Interface ImageInputStream
- All Superinterfaces:
AutoCloseable,Closeable,DataInput
- All Known Subinterfaces:
ImageOutputStream
- All Known Implementing Classes:
FileCacheImageInputStream,FileCacheImageOutputStream,FileImageInputStream,FileImageOutputStream,ImageInputStreamImpl,ImageOutputStreamImpl,MemoryCacheImageInputStream,MemoryCacheImageOutputStream
ImageReaders. Various input sources, such as
InputStreams and Files,
as well as future fast I/O sources may be "wrapped" by a suitable
implementation of this interface for use by the Image I/O API.- See Also:
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Method Summary
Modifier and TypeMethodDescriptionvoidclose()Closes the stream.voidflush()Discards the initial position of the stream prior to the current stream position.voidflushBefore(long pos) Discards the initial portion of the stream prior to the indicated position.intReturns the current bit offset, as an integer between 0 and 7, inclusive.Returns the byte order with which data values will be read from this stream as an instance of thejava.nio.ByteOrderenumeration.longReturns the earliest position in the stream to which seeking may be performed.longReturns the current byte position of the stream.booleanisCached()Returnstrueif thisImageInputStreamcaches data itself in order to allow seeking backwards.booleanReturnstrueif thisImageInputStreamcaches data itself in order to allow seeking backwards, and the cache is kept in a temporary file.booleanReturnstrueif thisImageInputStreamcaches data itself in order to allow seeking backwards, and the cache is kept in main memory.longlength()Returns the total length of the stream, if known.voidmark()Marks a position in the stream to be returned to by a subsequent call toreset.intread()Reads a single byte from the stream and returns it as an integer between 0 and 255.intread(byte[] b) Reads up tob.lengthbytes from the stream, and stores them intobstarting at index 0.intread(byte[] b, int off, int len) Reads up tolenbytes from the stream, and stores them intobstarting at indexoff.intreadBit()Reads a single bit from the stream and returns it as anintwith the value0or1.longreadBits(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.booleanReads a byte from the stream and returns abooleanvalue oftrueif it is nonzero,falseif it is zero.bytereadByte()Reads a byte from the stream and returns it as abytevalue.voidreadBytes(IIOByteBuffer buf, int len) Reads up tolenbytes from the stream, and modifies the suppliedIIOByteBufferto indicate the byte array, offset, and length where the data may be found.charreadChar()Equivalent toreadUnsignedShort, except that the result is returned using thechardatatype.doubleReads 8 bytes from the stream, and (conceptually) concatenates them according to the current byte order and returns the result as adouble.floatReads 4 bytes from the stream, and (conceptually) concatenates them according to the current byte order and returns the result as afloat.voidreadFully(byte[] b) Readsb.lengthbytes from the stream, and stores them intobstarting at index0.voidreadFully(byte[] b, int off, int len) Readslenbytes from the stream, and stores them intobstarting at indexoff.voidreadFully(char[] c, int off, int len) Readslenchars (unsigned 16-bit integers) from the stream according to the current byte order, and stores them intocstarting at indexoff.voidreadFully(double[] d, int off, int len) Readslendoubles (64-bit IEEE double-precision floats) from the stream according to the current byte order, and stores them intodstarting at indexoff.voidreadFully(float[] f, int off, int len) Readslenfloats (32-bit IEEE single-precision floats) from the stream according to the current byte order, and stores them intofstarting at indexoff.voidreadFully(int[] i, int off, int len) Readslenints (signed 32-bit integers) from the stream according to the current byte order, and stores them intoistarting at indexoff.voidreadFully(long[] l, int off, int len) Readslenlongs (signed 64-bit integers) from the stream according to the current byte order, and stores them intolstarting at indexoff.voidreadFully(short[] s, int off, int len) Readslenshorts (signed 16-bit integers) from the stream according to the current byte order, and stores them intosstarting at indexoff.intreadInt()Reads 4 bytes from the stream, and (conceptually) concatenates them according to the current byte order and returns the result as anint.readLine()Reads the next line of text from the input stream.longreadLong()Reads 8 bytes from the stream, and (conceptually) concatenates them according to the current byte order and returns the result as along.shortReads two bytes from the stream, and (conceptually) concatenates them according to the current byte order, and returns the result as ashortvalue.intReads a byte from the stream, and (conceptually) converts it to an int, masks it with0xffin order to strip off any sign-extension bits, and returns it as abytevalue.longReads 4 bytes from the stream, and (conceptually) concatenates them according to the current byte order, converts the result to a long, masks it with0xffffffffLin order to strip off any sign-extension bits, and returns the result as an unsignedlongvalue.intReads two bytes from the stream, and (conceptually) concatenates them according to the current byte order, converts the resulting value to anint, masks it with0xffffin order to strip off any sign-extension buts, and returns the result as an unsignedintvalue.readUTF()Reads in a string that has been encoded using a modified UTF-8 format.voidreset()Returns the stream pointer to its previous position, including the bit offset, at the time of the most recent unmatched call tomark.voidseek(long pos) Sets the current stream position to the desired location.voidsetBitOffset(int bitOffset) Sets the bit offset to an integer between 0 and 7, inclusive.voidsetByteOrder(ByteOrder byteOrder) Sets the desired byte order for future reads of data values from this stream.intskipBytes(int n) Moves the stream position forward by a given number of bytes.longskipBytes(long n) Moves the stream position forward by a given number of bytes.
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Method Details
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setByteOrder
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.ByteOrderis used to specify the byte order. A value ofByteOrder.BIG_ENDIANspecifies 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_ENDIANorder.The byte order has no effect on the results returned from the
readBitsmethod (or the value written byImageOutputStream.writeBits).- Parameters:
byteOrder- one ofByteOrder.BIG_ENDIANorjava.nio.ByteOrder.LITTLE_ENDIAN, indicating whether network byte order or its reverse will be used for future reads.- See Also:
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getByteOrder
ByteOrder getByteOrder()Returns the byte order with which data values will be read from this stream as an instance of thejava.nio.ByteOrderenumeration.- Returns:
- one of
ByteOrder.BIG_ENDIANorByteOrder.LITTLE_ENDIAN, indicating which byte order is being used. - See Also:
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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.
- Returns:
- a byte value from the stream, as an int, or -1 to indicate EOF.
- Throws:
IOException- if an I/O error occurs.
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read
Reads up tob.lengthbytes from the stream, and stores them intobstarting 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.
- Parameters:
b- an array of bytes to be written to.- Returns:
- the number of bytes actually read, or
-1to indicate EOF. - Throws:
NullPointerException- ifbisnull.IOException- if an I/O error occurs.
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read
Reads up tolenbytes from the stream, and stores them intobstarting at indexoff. The number of bytes read is returned. If no bytes can be read because the end of the stream has been reached,-1is returned.The bit offset within the stream is reset to zero before the read occurs.
- Parameters:
b- an array of bytes to be written to.off- the starting position withinbto write to.len- the maximum number ofbytes to read.- Returns:
- the number of bytes actually read, or
-1to indicate EOF. - Throws:
NullPointerException- ifbisnull.IndexOutOfBoundsException- ifoffis negative,lenis negative, oroff + lenis greater thanb.length.IOException- if an I/O error occurs.
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readBytes
Reads up tolenbytes from the stream, and modifies the suppliedIIOByteBufferto 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.
- Parameters:
buf- an IIOByteBuffer object to be modified.len- the maximum number ofbytes to read.- Throws:
IndexOutOfBoundsException- iflenis negative.NullPointerException- ifbufisnull.IOException- if an I/O error occurs.
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readBoolean
Reads a byte from the stream and returns abooleanvalue oftrueif it is nonzero,falseif it is zero.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readBooleanin interfaceDataInput- Returns:
- a boolean value from the stream.
- Throws:
EOFException- if the end of the stream is reached.IOException- if an I/O error occurs.
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readByte
Reads a byte from the stream and returns it as abytevalue. Byte values between0x00and0x7frepresent integer values between0and127. Values between0x80and0xffrepresent negative values from-128to/1.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readBytein interfaceDataInput- Returns:
- a signed byte value from the stream.
- Throws:
EOFException- if the end of the stream is reached.IOException- if an I/O error occurs.
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readUnsignedByte
Reads a byte from the stream, and (conceptually) converts it to an int, masks it with0xffin order to strip off any sign-extension bits, and returns it as abytevalue.Thus, byte values between
0x00and0x7fare simply returned as integer values between0and127. Values between0x80and0xff, which normally represent negativebytevalues, will be mapped into positive integers between128and255.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readUnsignedBytein interfaceDataInput- Returns:
- an unsigned byte value from the stream.
- Throws:
EOFException- if the end of the stream is reached.IOException- if an I/O error occurs.
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readShort
Reads two bytes from the stream, and (conceptually) concatenates them according to the current byte order, and returns the result as ashortvalue.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readShortin interfaceDataInput- Returns:
- a signed short value from the stream.
- Throws:
EOFException- if the stream reaches the end before reading all the bytes.IOException- if an I/O error occurs.- See Also:
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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 with0xffffin order to strip off any sign-extension buts, and returns the result as an unsignedintvalue.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readUnsignedShortin interfaceDataInput- Returns:
- an unsigned short value from the stream, as an int.
- Throws:
EOFException- if the stream reaches the end before reading all the bytes.IOException- if an I/O error occurs.- See Also:
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readChar
Equivalent toreadUnsignedShort, except that the result is returned using thechardatatype.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readCharin interfaceDataInput- Returns:
- an unsigned char value from the stream.
- Throws:
EOFException- if the stream reaches the end before reading all the bytes.IOException- if an I/O error occurs.- See Also:
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readInt
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:
readIntin interfaceDataInput- Returns:
- a signed int value from the stream.
- Throws:
EOFException- if the stream reaches the end before reading all the bytes.IOException- if an I/O error occurs.- See Also:
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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 with0xffffffffLin order to strip off any sign-extension bits, and returns the result as an unsignedlongvalue.The bit offset within the stream is reset to zero before the read occurs.
- Returns:
- an unsigned int value from the stream, as a long.
- Throws:
EOFException- if the stream reaches the end before reading all the bytes.IOException- if an I/O error occurs.- See Also:
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readLong
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:
readLongin interfaceDataInput- Returns:
- a signed long value from the stream.
- Throws:
EOFException- if the stream reaches the end before reading all the bytes.IOException- if an I/O error occurs.- See Also:
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readFloat
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:
readFloatin interfaceDataInput- Returns:
- a float value from the stream.
- Throws:
EOFException- if the stream reaches the end before reading all the bytes.IOException- if an I/O error occurs.- See Also:
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readDouble
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:
readDoublein interfaceDataInput- Returns:
- a double value from the stream.
- Throws:
EOFException- if the stream reaches the end before reading all the bytes.IOException- if an I/O error occurs.- See Also:
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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 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
nullis returned. Otherwise, each byte that is read is converted to typecharby 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, aStringis 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:
readLinein interfaceDataInput- Returns:
- a String containing a line of text from the stream.
- Throws:
IOException- if an I/O error occurs.
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readUTF
Reads in a string that has been encoded using a modified UTF-8 format. The general contract ofreadUTFis 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
readUnsignedShortmethod, 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(wherexmeans "may be0or1"), 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 byteaand a second byteb. If there is no byteb(because byteawas the last of the bytes to be read), or if bytebdoes not match the bit pattern10xxxxxx, then aUTFDataFormatExceptionis 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 byteaand two more bytesbandc. If there is no bytec(because byteawas one of the last two of the bytes to be read), or either bytebor bytecdoes not match the bit pattern10xxxxxx, then aUTFDataFormatExceptionis 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))1111xxxxor the pattern10xxxxxx, then aUTFDataFormatExceptionis thrown.If end of file is encountered at any time during this entire process, then a
java.io.EOFExceptionis 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:
readUTFin interfaceDataInput- Returns:
- a String read from the stream.
- Throws:
EOFException- if this stream reaches the end before reading all the bytes.UTFDataFormatException- if the bytes do not represent a valid modified UTF-8 encoding of a string.IOException- if an I/O error occurs.
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readFully
Readslenbytes from the stream, and stores them intobstarting at indexoff. If the end of the stream is reached, ajava.io.EOFExceptionwill be thrown.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readFullyin interfaceDataInput- Parameters:
b- an array of bytes to be written to.off- the starting position withinbto write to.len- the maximum number ofbytes to read.- Throws:
IndexOutOfBoundsException- ifoffis negative,lenis negative, oroff + lenis greater thanb.length.NullPointerException- ifbisnull.EOFException- if the stream reaches the end before reading all the bytes.IOException- if an I/O error occurs.
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readFully
Readsb.lengthbytes from the stream, and stores them intobstarting at index0. If the end of the stream is reached, ajava.io.EOFExceptionwill be thrown.The bit offset within the stream is reset to zero before the read occurs.
- Specified by:
readFullyin interfaceDataInput- Parameters:
b- an array ofbytes.- Throws:
NullPointerException- ifbisnull.EOFException- if the stream reaches the end before reading all the bytes.IOException- if an I/O error occurs.
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readFully
Readslenshorts (signed 16-bit integers) from the stream according to the current byte order, and stores them intosstarting at indexoff. If the end of the stream is reached, ajava.io.EOFExceptionwill be thrown.The bit offset within the stream is reset to zero before the read occurs.
- Parameters:
s- an array of shorts to be written to.off- the starting position withinsto write to.len- the maximum number ofshorts to read.- Throws:
IndexOutOfBoundsException- ifoffis negative,lenis negative, oroff + lenis greater thans.length.NullPointerException- ifsisnull.EOFException- if the stream reaches the end before reading all the bytes.IOException- if an I/O error occurs.
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readFully
Readslenchars (unsigned 16-bit integers) from the stream according to the current byte order, and stores them intocstarting at indexoff. If the end of the stream is reached, ajava.io.EOFExceptionwill be thrown.The bit offset within the stream is reset to zero before the read occurs.
- Parameters:
c- an array of chars to be written to.off- the starting position withincto write to.len- the maximum number ofchars to read.- Throws:
IndexOutOfBoundsException- ifoffis negative,lenis negative, oroff + lenis greater thanc.length.NullPointerException- ifcisnull.EOFException- if the stream reaches the end before reading all the bytes.IOException- if an I/O error occurs.
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readFully
Readslenints (signed 32-bit integers) from the stream according to the current byte order, and stores them intoistarting at indexoff. If the end of the stream is reached, ajava.io.EOFExceptionwill be thrown.The bit offset within the stream is reset to zero before the read occurs.
- Parameters:
i- an array of ints to be written to.off- the starting position withinito write to.len- the maximum number ofints to read.- Throws:
IndexOutOfBoundsException- ifoffis negative,lenis negative, oroff + lenis greater thani.length.NullPointerException- ifiisnull.EOFException- if the stream reaches the end before reading all the bytes.IOException- if an I/O error occurs.
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readFully
Readslenlongs (signed 64-bit integers) from the stream according to the current byte order, and stores them intolstarting at indexoff. If the end of the stream is reached, ajava.io.EOFExceptionwill be thrown.The bit offset within the stream is reset to zero before the read occurs.
- Parameters:
l- an array of longs to be written to.off- the starting position withinlto write to.len- the maximum number oflongs to read.- Throws:
IndexOutOfBoundsException- ifoffis negative,lenis negative, oroff + lenis greater thanl.length.NullPointerException- iflisnull.EOFException- if the stream reaches the end before reading all the bytes.IOException- if an I/O error occurs.
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readFully
Readslenfloats (32-bit IEEE single-precision floats) from the stream according to the current byte order, and stores them intofstarting at indexoff. If the end of the stream is reached, ajava.io.EOFExceptionwill be thrown.The bit offset within the stream is reset to zero before the read occurs.
- Parameters:
f- an array of floats to be written to.off- the starting position withinfto write to.len- the maximum number offloats to read.- Throws:
IndexOutOfBoundsException- ifoffis negative,lenis negative, oroff + lenis greater thanf.length.NullPointerException- iffisnull.EOFException- if the stream reaches the end before reading all the bytes.IOException- if an I/O error occurs.
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readFully
Readslendoubles (64-bit IEEE double-precision floats) from the stream according to the current byte order, and stores them intodstarting at indexoff. If the end of the stream is reached, ajava.io.EOFExceptionwill be thrown.The bit offset within the stream is reset to zero before the read occurs.
- Parameters:
d- an array of doubles to be written to.off- the starting position withindto write to.len- the maximum number ofdoubles to read.- Throws:
IndexOutOfBoundsException- ifoffis negative,lenis negative, oroff + lenis greater thand.length.NullPointerException- ifdisnull.EOFException- if the stream reaches the end before reading all the bytes.IOException- if an I/O error occurs.
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getStreamPosition
Returns the current byte position of the stream. The next read will take place starting at this offset.- Returns:
- a long containing the position of the stream.
- Throws:
IOException- if an I/O error occurs.
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getBitOffset
Returns the current bit offset, as an integer between 0 and 7, inclusive. The bit offset is updated implicitly by calls to thereadBitsmethod. 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 anyreadorreadFullymethod.- Returns:
- an
intcontaining the bit offset between 0 and 7, inclusive. - Throws:
IOException- if an I/O error occurs.- See Also:
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setBitOffset
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.- Parameters:
bitOffset- the desired offset, as anintbetween 0 and 7, inclusive.- Throws:
IllegalArgumentException- ifbitOffsetis not between 0 and 7, inclusive.IOException- if an I/O error occurs.- See Also:
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readBit
Reads a single bit from the stream and returns it as anintwith the value0or1. The bit offset is advanced by one and reduced modulo 8.- Returns:
- an
intcontaining the value0or1. - Throws:
EOFException- if the stream reaches the end before reading all the bits.IOException- if an I/O error occurs.
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readBits
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 bynumBitsand 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:
Note that the result oflong accum = 0L; for (int i = 0; i < numBits; i++) { accum <<= 1; // Shift left one bit to make room accum |= readBit(); }readBits(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, a
java.io.EOFExceptionis thrown.- Parameters:
numBits- the number of bits to read, as anintbetween 0 and 64, inclusive.- Returns:
- the bitstring, as a
longwith the last bit read stored in the least significant bit. - Throws:
IllegalArgumentException- ifnumBitsis 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.
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length
Returns the total length of the stream, if known. Otherwise,-1is returned.- Returns:
- a
longcontaining the length of the stream, if known, or else-1. - Throws:
IOException- if an I/O error occurs.
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skipBytes
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.- Specified by:
skipBytesin interfaceDataInput- Parameters:
n- anintcontaining the number of bytes to be skipped.- Returns:
- an
intrepresenting the number of bytes skipped. - Throws:
IOException- if an I/O error occurs.
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skipBytes
Moves the stream position forward by a given number of bytes. This method is identical toskipBytes(int)except that it allows for a larger skip distance.- Parameters:
n- alongcontaining the number of bytes to be skipped.- Returns:
- a
longrepresenting the number of bytes skipped. - Throws:
IOException- if an I/O error occurs.
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seek
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
IndexOutOfBoundsExceptionwill be thrown ifposis smaller than the flushed position (as returned bygetflushedPosition).It is legal to seek past the end of the file; a
java.io.EOFExceptionwill be thrown only if a read is performed.- Parameters:
pos- alongcontaining the desired file pointer position.- Throws:
IndexOutOfBoundsException- ifposis smaller than the flushed position.IOException- if any other I/O error occurs.
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mark
void mark()Marks a position in the stream to be returned to by a subsequent call toreset. Unlike a standardInputStream, allImageInputStreams support marking. Additionally, calls tomarkandresetmay be nested arbitrarily.Unlike the
markmethods declared by theReaderandInputStreaminterfaces, noreadLimitparameter is used. An arbitrary amount of data may be read following the call tomark.The bit position used by the
readBitsmethod is saved and restored by each pair of calls tomarkandreset.Note that it is valid for an
ImageReaderto callflushBeforeas part of a read operation. Therefore, if an application callsmarkprior to passing that stream to anImageReader, the application should not assume that the marked position will remain valid after the read operation has completed. -
reset
Returns the stream pointer to its previous position, including the bit offset, at the time of the most recent unmatched call tomark.Calls to
resetwithout a corresponding call tomarkhave no effect.An
IOExceptionwill be thrown if the previous marked position lies in the discarded portion of the stream.- Throws:
IOException- if an I/O error occurs.
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flushBefore
Discards the initial portion of the stream prior to the indicated position. Attempting to seek to an offset within the flushed portion of the stream will result in anIndexOutOfBoundsException.Calling
flushBeforemay 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.- Parameters:
pos- alongcontaining the length of the stream prefix that may be flushed.- Throws:
IndexOutOfBoundsException- ifposlies in the flushed portion of the stream or past the current stream position.IOException- if an I/O error occurs.
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flush
Discards the initial position of the stream prior to the current stream position. Equivalent toflushBefore(getStreamPosition()).- Throws:
IOException- if an I/O error occurs.
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getFlushedPosition
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 toflushBefore.- Returns:
- the earliest legal position for seeking, as a
long.
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isCached
boolean isCached()Returnstrueif thisImageInputStreamcaches 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.- Returns:
trueif thisImageInputStreamcaches data.- See Also:
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isCachedMemory
boolean isCachedMemory()Returnstrueif thisImageInputStreamcaches 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.- Returns:
trueif thisImageInputStreamcaches data in main memory.- See Also:
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isCachedFile
boolean isCachedFile()Returnstrueif thisImageInputStreamcaches 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.- Returns:
trueif thisImageInputStreamcaches data in a temporary file.- See Also:
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close
Closes the stream. Attempts to access a stream that has been closed may result inIOExceptions 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:
closein interfaceAutoCloseable- Specified by:
closein interfaceCloseable- Throws:
IOException- if an I/O error occurs.
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