-precision floats) from the stream according to the current byte order, and stores them intof
starting at indexoff
. If the end of the stream is reached, anEOFException
will be thrown.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readFully
in interfaceImageInputStream
- Parameters:
f
- an array of floats to be written to.off
- the starting position withinb to write to.len
- the maximum number offloat
s to read.- Throws:
IOException
- if an I/O error occurs.
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readFully
public void readFully(double[] d, int off, int len) throws IOException
Description copied from interface:ImageInputStream
Readslen
doubles (64-bit IEEE double-precision floats) from the stream according to the current byte order, and stores them intod
starting at indexoff
. If the end of the stream is reached, anEOFException
will be thrown.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readFully
in interfaceImageInputStream
- Parameters:
d
- an array of doubles to be written to.off
- the starting position withinb to write to.len
- the maximum number ofdouble
s to read.- Throws:
IOException
- if an I/O error occurs.
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getStreamPosition
public long getStreamPosition() throws IOException
Description copied from interface:ImageInputStream
Returns the current byte position of the stream. The next read will take place starting at this offset.- Specified by:
getStreamPosition
in interfaceImageInputStream
- Returns:
- a long containing the position of the stream.
- Throws:
IOException
- if an I/O error occurs.
-
getBitOffset
public int getBitOffset() throws IOException
Description copied from interface:ImageInputStream
Returns the current bit offset, as an integer between 0 and 7, inclusive. The bit offset is updated implicitly by calls to thereadBits
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 anyread
orreadFully
method.- Specified by:
getBitOffset
in interfaceImageInputStream
- Returns:
- an
int
containing the bit offset between 0 and 7, inclusive. - Throws:
IOException
- if an I/O error occurs.- See Also:
ImageInputStream.setBitOffset(int)
-
setBitOffset
public void setBitOffset(int bitOffset) throws IOException
Description copied from interface:ImageInputStream
Sets the bit offset to an integer between 0 and 7, inclusive. The byte offset within the stream, as returned bygetStreamPosition
, 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.- Specified by:
setBitOffset
in interfaceImageInputStream
- Parameters:
bitOffset
- the desired offset, as anint
between 0 and 7, inclusive.- Throws:
IOException
- if an I/O error occurs.- See Also:
ImageInputStream.getBitOffset()
-
readBit
public int readBit() throws IOException
Description copied from interface:ImageInputStream
Reads a single bit from the stream and returns it as anint
with the value0
or1
. The bit offset is advanced by one and reduced modulo 8.- Specified by:
readBit
in interfaceImageInputStream
- Returns:
- an
int
containing the value0
or1
. - Throws:
IOException
- if an I/O error occurs.
-
readBits
public long readBits(int numBits) throws IOException
Description copied from interface:ImageInputStream
Reads a bitstring from the stream and returns it as along
, with the first bit read becoming the most significant bit of the output. The read starts within the byte indicated bygetStreamPosition
, at the bit given bygetBitOffset
. The bit offset is advanced bynumBits
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 ofreadBits(32)
may thus not be equal to that ofreadInt()
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.- Specified by:
readBits
in interfaceImageInputStream
- Parameters:
numBits
- the number of bits to read, as anint
between 0 and 64, inclusive.- Returns:
- the bitstring, as a
long
with the last bit read stored in the least significant bit. - Throws:
IOException
- if an I/O error occurs.
-
length
public long length()
Returns-1L
to indicate that the stream has unknown length. Subclasses must override this method to provide actual length information.- Specified by:
length
in interfaceImageInputStream
- Returns:
- -1L to indicate unknown length.
-
skipBytes
public int skipBytes(int n) throws IOException
Advances the current stream position by callingseek(getStreamPosition() + n)
.The bit offset is reset to zero.
- Specified by:
skipBytes
in interfaceDataInput
- Specified by:
skipBytes
in interfaceImageInputStream
- Parameters:
n
- the number of bytes to seek forward.- Returns:
- an
int
representing the number of bytes skipped. - Throws:
IOException
- ifgetStreamPosition
throws anIOException
when computing either the starting or ending position.
-
skipBytes
public long skipBytes(long n) throws IOException
Advances the current stream position by callingseek(getStreamPosition() + n)
.The bit offset is reset to zero.
- Specified by:
skipBytes
in interfaceImageInputStream
- Parameters:
n
- the number of bytes to seek forward.- Returns:
- a
long
representing the number of bytes skipped. - Throws:
IOException
- ifgetStreamPosition
throws anIOException
when computing either the starting or ending position.
-
seek
public void seek(long pos) throws IOException
Description copied from interface:ImageInputStream
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 ifpos
is smaller than the flushed position (as returned bygetflushedPosition
).It is legal to seek past the end of the file; an
EOFException
will be thrown only if a read is performed.- Specified by:
seek
in interfaceImageInputStream
- Parameters:
pos
- along
containing the desired file pointer position.- Throws:
IOException
- if any other I/O error occurs.
-
mark
public void mark()
Pushes the current stream position onto a stack of marked positions.- Specified by:
mark
in interfaceImageInputStream
-
reset
public void reset() throws IOException
Resets the current stream byte and bit positions from the stack of marked positions.An
IOException
will be thrown if the previous marked position lies in the discarded portion of the stream.- Specified by:
reset
in interfaceImageInputStream
- Throws:
IOException
- if an I/O error occurs.
-
flushBefore
public void flushBefore(long pos) throws IOException
Description copied from interface:ImageInputStream
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 anIndexOutOfBoundsException
.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.- Specified by:
flushBefore
in interfaceImageInputStream
- Parameters:
pos
- along
containing the length of the stream prefix that may be flushed.- Throws:
IOException
- if an I/O error occurs.
-
flush
public void flush() throws IOException
Description copied from interface:ImageInputStream
Discards the initial position of the stream prior to the current stream position. Equivalent toflushBefore(getStreamPosition())
.- Specified by:
flush
in interfaceImageInputStream
- Throws:
IOException
- if an I/O error occurs.
-
getFlushedPosition
public long getFlushedPosition()
Description copied from interface:ImageInputStream
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 toflushBefore
.- Specified by:
getFlushedPosition
in interfaceImageInputStream
- Returns:
- the earliest legal position for seeking, as a
long
.
-
isCached
public boolean isCached()
Default implementation returns false. Subclasses should override this if they cache data.- Specified by:
isCached
in interfaceImageInputStream
- Returns:
true
if thisImageInputStream
caches data.- See Also:
ImageInputStream.isCachedMemory()
,ImageInputStream.isCachedFile()
-
isCachedMemory
public boolean isCachedMemory()
Default implementation returns false. Subclasses should override this if they cache data in main memory.- Specified by:
isCachedMemory
in interfaceImageInputStream
- Returns:
true
if thisImageInputStream
caches data in main memory.- See Also:
ImageInputStream.isCached()
,ImageInputStream.isCachedFile()
-
isCachedFile
public boolean isCachedFile()
Default implementation returns false. Subclasses should override this if they cache data in a temporary file.- Specified by:
isCachedFile
in interfaceImageInputStream
- Returns:
true
if thisImageInputStream
caches data in a temporary file.- See Also:
ImageInputStream.isCached()
,ImageInputStream.isCachedMemory()
-
close
public void close() throws IOException
Description copied from interface:ImageInputStream
Closes the stream. Attempts to access a stream that has been closed may result inIOException
s 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.- Specified by:
close
in interfaceCloseable
- Specified by:
close
in interfaceAutoCloseable
- Specified by:
close
in interfaceImageInputStream
- Throws:
IOException
- if an I/O error occurs.
-
finalize
protected void finalize() throws Throwable
Finalizes this object prior to garbage collection. Theclose
method is called to close any open input source. This method should not be called from application code.
-
-
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Dokument erstellt 11/06/2005, zuletzt geändert 04/03/2020
Quelle des gedruckten Dokuments:https://www.gaudry.be/de/java-api-rf-javax/imageio/stream/ImageInputStreamImpl.html
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